Article

Roosting of Yellow-naped Parrots in Costa Rica: Estimating the size and recruitment of threatened populations

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Abstract

Many parrot populations are threatened with extinction due to habitat loss and collection for the pet trade. The loss of nest trees and chick poaching can drastically reduce reproductive success. However, due to the long life span of many parrots, populations are unlikely to become extinct rapidly even with complete reproductive failure. For parrots that travel in family groups, rapid estimates of reproductive success can be obtained by recording group sizes in areas where they congregate. We used roost counts over an 18-month period to estimate the size and productivity of a population of Yellow-naped Parrots (Amazona auropalliata auropalliata) in Costa Rica. Up to 300 birds were observed flying to roost on offshore islands near Curú National Wildlife Refuge. Roost counts were lowest during the breeding period (December–March), increased after fledging (April–July), and peaked during the late wet season (September–October). Increased food availability on the islands during the breeding season allowed the parrots to become seasonal island residents, and lowered roost counts during that period. We calculated reproductive parameters by assuming that groups of >2 birds were adults traveling with young. The percentage of young in the population was 12.5% and did not differ between years. Studies of group size in birds that form stable family groups, such as psittacines in the genera Amazona and Ara, are an inexpensive way to obtain estimates of the reproductive output of some parrot populations and determine if further study or intensive management are warranted.

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... The family flocks could usually be distinguished, as the birds flew in close proximity, up to five meters from one another, and the young often interact (e.g., changing their position during flight and playing) and follow the adults. Because these family flocks are composed of the parental pair plus their one to four fledglings (e.g., [17,36]), we discounted the parental pair in each counted family flock [18] when analyzing the data related to the number of fledglings. The counts were conducted when the sky was clear enough to distinguish the birds in flight, and we avoided adverse climatic conditions, such as rains and strong winds. ...
... Pooling the roosts together, we would expect a median increase of approximately 206 fledglings (4.5%) in a given year. These estimates are at the same magnitude as those found in other studies that focus on nonprotected populations of parrots: 2.3-4.6% for Red-tailed Parrots (Amazona brasiliensis) [28], 12.5% for Yellow-naped Parrots (Amazona auropalliata) [18] and 14% for Red-fronted Macaws (Ara rubrogenys) [53]. However, most of the authors (e.g., [28,29]) used the counts of young in the family groups to estimate recruitment a few months after the fledging period. ...
... The difference of 20-25% between the estimates of recruitment based on the proportion of singletons and based on the proportion of fledglings could be accounted for by the mortality of the fledged young over time between the period of fledging (Nov-Dec) and period of the maximum number of birds in roosts (Jun-Jul). Some authors [18] recognized that such post-fledging mortality in parrots might be considerable (but see also [54]), and it could reach up to 35% for Great Green Macaws (Ara ambigua) during the first year after fledging. Therefore, the use of the singleton counts to access the fledging rate and family flock counts to access the post-fledging recruitment can provide insights into post-fledging mortality rates. ...
Article
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Psittacidae species are among the most threatened birds in the world. Approximately one-half of the 390 parrot species are experiencing population declines. The Blue-fronted Amazon (Amazona aestiva) is the most traded parrot worldwide and suffers from poaching and habitat loss. Many species of parrots, including the Blue-fronted Amazon, form communal roosts where they spend the night. Under certain circumstances, roost surveys can be a rapid and cost-effective way to obtain information about the demography of parrots or the consequences of threats. We surveyed an area of 2,700 km² in a large wetland in mid-western of Brazil and located five Blue-fronted Amazon roosts. We conducted monthly counts of the birds arriving at these roosts for 28–61 months and stratified the counts into flock sizes. We used this information to estimate the number of parrots using these roosts to determine whether the roosts follow seasonal patterns and whether they have different flock-size structures and different dynamics throughout the year, as well as to determine the trends of the roosting parrots, which are stratified by flock size. The roosts were different, as they followed different seasonal patterns and had different flock-size structures, which could be interpreted in relation to the parrot breeding cycle. The trends of singletons, which index the number of reproductive couples each year, and the number of pairs parrots increased or fluctuated around a baseline, but the number of fledged young in the year declined throughout the study. This is of concern, as it indicates problems in population recruitment, which could have been unnoticed by the management authorities, as the total numbers were not decreasing. Although every monitored roost had birds of each age or reproductive condition strata, the fact that the roosts were different could be important in terms of management, as it will be more effective for the conservation of the Blue-fronted Amazon to protect a carefully chosen set of complementary roosts.
... Wright, C. Dahlin & M. Lezama unpubl. data), so these two time-periods represented the best times to estimate the number of parrots arriving at or departing from night roosts (Cougill andMarsden 2004, Matuzak andBrightsmith 2007). Cougill and Marsden (2004) conducted morning and evening roost counts at a single roost of the Redtailed Amazon Amazona brasilensis in Brazil and observed no systematic bias in the number of birds observed in the morning versus the evening; for that reason we include data from both types of counts in our study. ...
... The majority of roosts observed in 2016 had fewer than 50 birds, and a direct comparison of 12 roosts counted in 2004 and 2016 showed a 54% decline in mean roost size over the 11-year period. Matuzak and Brightsmith (2007) estimated that during their study the Curú roost consisted of around 300 birds; in our survey 12 years later we counted only 17 birds, representing a 95% decline in numbers at this roost. The rapid decline at many roosts, low overall population numbers and the small average size of most local populations are all cause for significant concern about the long-term viability of this species at the southern portion of its Central American range. ...
... This proportion is roughly similar to those seen in other studies using similar methodology. A study conducted at the Curú site in Costa Rica in the post-breeding seasons found that 17-18% of groups flying to or from the roost consisted of pairs with young (Matuzak and Brightsmith 2007), while counts of Red-tailed Amazons at a single roost over an entire year throughout found 18% of groups flying to roosts and 24% of groups flying from roosts consisted of three or more individuals (Cougill and Marsden 2004). It is important to evaluate, however, the critical assumption that groups of three or more birds consist of mated pairs and their recently fledged young. ...
Article
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Accurate assessments of population sizes and trends are fundamental for effective species conservation, particularly for social and long-lived species in which low reproductive rates, aging demographic structure and Allee effects could interact to drive rapid population declines. In the parrots (Order Psittaciformes) these life history characteristics have combined with habitat loss and capture for the pet trade to lead to widespread endangerment, with over 40% of species classified under some level of threat. Here we report the results of a population survey of one such species, the Yellow-naped Amazon, Amazona auropalliata , that is classified as ‘Endangered’ on the IUCN Red List. We conducted a comprehensive survey in June and July of 2016 of 44 night roosts of the populations in contiguous Pacific lowlands of northern Costa Rica and southern Nicaragua and compared numbers in Costa Rica to those found in a similar survey conducted in June 2005. In 2016 we counted 990 birds across 25 sites surveyed in Costa Rica and 692 birds across 19 sites surveyed in Nicaragua for a total population estimate of only 1,682 birds. Comparisons of 13 sites surveyed in both 2005 and 2016 in Costa Rica showed a strong and statistically significant decline in population numbers over the 11-year period. Assessment of group sizes approaching or leaving roosts indicated that less than 25% of groups consisted of three or more birds; there was a significantly higher proportion of these putative family groups observed in Nicaragua than Costa Rica. Taken together, these results are cause for substantial concern for the health of this species in a region that has previously been considered its stronghold, and suggest that stronger conservation action should be undertaken to protect remaining populations from capture for the pet trade and loss of key habitat.
... Sumado a esto, estudios recientes han demostrado que los Psitácidos presentan bajas tasas reproductivas, y requerimientos específicos de hábitat y geográficos (Monterrubio-Rico et al. 2009, Ortega-Rodríguez and Monterrubio-Rico 2008, Renton 2001, Renton and Salinas-Melgoza 1999, lo cual aumenta la vulnerabilidad de las especies silvestres ante modificaciones de su hábitat. ...
... Aratinga canicularis la especie más abundante en todos los tipos de vegetación estudiados, hábitat en ese periodo particular (Matuzak andBrightsmith 2007, Snyder et al. 2000). ...
... En el caso de Aratinga canicularis es difícil establecer una relación entre abundancia y tipo de vegetación que la favorezca debido a la baja cantidad de individuos registrados en cada sitio, aunque su mayor abundancia se observó en Palos Marías, un sitio con importante presencia de selva mediana e importante presencia de superficie agropecuaria.En la región de la costa de Jalisco las mayores abundancias de Amazona finschi y Aratinga canicularis se encuentran relacionadas a la presencia de bosque tropical caducifolio y subcaducifolio conservados, mientras que sus menores abundancias se registraron en los sitios perturbados (Morales-Pérez 2005). de NDVI en los sitios de estudio En general, en México existen relativamente pocos estudios sobre monitoreo poblacional de Psitácidos silvestres donde se contraste la abundancia en respuesta a diferentes niveles de alteración del hábitat(Monterrubio-Rico et al. 2009, Téllez-García 2008, Renton and Íñigo-Elías 2003, Huerta-Heredia 2007. Combinando la información del Inventario Forestal Nacional y el Índice de Vegetación de Diferencia Normalizada (NDVI, por sus siglas en inglés). ...
Thesis
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Habitat fragmentation and its complete loss are the most important threats to Psittacids in México. The present study assessed and related the impact that deforestation and habitat loss has had on the local and regional abundances of two parrot species at the coastal line of the state of Michoacán: the Orange-fronted Conure (Aratinga canicularis) and the Lilac-crowned Parrot (Amazona finschi). Data was collected during two annual cycles, in eight consecutive periods, for five sites located along the Michoacán Coastal Line. Descriptive and normality analysis were conducted as to evaluate the differences in abundance for both parrot species cross-sites and cross-seasons. Furthermore, a Vegetation Index Analysis was conducted in order to determine the influence that vegetal coverage has over the population density of both species. It was determined that Amazona finschi is the most abundant species in the region, with important variations at local and seasonal levels. On the other hand, Aratinga canicularis was completely absent from one of the study sites and during the second year exhibited an important decline on its abundances at other three study sites. The results demonstrate that the availability of well preserved habitat, mainly tropical forest, is fundamental for the conservation of both parrot species.
... Macaws observed were a group of 9-12 birds that had been released 4 years prior to the onset of our study (Brightsmith et al. 2005). Yellow-naped Parrot is a threatened species (CITES 2002) and the area contains one of the largest known roosting populations of the species in Costa Rica with a minimum of 300 individuals (Matuzak and Brightsmith 2007). ...
... The small-bodied parakeets and Amazona parrots showed the most similarity in overall psittacine diets, suggesting that congeneric and similar-sized species forage on a large subset of the same plant species. The greater similarity in psittacine diets in the wet season as opposed to the dry season could be related to fewer species of trees producing parrot food in the wet season (Matuzak and Brightsmith 2007) making it more likely that psittacines would forage on the same plant species. Smaller parrot species such as those in Brotogeris and Aratinga often increase in abundance in modified landscapes, as larger parrot species decline (Karubian et al. 2005). ...
... Diet breadth among parrots usually increases with increasing food abundance and diversity of available food items (Wermundsen 1997, Renton 2001. This pattern held for only one species in our study, White-fronted Parrot, which had a 260% increase in diet breadth when food availability peaked in the dry season (Matuzak and Brightsmith 2007). The increase in diet breadth of Orange-chinned Parakeets during the wet season could also be related to food abundance, as fruit pulp (the species preferred food part) abundance peaks at this time of year (GDM, unpubl. ...
Article
We studied the diet and foraging ecology of a community of six psittacines in western Costa Rica. All had a varied diet with clear seasonal changes in preferred food items, mostly due to changes in plant phenology. There was a significant relationship between parrot mass and food types: larger-bodied parrots con- sumed more seeds and smaller-bodied parakeets consumed more fruit pulp. Leaves, bark, and lichen were also consumed by most psittacines. Most parrots consumed more plant species in the dry season when food avail- ability was at its peak. Levins' niche breath showed varying levels of diet specialization among species and, for some species, variation among seasons. There was less similarity in seasonal psittacine diets when compared to overall diets. Scarlet Macaws (Ara macao) under study were captive raised and released which may have contributed to their narrow diet breadth as they may have lacked the knowledge or experience to exploit addi- tional food sources. Non-native and cultivated species comprised 76% of the diet of Scarlet Macaws, and averaged 28% for all other species. This suggests that foraging parrots may have increased conflicts with humans as landscapes become increasingly modified. Forest restoration strategies should augment the abundance of food species consumed when overall food supply is at its annual low. Received 20 February 2007. Accepted 4 September 2007.
... They are registered in high number early in the morning and late afternoon (Pizo et al. 1997), and counts in the middle of the day should be avoided because activity of parrots decreases abruptly at this time (Marsden 1999). Roost counts may permit targeted assessments of parrot populations in small areas and on islands where parrots roost communally (Snyder et al. 1987, Matuzak andBrightsmith 2007). ...
... Counting Method.-The method used in this study of counting parrots from a fixed site as they arrived at or left the roost is similar to that used by other parrot researchers who have studied other parrot species (Rocha et al. 1988, Guedes 1993, Casagrande and Beissinger 1997, Mabb 1997, Martinez and Prestes 2002, Harms and Eberhard 2003, Cougill and Marsden 2004, Berg and Angel 2006, Costa 2006, Matuzak and Brightsmith 2007. Some parrots could have arrived at or left the island by routes not countable from the survey boat. ...
... It is common that numbers of parrots at roosting sites diminish during the period when pairs need to find nest sites, lay, and incubate eggs (Cannon 1984, Chapman et al. 1989, Carrillo et al. 2002. These findings are similar to those reported for other species of parrots (Mabb 1997, Olmos 1997, Berg and Angel 2006, Costa 2006, Matuzak and Brightsmith 2007; however, the period of low attendance at the roost is particularly long at our study site. Orange-winged Amazons have asynchronous reproduction that may account for the long time between the decrease of the roost population and the return of pairs with young. ...
Article
Full-text available
We recorded fluctuations in a population of Orange-winged Amazon (Amazona amazonica) during 1 year at a roosting site on an island near Belém, Pará, Brazil. Parrots were counted from a boat by a minimum of three teams of two observers, each team oriented in different directions. Orange-winged Amazons were observed flying alone (14.2%), in pairs (75.7%), and small numbers in family groups (pairs with young) of three (8.7%), four (1.2%), or five (0.3%) individuals. The larger number of groups of three compared with groups of four and five individuals reflects the low survival rate of nestlings with generally only one surviving offspring per brood. The total number of parrots increased from April (3,899) to July (8,539), and began to decrease in August (5,351). This decrease was presumably due to onset of the breeding season, when paired individuals leave the roost in search of a nest, where they breed, nest, and rear young until the nestlings can fly.
... Despite the importance of understanding population size and demography, limited information is available for parrot populations in the wild (Valle et al. 2017;Dénes et al. 2018). Monitoring parrot populations can be challenging because of their tendency to inhabit densely vegetated habitats, use vertical space, and make changes in habitat use and movement patterns linked to spatial and temporal changes in resource availability (Casagrande and Beissinger 1997;Matuzak and Brightsmith 2007;Dénes et al. 2018;Zulian et al. 2020). However, when widely dispersed local populations congregate in large numbers, their gatherings present an opportunity to estimate population abundance, and conducting these counts during similar times across years allows for estimating long-term trends of population metrics (Dénes et al. 2018;Zulian et al. 2020). ...
... In parrots, the numbers of birds using roost sites typically varies because of seasonal changes in behaviour. One explanation for the gradually diminishing numbers as the breeding season advances is breeding birds roosting inside their nests, followed by an increase toward the end of the season after young fledge (Matuzak and Brightsmith 2007;Dénes et al. 2018). Similarly, Cape Parrot roost counts were typically highest during January-June, after the end of the breeding season (Carstens et al. 2022a) when juveniles fledged and would remain in their natal area for a few months. ...
... de las especies (Berg & Angel, 2006;Cougill & Stuart, 2004;Fernandes-Seixas & Mouräo, 2018;Matuzak & Brightsmith, 2007). ...
... Si bien es cierto que estos factores físicos influyen en las concentraciones de los loros, también cambian el seguimiento de las rutas de vuelo hacia los dormideros. Otro factor observado es el periodo reproductivo, cuando las parejas no siempre llegan a los dormideros, sino que permanecen en la zona de anidación, reduciéndose los avistamientos, y cuando finaliza, el número de observaciones aumenta, esto se aprecia en los resultados expuestos en la Figura 3. Este comportamiento lo registró también Matuzak & Brightsmith, (2007) para la misma especie en Costa Rica. ...
Article
Full-text available
La lora nuca amarilla, Amazona auropalliata ha logrado establecer poblaciones silvestres adaptándose a entornos urbanos. En esta nota se presentan los resultados del registro de individuos en sus rutas a los dormitorios comunales. Se hicieron observaciones entre abril 2020 a marzo 2021, desde cuatro puntos de avistamiento en el noreste de la ciudad de San Salvador, con un promedio de 35.76 min, para un total de 170 conteos y 100.06 horas de observación. Los resultados arrojaron un promedio de 2.42 individuos en 125 observaciones exitosas, con una ocurrencia entre las 17:26 a las 18:29 horas, existiendo más registros en el periodo de abril a julio, cuando la especie no se está reproduciendo, hay más juveniles volando y las condiciones climáticas son favorables para la observación. El análisis de correlación de Spearman entre la puesta del sol y la hora de paso de los loros (R2 = 0.26) evidencia que los movimientos vespertinos no están influenciados por el fenómeno.
... comm.). Evening roost counts may provide the most useful data for estimating local populations of Yellow-naped Parrots, with observations best conducted up to 90 minutes before nightfall (Matuzak & Brightsmith 2007). ...
... This now scarce species can be difficult to encounter on a trip to the region; some of the more reliable areas in the past decade are Ometepe Island in Lake Nicaragua (pers. obs.), Guanaja Island and Río Platano National Park, Honduras (Forshaw 2006), and many locations in northwestern Costa Rica, including Curú National Wildlife Refuge (Matuzak & Brightsmith 2007, Matuzak et al. 2008) as well as the area around Cañas Dulces and Liberia (Salinas-Melgoza et al. 2013). However, birders are encouraged to look out for this species away from well-known locations. ...
... Roost surveys have been used to estimate global and local population sizes in many parrots species (e.g. Gnam and Burchsted 1991, Martuscelli 1995, Matuzak and Brightsmith 2007, Dénes et al. 2018) and provide a tool for long-term population monitoring (e.g. Wermundsen 1998, Wright et al. 2019. ...
... Although we know little about this species' reproductive behaviour, adults appear to explore cavities in October/November and produce one or two chicks that fledge between mid-February and late-March (Kunz 1996, Berg andAngel 2006). As with several other Amazona species, with the exception of breeding birds, or at least females during the incubation and early chick stages, it returns to communal roost sites every evening e.g. A. brasiliensis (Cougill and Marsden 2004), A. auropalliata auropalliata (Matuzak and Brightsmith 2007), and A. amazonica (de Moura et al. 2012). For A. lilacina, these roost sites mainly occur on mangrove islands where birds join together every night (Berg and Angel 2006). ...
Article
Amazona lilacina is a threatened species endemic to Ecuador, existing across a patchwork of mangroves, lowland coastal forests, agricultural and community owned land. The species was described in 2014 and listed as ‘Endangered’ on the IUCN Red List, however, full assessment of the population was lacking. Using a combination of field observations, roost surveys and community questionnaires, conducted over the last 20 years, we provide up-to-date information on the species’ Extent of Occurrence, estimate its global population size, and evaluate its level of threat. Our results suggest the species occurs across an area of 19,890 km ² in three distinct geographically isolated subpopulations. Roost surveys across the range estimate the minimum remaining population at 741–1,090 individuals and we present evidence to suggest a 60% decline over the past 19 years in one part of the species’ range. We conducted community questionnaires with 427 people from 52 communities. The presence of pet parrots was reported in 37 communities, including 17 communities which reported pet A. lilacina. From this we predict that over half of all communities within our study area keep parrots as pets and at least 96 communities keep A. lilacina. Our findings justify an IUCN Red Listing of at least ‘Endangered’ for this species and highlight the need for conservation support. In order to assess population health in more detail, further research is required to assess genetic diversity and roost dynamics, and to identify areas that may be important for feeding and nesting throughout the range. As many of these areas are likely to overlap with community owned land, we suggest that future conservation actions should revolve around, and be led by, these communities.
... The real benefit of undertaking roost count surveys is that they allow demographic, in addition to population, data to be collected. This allows the estimation of both recruitment and fledging rates, and an assessment of the size of the effective breeding population at the roost (Matuzak and Brightsmith 2007). Overall, roost count surveys can potentially provide useful information on changes in the roosting populations of threatened Amazona taxa (Pitter and Christiansen 1995). ...
... The totals of each observer will then be compiled. Similar to the method used by Matuzak and Brightsmith (2007), to estimate the proportion of breeders in the population and potential recruitment of young, it is assumed that all groups of 3-5 parrots consisted of pairs with one, two, and three young, respectively. Because family groups in other parrot species in the genus Amazona break up about 5 months after fledging, the period from 2 -5 months after nesting appears to be the best time to determine the size of family groups and the recruitment of recentlyfledged young. ...
Technical Report
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A collaborative effort was undertaken in 2016 by members of the Yellow‐headed Parrot Working Group (and supporters) to assess the status of the globally endangered Yellow‐headed Parrot (Amazona oratrix) across Belize. This included transect surveys, roost searches and counts, and nest searches and monitoring across the pine savannahs. Transect surveys revealed a higher density in protected areas, both dense and open, than found in unprotected areas. This is likely related to higher quality habitat present as logging is rampant in the pine savannahs across and wildfire is also problematic. However, unprotected dense savannahs may be an important habitat type as well. Roost searches and counts were challenging and largely unsuccessful for assisting with the assessment of the population. They ranged from permanent and seasonal roosts in southern Belize to dynamic roosts in the north where repeated counts at the same sites were not possible. There were 89 known active nests, of which 76 were monitored; primarily in three protected areas. Twenty‐nine were successful producing 58 fledglings. 13 at‐risk chicks were extracted from 7 nests and later soft‐released. Poaching was the largest known reason for nest failure.
... We chose this model for our telemetry data because it relaxes the assumption that the exact failure date be known as in Kaplan-Meier approaches (Pollock et al. 1989).We modeled survival for a 90-day period post-fledging. For Amazona parrots, this period corresponds to the immediate post-fledging and dependence phases, during which fledglings acquire survival skills and integrate into wild flocks (Snyder et al. 1987, Lindsey et al. 1991, Matuzak and Brightsmith 2007, Salinas-Melgoza and Renton 2005.We did not attempt to model survival beyond the 90-day period due to reduced sample sizes and attendant decreased precision in parameter estimates resulting from the combined effect of cumulative deaths and censored observations. On three occasions, a bird was known to have survived the 90day period, but was censored before end of the period. ...
... The Red-tailed hawk (hereafter, RTH) is the primary predator of the PRP (Snyder et al. 1987, Lindsey et al. 1994, White et al. 2005b, and beginning in 2003 a program was initiated to reduce extremely high RTH population densities (see Snyder et al. 1987, Boal et al. 2003, Nimitz 2005, both within and adjacent to the parrot nesting area. We hypothesized that parrot survival would be enhanced in years with predator reduction (see Engemann et al. 2005, Livezey 2010, Pieron and Rohwer 2010.We modeled a daily fledgling age effect because we believed that as fledglings aged survival would increase, similar to patterns found in other psittacines (e.g., Myers and Vaughan 2003, Stahala 2005, Matuzak and Brightsmith 2007, Salinas-Melgoza and Renton 2007. Beissinger et al. (2008) reported that extremes in rainfall resulted in decreased adult survival of PRPs in the Luquillo Mountains. ...
Chapter
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The factors which govern species’ distribution and abundance are myriad, and together constitute the ecological niche of a given species. Because abiotic factors are arguably the most profound of the factors influencing niche boundaries and thus, species distributions, substantial changes in either climatic or habitat-related parameters can be expected to produce interrelated and profound niche shifts. Habitat loss and degradation can also effectively induce a de facto climate change by forcing populations to relocate to environmentally suboptimal habitats. Populations experiencing niche shifts due to range restrictions and geographic isolation become subject to a suite of factors that may act synergistically to amplify deleterious ecological effects of habitat loss. These factors tend to exert a greater influence on populations of rare or endemic species with inherently restricted ranges. The Puerto Rican parrot (Amazona vittata) is an example of a tropical, insular, endemic and critically-endangered species that has suffered from extensive habitat loss and degradation over the past century, resulting in a single relict wild population restricted for more than 70 years to the montane rainforest of the Luquillo Mountains in northeastern Puerto Rico. In this chapter, we examine the current ecological situation of this geographically and demographically isolated parrot population by reviewing the history of landscape-level changes in and around the Luquillo Mountains, and concurrent biotic and abiotic limiting factors in relation to both historical population trajectory and current prognosis for species recovery. We used a decade (2000-2009) of empirical data on parrot fledgling survival together with long-term climatological data to model effects of local climate on fledgling survival and gain insights into its influence on population growth. We also modeled hypothetical survival of parrot fledglings in the lowlands surrounding the Luquillo Mountains, areas currently deforested but previously occupied by parrots, to illustrate both quantitative and qualitative losses of reproductive habitat for the species. We illustrate and systematically discuss how progressive and sustained changes in landscape composition and associated limiting factors have effectively shifted and restricted the ecological niche of this species, and how this complex suite of ecological processes affects the Puerto Rican parrot in the Luquillo Mountains. Our niche restriction hypothesis is supported by the demographic response of Puerto Rican parrots recently (2006-2009) reintroduced in the lower elevation karst forest of northwestern Puerto Rico. Based on our findings, we present conservation strategies aimed at promoting the recovery of the species both in the Luquillo Mountains and elsewhere in Puerto Rico. Finally, we address the relevance of our findings to conservation of other endangered species, particularly those threatened by both habitat loss and climate change.
... Many parrot species roost communally and more than a third are threatened from habitat loss or poaching for the pet trade (IUCN, 2022). For the critically endangered yellow-naped parrot (Amazona auropalliata) and endangered vinaceous-breasted parrot (Amazona vinacea), roost counts provide a useful means of monitoring their populations (Matuzak & Brightsmith, 2007;Zulian et al., 2020). ...
Article
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Communal bird roosts serve as information centres and a means of thermoregulation for many species. While some communally roosting species are major pests and cause dis‐amenities, others are of conservation concern. Estimating the population of roosting birds can provide a useful proxy of population size and possibly a more reliable estimate than other sampling techniques. However, estimating these populations is challenging as some roosts are large and often occluded in foliage. Previous acoustic methods such as paired sampling, microphone arrays and use of call rate have been used to estimate bird abundances; however, these are less suited for estimating large roost populations where hundreds of individuals are calling in unison. To address this challenge, we explored using machine learning techniques to estimate a roost population of the Javan myna, Acridotheres javanicus, an invasive species in Singapore. While one may expect to use sound intensity to estimate roost sizes, it is affected by various factors such as distance to the recorder, local propagation conditions (e.g. buildings and trees), weather conditions, and noise from other sources. Here, we used a deep neural network to extract higher order statistics from the sound recordings and use those to help estimate roost sizes. Additionally, we validated our method using automated visual analysis with a dual‐camera setup and manual bird counts. Our estimated bird counts over time using our acoustic model matched the automated visual estimates and manual bird counts at a selected Javan myna roost, thus validating our approach. Our acoustic model estimated close to 400 individual mynas roosting in a single tree. Analyses of additional recordings of Javan myna roosts conducted on two separate occasions and at a different roost location using our acoustic model showed that our roost estimates over time also matched our automated visual estimates well. Practical implication: Our novel approach of estimating communal roost sizes can be achieved robustly using a simple portable acoustic recording system. Our method has multiple applications such as testing the efficacy of avian roost population control measures (e.g. roost tree pruning) and monitoring the populations of threatened bird species that roost communally.
... The behaviour of many species to habitually use communal overnight roost sites provides an opportunity to gain insights into parrot abundance (Casagrande and Beissinger 1997;Dénes et al. 2017). Roost counts have been used to estimate the abundance of parrot species around the world (Gnam and Burchsted 1991;Dändliker 1992;Downs 2005;Matuzak and Brightsmith 2007). For Grey Parrots, an endangered but widespread species in tropical Africa, roost counts have been used as a basis for population estimates at national [e.g., Nigeria (McGowan 2001), Ghana (Dändliker 1992), Cameroon (Fotso 1998a), Democratic Republic of Congo (Fotso 1998b)] and global levels (e.g., BirdLife International 2023). ...
Article
Estimating abundance and trends in populations is important for efforts to conserve biodiversity and understand species’ behaviour and ecology. For species that predictably aggregate in overnight communal roost sites, like many parrot species, roost counts are often used as a proxy for local abundance. However, accurately counting the number of birds present at overnight roosts can be challenging due to low light levels and the behaviour of parrots as they arrive which can lead to double counting and highly variable estimates between observers. Here, we report on a method for counting parrots and other birds at overnight communal roosts, using “night-vision” cameras to count endangered Grey Parrots (Psittacus erithacus) at a site in Nigeria. We compared the level of dispersion (standard deviation) in parrot counts made using “traditional” methods (using optical binoculars to count parrots at dusk as they arrived at a roost site) with counts made using night-vision camera and found that the latter achieved greater consistency between multiple independent observers. Although the use of a night vision camera will not be suitable in all situations, particularly those involving trees with dense foliage, we advocate for its use when making roost counts wherever feasible to achieve greater precision and repeatability of results and make recommendations for implementing this method.
... Larger group sizes are known to provide a wide variety of advantages to many species, including reduced predation rates, increased opportunities for finding mates, improved foraging efficiency, etc. In parrots, most species spend nearly all their time in social groups ranging from pairs to flocks of 100s individuals [48][49][50], and flying in cohesive flocks is a key anti-predator response [2,6]. While parrots are naturally drawn to conspecifics, many captive-raised parrots fly off and spend much time alone when released into the wild [6,8,13,23]. ...
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As habitat loss and other threats accelerate, ecological restoration and reintroduction science are becoming progressively more important. The psittacines are among the most endangered bird groups and are prime candidates for restoration through reintroduction. Unfortunately, post-release survival of captive-raised animals is often quite low because, in part, of high predation rates, low site fidelity, poor flight ability, and low flock cohesion. Current best practices in parrot release hold the birds in captivity for a year or more and include distinct methods to address each of these challenges. Here, we conduct a small-scale, proof-of-concept study using free flight methods and human-socialized trained adult birds to hand raise and release a group of six fledgling Blue-and-yellow Macaws in their historical range in southeastern Brazil. All six released birds showed strong flock cohesion and fidelity to the release site, avoided predation, and survived without supplemental feeding for over one year. One bird was captured by local people but was recovered and rereleased and it has reintegrated into the group and is still alive and doing well. The human-socialized trained adult birds modeled both desirable behaviors (flocking, foraging, reacting to predators) and undesirable behaviors and they were returned to captivity before the conclusion of this study. Our study suggests that free flight training has great potential to help captive-raised young attain a broad array of vital skills needed for survival post-release.
... We recorded contact calls from yellow-naped amazons during June and July of 2016, 2018, and 2019; both months fall just after the species' breeding season (Matuzak and Brightsmith, 2007;Dahlin et al., 2018). Sites were chosen based on previous survey history, local anecdotes, information from local organizations working with yellow-naped amazons, and eBird reports. ...
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Introduction Vocal dialects are a taxonomically widespread phenomenon which are typically only studied in a portion of a species’ range. Thus, it is difficult to infer whether a geographic pattern of vocal dialects observed in one part of a species’ range are typical across the range or whether local conditions influence their presence or absence. We examined the yellow-naped amazon, Amazona auropalliata , a parrot species with remarkable vocal learning capabilities. Although this species’ native range spans across Mesoamerica, only Costa Rican populations have been evaluated long-term. Previous studies have shown that these populations have geographically and temporally stable vocal dialect patterns. Without data on populations outside of Costa Rica, it is impossible to know whether vocal dialects are present in northern range populations, and whether they show similar geographic structure to southern range populations. Introduction We recorded yellow-naped amazon contact calls at 47 different sites across the species’ range between 2016 and 2019 and evaluated them for the presence of dialects. We visually classified 14 contact call types based on spectrographic similarity and used spectrographic cross-correlation, principal component analysis, and Mantel-based spatial autocorrelations to assess acoustic similarity; we also evaluated the robustness of our findings using simulated data. Results and Discussion The results from our study show that the vocal patterns previously seen in Costa Rica are also present in northern populations, supporting our hypothesis that this species has vocal dialects throughout its Mesoamerican range. Call types were regionally specific (e.g., vocal dialects occurred) across the range, and no call types were repeated across multiple regions. We did, however, observe distinctive structural characteristics that are found in multiple call types, suggesting that different call types stem from a common origin. Alternatively, similarity in the acoustic features of call types may also be a result of physiological and anatomical features that are common to all members of the species. Vocal dialects in this species are likely maintained through a tendency toward philopatry and matching call types to enhance social identification.
... For instance, counts of roosting Yellow-naped Parrots (Amazona auropalliata) in Costa Rica documented a population of ~300 individuals, with no apparent decline between the 2-year study period. However, only 12.5% of the population was composed by juvenile birds (Matuzak and Brightsmith 2007), suggesting that, although the abundance of observed birds was high, this population was already experiencing low rates of fecundity and recruitment. Roost counts conducted 12 years later documented a 95% decline in number of individuals at this site (Wright et al. 2019), highlighting the serious threat faced by populations with limited recruitment (Bennett and Owens 1997). ...
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The endangered Yellow-headed Parrot (Amazona oratrix) has experienced a considerable reduction in abundance and distribution. Identifying natural and anthropogenic causes of nest failure is a critical step towards developing conservation actions that increase nest survival. In this study, we examined daily nest survival in relation to temporal, habitat, and anthropogenic factors, as well as nest site properties. We monitored nests (n = 124) across 6 study sites in Belize during 2017 and 2018 and independently modeled the effects of predation, abandonment and poaching on daily nest survival rates. Overall, the estimated cumulative nest survival probability was 0.18 (95% CI: 0.12–0.25). Predation was the main cause of nest failure, followed by abandonment, and poaching. Our results showed that nest predation and abandonment usually occurred early in the nesting cycle. Day within the nesting season negatively influenced daily survival for abandoned nests and had a quadratic effect on survival for poached nests. Poaching events occurred at a specific date range later in the season, with nests farther from the nearest human settlement having higher daily survival. Findings from this study highlight the additive mortality effect that nest poaching is having on Yellow-headed Parrot populations in Belize and show that managers can anticipate the timing and location of nests most vulnerable to poaching.
... Apart from these potential indirect effects of exploitation, we also found evidence of recent cockatoo trapping (climbing set-ups, nooses and bunches of flight feathers at roosts and nests; Fig. 2) in at least twelve cases, and investigations confirmed that trapping of adults and young, although at low levels, appears to have been increasing since 2017. We saw fewer fledglings accompanying their parents to communal roosts than would be expected after a productive breeding season (Matuzak and Brightsmith, 2007;Widmann and Lacerna-Widmann, 2008). If other typical limiting factors of nest productivity-predation, infertile eggs, embryo death, malnutrition, parasites (Clout and Merton, 1998;Arendt, 2000;White et al., 2015;Stojanovic et al., 2017;Vigo-Trauco et al., 2021)-were frequent, we would expect to have found some evidence for them. ...
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Knowledge of breeding success and its limiting factors is crucial in assessing species’ conservation needs. As cavity-nesters, parrots are particularly influenced by the availability of suitable cavities and low breeding output, whether due to natural processes or trapping. On the island of Sumba, Indonesia, the Critically Endangered Citron-crested Cockatoo (Cacatua citrinocristata) has the added problem of co-existing with an unusually rich hole-nesting bird community in a forested environment much constrained by habitat loss. We monitored 95 nesting cavities of cockatoos and their competitors and potential nest-predators, over one to four breeding seasons, using a combination of camera-traps, direct checks on nest contents, and observations from the ground. Competition for suitable cavities was intense among three large parrot species, two owls and a hornbill. Visitation rates by potential competitors were higher at unoccupied cavities than at those containing active nests, reflecting the guarding behaviour of the occupants. The Endangered Sumba Hornbill (Rhyticeros everetti) dominated observed direct confrontations and was the most frequent visitor to active parrot nests, suggesting a further role as a potential nest-predator. Cockatoos prospected many cavities but rarely then attempted to nest: instead the sites were usually occupied by other cavity-nesters, or by bees. At the few cavities where cockatoos did breed, predation pressure was likely low, and observed success rate high (10 successful of 15 nests), although the low number of nests found early in the breeding cycle suggests that some may have failed before detection. Intense competition for cavities suggests a shortage of suitable nest-sites, the need for preservation of old hole bearing trees and a role for nestboxes. Accessible, known, safe artificial nest-sites would also provide opportunities to assess the scale of nest-site shortage, allow camera placements to study productivity, exclude some competitors and predators and prevent illegal trapping. Especially given continued trapping pressure, the species would benefit from targeted local awareness-raising and law enforcement, with the whole endeavour backed up by longer-term forest restoration.
... Although communal roosts provide estimates of population abundance for Amazona parrots in a variety of habitats (Howell 1999, Eisermann 2003, Cougill and Marsden 2004, Vaughan et al. 2005, Matuzak and Brightsmith 2007, Lee and Marsden 2012, Kiacz et al. 2020, it is difficult to determine the effective area used by congregated parrots and to transform counts into density. ...
Article
ABSTRACT—The Yellow-headed Parrot (Amazona oratrix) is considered globally endangered due to intense poaching pressure and extensive tropical forest loss. We examined the relationships among nesting pair density, survey area, tropical forest type, and forest conservation conditions to estimate the potential population size in central-western Mexico. The surveyed areas constitute a representative sample of forest types, property ownership, and land use in the region. We estimated the overall surveyed area and the nesting pairs in general and by each forest type. Data were analyzed in multiple and single linear regression models.We used a high-resolution vegetation model to measure the extent of each forest type and land use in the area with suitable climatic conditions for nesting. We recorded 111 nesting events in 77 distinct nest trees during the 2002–2013 study period in an area of 185.3 km2. Overall nesting density was 0.59 6 0.28 pairs per km2. Individual areas surveyed showed a broad variation in nest densities (0.14–1.5 per km2). Primary tropical semi-deciduous forest held 64% of the nesting pairs and the highest nesting density (1.98 6 0.82 per km2). Tropical dry deciduous forest contained 11% of nesting pairs and 0.20 6 0.19 pairs per km2. Single linear regression models by forest type performed better and are more practical for abundance calculations than multiple regression models. We estimate the size of the nesting population in the region at 701 pairs (95% CI: 526–876), which corresponds to about 1,399–2,330 parrots, using the mature/ immature ratio used by the IUCN. The results suggest that central-western Mexico may hold about 27% of the species’ global population.
... When possible, we also recorded with video in main flyways and/or colonial roosting areas. In secure areas, additional evening counts were conducted at sites where the birds congregated as in Jaumave, Tamaulipas, where macaws forage on nut trees (Eisermann 2003, Cougill and Marsden 2004, Vaughan et al. 2005, Bonilla-Ruz et al. 2007b, Matuzak and Brightsmith 2007. ...
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The preservation of Military Macaw Ara militaris in Mexico required the implementation of a nationwide assessment evaluating its vulnerability using IUCN criteria. With the combined effort of several institutions, the abundance, location, dispersion, habitat availability, and climatic conditions of areas occupied by the species were determined. Although the species’ extent of occurrence is extensive (263,919 km2) only 29% of this constitutes area of occupancy. Published estimates indicate a series of isolated populations containing from four macaws to 215. Macaws occurred in 35 populations in four regions of 16 states containing an estimated 1,563–3,263 macaws; lower than required for long-term viability. Within regions, neighbouring populations were separated by an average of 68 km. The extent of occurrence is heterogeneous, and macaws inhabit areas that differ in elevation, precipitation, temperature, and forest cover. Higher local abundances occur in landscapes where annual precipitation is ≥1,100 mm, and primary forest availability ≥1,800 km2. Although the existence of undetected macaw groups in Mexico is possible, these are likely to contain only small numbers of individuals, as most detected areas with macaws contain less than 40 individuals, and larger concentrations are more likely to be noticed due to their conspicuous behaviour. The species is threatened primarily by its low overall abundance, fragmented distribution, and forest loss around populations with the highest abundance. With the information generated, it is possible to design and implement specific management and conservation strategies at different geographic scales for the recovery and maintenance of the species in Mexico. It is necessary to strengthen collaborative programmes among conservation organizations, government agencies, and local communities in each region of the country to organize and finance community-based actions such as monitoring, habitat restoration, protection from poaching and the creation of a network of conservation corridors and macaw reserves focused on conservation.
... Roost count method is employed when population size of parakeets and parrots is small (Casagrande and Beissinger, 1997) and have many advantages over Point count and Line transects method. The counting of pre-and post-breeding measure of roosts can provide us an insight in the population size (Matuzak and Brightsmith, 2007). The Information Centre hypothesis for communal roost proposes that birds congregate at night to exchange information about some nearby feeding place (Ward and Zahvi, 1973). ...
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Rose-ringed parakeet (P. krameri) is commonly found native psittacid in Pakistan. It is most popular companion bird in Pakistan. It is an unprotected species as per The Punjab Wildlife Act, 1974. The objectives of the present study were to study its population paradigm and basic nesting biology in the Gujar Khan, Punjab, Pakistan. Previously, no studies were carried out to assess its live and vacant nest cavities, nesting site, nest height, cavity position on substrate, and potential roosts in the area. Moreover, this study also assesses the potential threats and factors in this area and conservation of the parakeet. Results show that in the study area (36.77%) active and (63.22%) inactive nests were found. A total of 10 tree species were utilized to make nests. It was found Ficus bengalensis, Syzygium cumini, Morus alba, Melia azedarach and Broussonetia papyrifera as the most used tree species for nesting due to more frequencies and old ages. Parakeets make nest at 3-11 m height. The preferred nest height (42.48%) was in the range of 7-9 m, while (5.88%) least at 3-5 m height. For safety reasons they made more nests (45.09%) on the tree trunk followed by terminal (31.37%) and at fork (23.52%). Due to smaller thriving population we found only (mean=7±4) parakeets during roost counting. Severe cutting of trees, destruction of its habitat and poaching for selling in the bird market are the main causes of its population decline. Government must change its status from unprotected to protected species and should ban its dealing for pet.
... Roost count method is employed when population size of parakeets and parrots is small (Casagrande and Beissinger, 1997) and have many advantages over Point count and Line transects method. The counting of pre-and post-breeding measure of roosts can provide us an insight in the population size (Matuzak and Brightsmith, 2007). The Information Centre hypothesis for communal roost proposes that birds congregate at night to exchange information about some nearby feeding place (Ward and Zahvi, 1973). ...
Article
Full-text available
Rose-ringed parakeet (P. krameri) is commonly found native psittacid in Pakistan. It is most popular companion bird in Pakistan. It is an unprotected species as per The Punjab Wildlife Act, 1974. The objectives of the present study were to study its population paradigm and basic nesting biology in the Gujar Khan, Punjab, Pakistan. Previously, no studies were carried out to assess its live and vacant nest cavities, nesting site, nest height, cavity position on substrate, and potential roosts in the area. Moreover, this study also assesses the potential threats and factors in this area and conservation of the parakeet. Results show that in the study area (36.77%) active and (63.22%) inactive nests were found. A total of 10 tree species were utilized to make nests. It was found Ficus bengalensis, Syzygium cumini, Morus alba, Melia azedarach and Broussonetia papyrifera as the most used tree species for nesting due to more frequencies and old ages. Parakeets make nest at 3-11 m height. The preferred nest height (42.48%) was in the range of 7-9 m, while (5.88%) least at 3-5 m height. For safety reasons they made more nests (45.09%) on the tree trunk followed by terminal (31.37%) and at fork (23.52%). Due to smaller thriving population we found only (mean=7±4) parakeets during roost counting. Severe cutting of trees, destruction of its habitat and poaching for selling in the bird market are the main causes of its population decline. Government must change its status from unprotected to protected species and should ban its dealing for pet.
... Sites where birds gather in large numbers to roost or use seasonal resources provide opportunities to monitor some bird populations. Seasonal changes in roost counts have been used to estimate the size and recruitment of threatened populations (Matuzak and Brightsmith 2007) and to provide information about population size and structure (Berg and Angel 2006). Monitoring over long periods of time is the only efficient tool to distinguish between natural fluctuations and those caused by human influence (Bibby et al. 1998). ...
Research
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Abstract - Macaw behaviour: Red-and-green macaws (Ara chloropterus) are one of the most commonmembers of the parrot family observed at large, riverside claylicks insouth-easternPeru.Although considered common and widespread in aviculture, little is known about their socialinteractions in the wild. Claylicks provide anideal setting at which to study wild birdbehaviour,with the caveat that the claylick itself may impact on social interactions. We observed macawsaround two claylicks in the lowland Amazon. Macaw behaviour differed significantly on thesurface of the claylick compared to the surrounding vegetation. The position of a bird in thesurrounding vegetation may also influence behaviour, with the canopy level associated morewith preening and inter-pair bonding interactions like allopreening. Aggression increasescloser to, and on the claylick, although a high degree of submissiveness appears toaccommodate bird proximity on the claylick itself. Whether aggression is a characteristic ofindividual macaws, or whether these interactions help establish a dominance hierarchy amongthe local population of macaws is unclear at this stage. In comparison to a control group ofscarlet macaws observed around nesting sites, macaws at the claylick appeared to bebothered less by insects. Playing, preening and aggression were all observed more around theclaylick compared to birds around nests. Lower vigilance and a comparable number ofaggressive interactions at a site with fewer red-and-green macaws and more scarlet macawsappears to indicate the interactions of these speciesas a “super flock” at this site. Ofconservation concern, it appears that a smaller proportion of birds will feed when there arefewer than ten macaws in the area of the claylick, highlighting the vulnerability of these sites tohuman and other disturbance. We suggest further studies of macaw claylicks to determineseasonal changes in behaviour; the role of claylicks in the social structure of the macaws; andhow these interactions are influenced by disturbances factors such as passing boat traffic.Seasonal patterns at claylicks: We present results from claylick monitoring studiesconducted at three sites in the lowland rainforest ofsouth-easternPeru in the department ofMadre-de-Dios, for the period 2005 to 2008. Red-and-green macaws are commonly observedaround riverside claylicks of the region, where they can be observed throughout the day.Seasonal patterns of claylick visitation by the macaws to the three claylicks show broadpatterns of similarity, but monthly feeding shows different patterns between the sites. Patternsof daily feeding also show different trends. Roosts and similar congregation sites for birds canbe used for monitoring populations and recruitment rates and we discuss the potential ofclaylicks for performing similar studies. We discuss the results in the context of a region facinglarge anthropomorphic change to increased human settlement of the region with the paving ofa major road through the region.Mammal survey:Neotropical game species are important ecologically and economically.Subsistence hunters depend on wild game for food, but local extinction of these species hasbroad effects on forest structure, plant diversity and predator populations.Previous researchhas addressed some of the effects of hunting on large game, however none have examinedthe synergistic effects of habitat factors, such as the presence of claylicks, in addition tohunting, that can affect game populations.We continued a multi-year dataset monitoringmammals and large-bodied birds after the cessation of logging and hunting activities at LasPiedras Biodiversity Station, Madre de Dios, Peru. We compared encounter rates of largemammals with distance to a mammal claylick. We also monitored two claylicks with cameratraps and one with human observers.The results of this study will facilitate betterunderstanding of the habitat requirements of these species, as well as their recovery afterdisturbance.This information will help guide future decisions regarding management ofNeotropical mammals andselection of protected sites. Resumen - Comportamiento de guacamayos:El guacamayo cabezon (Ara chloropterus) es uno de lamas común de las especies de loro que se encuentra cerca tierras salados de las orillas deríos (o colpas) del sureste de Perú. Auncomún en cuativario, existe poco información sobreinteracciones sociales en su estado silvestre. Colpas son sitios ideales donde se puedemonitorear comportamiento de aves silvestres, aun la presencia de la colpa misma puedetener un impacto en el comportamiento. Hicimos monitoreo de guacamayos alrededor de doscolpas en bosque de lluvia de la Amazona. Comportamiento de guacamayos estabasignificante diferente entre aves en los árboles y aves en la misma colpa. La posición del aveen la vegetación alrededor de la colpa también puede tener impacto en su comportamiento,con aves más alto observado más acicalándose y acicalando parejas. Agresión es elevadocon proximidad de la colpa y en la colpa misma, pero los guacamayos aguantan la presenciade vecinos consignos de sumisión. Si agresión es una característica de individuos o siinteracciones sirven como una manera de sustentar su posición de poder dentro de lacomunidad no es claro. Insectos molestan más a los guacamayos escarlatas alrededor de susnidos como los guacamayos alrededor de la colpa. Jugando, acicalándose y agresión seobserva más alrededor de la colpa que los nidos. Niveles bajo de vigilancia y un nivel deagresión comparable entre los dos colpas son indicaciones que los guacamayos cabezonesestán utilizando guacamayos escarlatas como parte de un “gran bandada”. Un punto depreocupación para su conservación, es que no hemos observado guacamayos colpeando conmenos de diez aves alrededor de la colpa, que puede indicar un número mínimo para esaactividad. Sugerimos mas estudios de comportamiento para entender el impacto deestaciones y como botes son fuente de perturbación.Patrones estacionales alrededor de colpas: Presentamos resultados del monitoreo de trescolpas de la selva del Perú sureste, de observaciones hecho entre 2005 y 2008. Guacamayoscabezones (Ara chloropterus) se encuentra frecuentemente alrededor de colpas de ríos de laregión, donde se paran por muchas horas durante del día. Patrones estacionales entre lastres colpas son aparentemente parecidos, pero cambios entre meses son diferentes. Patronesde visitas a la colpa también son distintos entre las colpas. Dormideros y lugares similaresdonde se encuentra gran cantidades de aves puede ser herramientas para el monitoreo depoblaciones y consideramos la potencial de colpas para hacer estudios similares. Discutimoslos resultados en el contexto de cambios de gran escala que viene a propósito de la carreterainteroceánica que va a resultar en altos niveles de migración de humanos a la zona.Estudio de mamíferos:Especies Neotropicales frecuentemente cazados son importantesecológicamente y económicamente. Mitayeros depende de esas especies para comida, peroextinción de esas especies tiene gran impactos en la estructura de los bosques,diversidad deplantas, y poblaciones de depredadores. Investigaciones anteriores han discutido algunas deesos impactos, pero ninguno se ha enfocado en el impacto de tipos de bosque, presencia decolpas además que el impacto de mitayeros que puede impactar poblaciones de animales.Continuamos el monitoreo largo plazo de mamíferos y aves grandes después de una épocade casaría en los bosques alrededor del Las Piedras Biodiversity Station, Madre de Dios,Perú. Hicimos comparaciones entre tipos de encuentrode mamíferos con distancia de colpas.Hicimos monitoreo de colpas con trampas cameras y observaciones visuales deobservadores. Los resultados son útiles para el conocimiento de uso de tipos de bosque porlos mamíferos, y muestran recuperación de poblaciones de algunas especies después de sercasados. Esa información sirve como un guía para el manejo de mamíferos Neotropicales deáreas protegidas
... During another Red-tailed Amazon study, researchers found that 18% of groups flying to a roost consisted of three or more birds (Cougill and Marsden 2004). Similarly, two studies of Yellow-naped Amazon showed a 24% (Wright et al. 2019) and 18% (Matuzak and Brightsmith 2007) rate of groups of three or more attending roosts. If we assumed these groups of three or more were successfully fledgling two young apiece (as RCAM average; Enkerlin-Hoeflich 1995), these three populations would be averaging about 19% (Red-tailed Amazon), 15%, and 15% (Yellownaped Amazon) juveniles, respectively. ...
Article
Newly established populations of endangered species can help mitigate declines elsewhere and can be a valuable genetic reservoir. When these populations are located within anthropogenic habitats, they may also help mitigate the potential biodiversity loss created by urbanization. The Red-crowned Amazon Amazona viridigenalis is an endangered species that has become naturalized in multiple urban areas throughout the United States and Mexico, and these populations may currently outnumber the population within their historical habitat. While these urban populations may hold the majority of this endangered species, very few studies have analyzed the status and trends of this species, or of threatened parrots in general, in urban areas. Our study focuses on an urban Red-crowned Amazon population in the Lower Rio Grande Valley (LRGV) of Texas: the only parrot population currently recognized as native to the United States. To determine a timeline of Red-crowned Amazon arrival and growth in the LRGV, we reviewed published literature and online citizen science databases. To quantify current population levels and trends, we conducted 412 surveys at all known roost sites throughout the LRGV from January 2016 through April 2019. We also quantified the ratio of adult and juvenile parrots at roosts. Our data suggest the species has been present in the LRGV consistently since the 1970s and showed rapid growth from the mid-1990s through roughly 2016. Roost counts suggest there is currently a minimum LRGV population of about 680 and the population has been relatively stable over the last 3.5 years. Productivity averaged 19% over three breeding seasons, suggesting successful internal reproduction. This study provides important baseline information for the management and conservation of Red-crowned Amazons in the region and provides a valuable timeline on the beginnings and trends of this recently established urban population of Amazona parrot.
... When August begins, there are virtually no parrots left at communal roosts and the population is once again dispersed across hundreds of nesting sites. Despite difficulties inherent to locating roosts and counting the number of individuals, roost counts remain one of the most popular and cost-effective ways of assessing the abundance of parrots (Matuzak and Brightsmith, 2007;Dénes et al., 2018). ...
Article
Population size is a key predictor of extinction risk and is critical to listing species in IUCN threat categories. Assessing population size can be particularly difficult for gregarious species, such as parrots—one of the most threatened bird families—whose ecology and behavior generate multiple sources of uncertainty that need to be addressed in monitoring efforts. To improve estimates of abundance for the endangered Vinaceous-breasted Parrot (Amazona vinacea), we combined extensive roost counts over the global range of the species (Argentina, Paraguay, Brazil) with an intensive regional survey designed to address five sources of uncertainty about parrot abundance in western Santa Catarina state (WSC), Brazil, in 2016 and 2017. We estimated abundance at both regional and whole-range scales using N-mixture models of replicated count data, which account for imperfect detection. The regional-scale estimate was 1826 ± 236 and 1896 ± 105 individuals for 2016 and 2017, respectively; global abundance was estimated at 7789 ± 655 and 8483 ± 693 individuals for the same two years. We found no statistical evidence of population change at either scale of the analysis. Although our assessments of abundance and geographic range are larger than those currently reported by the IUCN, we suggest the Vinaceous-breasted Parrot should remain in the ‘Endangered’ IUCN threat category pending further investigation of population trends. We recommend that roost-monitoring programs for parrots consider and address sources of uncertainty through adequate field protocols and statistical analyses, to better inform assessments of population size, trends, and threat status.
... Most aspects of their life history, behavior, and ecology have not been systematically assessed in wild populations. Matuzak and Brightsmith (2007) estimated that the breeding season of Yellow-naped Amazons in Costa Rica was from December through March, and Joyner et al. (2016) found that nestlings fledged in December and January on the Nicaraguan island of Ometepe. In Costa Rica, a study of radio-tagged Yellow-naped Amazons revealed preferences for savannah and riparian habitats (Salinas-Melgoza et al. 2013). ...
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The population of Yellow-naped Amazons (Amazona auropalliata) declined by an estimated 50% between 1980 and 2000, and the current population is estimated to be between 10,000 and 50,000. Poaching of young has been a persistent problem, but the species is also threatened by habitat loss and degradation. Because most aspects of their life history, behavior, and ecology have not been examined in wild populations, we studied Yellow-naped Amazons with the following objectives: (1) identify the species of trees used for nesting, (2) determine the size and potential function of breeding territories, (3) determine nesting success, and (4) examine their duetting behavior. We located nests at 16 sites on the Pacific Slope of Costa Rica from 1999 to 2008. We searched for nests from January to May. Every nest was visited at least once and some nests were visited every 2–3 weeks throughout the breeding season. We also collected territory and duetting data at one site (Ahogados). The breeding season of Yellow-naped Amazons was during the dry season (January–May). Yellow-naped Amazons nested in 21 species of trees, but 68% of nests were located in only five species, and cavities in dead coyols (Acrocomia aculeata) were used most often. We found no association between breeding success and the species of tree in which birds nested. Mean territory size was 25,578 m², and these small areas generally consisted of several trees surrounding a nest tree. Pairs continued to duet throughout the breeding season, suggesting that duetting is important for territory defense. The nest failure rate in our study was 89%, and most nest failures (64%) were due to poaching for the pet trade. We recommend immediate population management and conservation actions, including increased law enforcement to reduce nest poaching, protection of key nesting areas, educational programs, and habitat conservation.
... Nombre investigador, localidad, fechas, Carlos Bonilla: noroeste de Oaxaca, México, en los municipios de Jocotipac, Cuicatlán y Tecomavaca. 2002al 2007 Costa Pacífica de Jalisco, en la zona de influencia de Bahía de Banderas. 2008. ...
... Para obtener información sobre cronogramas y tasas de reproducción de P. couloni documentamos los tamaños de grupos mientras pasaron por la zona y cuando arribaron a la collpa. Especies de loros grandes de los géneros Amazona, Ara, y afines incluyendo Primolius normalmente viajan en grupos familiares y cambios a través del año en tamaño de grupos pueden servir como información indirecta sobre patrones reproductivos (Munn 1992, Matuzak & Brightsmith 2007. Las observaciones se realizaron desde las 04:30 h hasta las 08:00 h entre enero y octubre 2006 durante días de buen clima (e.g. ...
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The Blue-headed Macaw is an uncommon species endemic to the southwestern Amazon basin. Currently classified as 'Vulnerable' by the IUCN there is relatively little known about its ecology, habitat use, breeding season, and clay lick use. Here we report on observations of the species during a 10-month study conducted in foothill forest habitat in southeastern Peru. The Blue-headed Macaw used peripheral sections of a local clay lick along with small groups of Chestnut-fronted Macaw (Ara severus) and Dusky-headed Parakeet (Aratinga weddellii), but not the main section of the lick with larger groups of mixed psittacines. Mean group size for the species in flight was 2.6 +/- 2.2 of which 60% were groups of two. Lone birds were most commonly recorded in September and October. Based on the seasonal change in the proportion of lone birds suggests that approximately 6% of the population may have been males with females incubating in nests. Most of the individuals were seen coming from the east in the early morning. This observation along with the comments of the local people suggests that the species utilizes small farms and pastures located along the edge of rivers for roosting habitat.
... The magnitude of changes in flock size between seasons was minimal. This small difference (lower in the "rainy season" than in the "end of rainy season") can be explained by the recruitment of nestlings after the reproduction period (Pizo 2002, Matuzak andBrightsmith 2007) that is in the "end of rainy season" from April to July Novaes 1986, Laranjeiras 2008a). The species remains in large flocks throughout the whole year -including the breeding season -confirming previous observations (Oren and Novaes 1986). ...
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Golden Parakeets are a poorly known, endangered parrot endemic to the Brazilian Amazon. I describe the flocking patterns, the diet and nest sites of this species and estimate the abundance and size of its population in western Pará. During 2007, I spent about 500 hrs searching for flocks and making transect surveys. Golden Parakeets maintained family flocks of about 10 individuals throughout the year, confirming previous observations. My estimate of reproductive output from the proportion of first year juveniles in the flocks (around 13%) is within the range of estimates found for other parrots, suggesting a normal reproductive output. Feeding bouts (n = 82) confirmed a diversified diet that varies throughout the year, but some items (e.g., Byrsonima spp.; Tapirira guianensis) seem to be more important. All found nest trees were in open areas, adjacent to the continuous forest, exposed to the human disturbance, indicating a potential vulnerability. Surveys indicated that the Golden Parakeet is as common as other sympatric and non-threatened parrots, contrary to expectations. The species probably occupies the whole study region (a strip of about 340 km along the Tapajós river) with an estimated population size of about 500 individuals comprising the largest known population. My data and recent records of the species indicate that its global population size is larger than previously estimated and its official level of endangerment in the red lists should be re-examined.
... Differences in fission-fusion group dynamics are hypothesized to drive some of the differences observed between species, such as geographic variation in parrot vocalizations (Cortopassi and Bradbury 2006). Parrots are also likely to exhibit seasonal shifts in fission-fusion dynamics because many species reduce communal roosting behaviors during the breeding season (Juniper and Parr 1998, Harms and Eberhard 2003, Cougill and Marsden 2004, Matuzak and Brightsmith 2007, de Moura et al. 2010. Future research into the costs and benefits of fission-fusion patterns may provide insight into the factors driving fission-fusion dynamics and social structure. ...
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In many species, individuals benefit from social associations, but they must balance these benefits with the costs of competition for resources. Understanding how these competing factors generate diversity in social systems is a major goal of behavioral ecology, but one that has been hampered by a lack of basic data quantifying many aspects of social structure and associations. Although parrots are generally assumed to have complex social groups, few studies have quantitatively examined these assumptions about parrot social structure. We critically assessed 4 assumptions about parrot socioecology using data from captive and wild groups of Monk Parakeets (Myiopsitta monachus). We evaluated (1) whether pairs are the fundamental unit of parrot social structure, (2) the patterns and extent of fission–fusion dynamics, (3) patterns of aggression and dominance hierarchy structure, and (4) whether individuals share foraging information. We found evidence that supported pairs as the fundamental unit of social structure, although these close associates were not always heterosexual breeding pairs and were sometimes trios. Fission and fusion of subgroups were common, and the amount of fission–fusion dynamics varied across flock types and by fission–fusion dimension, but the amount of variation among dimensions was consistent across replicate captive social groups. Despite these levels of fission–fusion dynamics, study of aggressive interactions in our 2 captive groups indicated that dominance hierarchies existed. Hierarchies were moderately linear (0.7) but not steep (
... The post-breeding proportion of juveniles is used as an indirect measure of breeding productivity when direct estimates are not feasible (e.g., Matuzak and Brightsmith, 2007;Carrete et al., 2009b). Juvenile red-fronted macaws are easily identified by their lack of bright red-orange patches on their front and shoulders typical of adults (Juniper and Parr, 2010). ...
... Data analyzes. Because Amazons perform daily trips from communal roots to feeding areas (Berg and Angel, 2006;Matuzak and Brightsmith, 2007;Ragusa-Netto, 2011), where the density of fruit patches may vary, and taking into account that predators should concentrate their activities in sites where foraging success is expected (Schupp, 1988), I tested the relationship between individual fruit crop size and the chance of crop damage by Amazons through logistic regression, in which individual fruit crop size was coded as 0 (undamaged), or 1 (damaged by amazons). To analyze the relationship between fruit crop size and either the number of damaged fruits or proportional crop loss to Amazons, as well as the relationship between proportional crop loss and the distance to the nearest depredated conspecific, I applied linear regression. ...
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Seed predation has major effects on the reproductive success of individuals, spatial patterns of populations, genetic variability, interspecific interactions and ultimately in the diversity of tree communities. At a Brazilian savanna, I evaluated the proportional crop loss of Eriotheca gracilipes due the Blue-Fronted Amazon (Amazona aestiva) during a fruiting period. Also, I analyzed the relationship between proportional crop loss to Amazons and both fruit crop size and the distance from the nearest damaged conspecific. Trees produced from 1 to 109 fruits, so that Amazons foraged more often on trees bearing larger fruit crop size, while seldom visited less productive trees. Moreover, the relationship between fruit crop sizes and the number of depredated fruits was significant. However, when only damaged trees were assessed, I found a negative and significant relation between fruit crop size and proportional crop loss to Blue-Fronted Amazons. Taking into account this as a measure more directly related to the probability of seed survival, a negative density dependent effect emerged. Also, Amazons similarly damaged the fruit crops of either close or distant neighboring damaged trees. Hence, in spite of Blue-Fronted Amazons searched for E. gracilipes bearing large fruit crops, they were swamped due to the presence of more fruits than they could eat. Moderate seed predation by Blue-Fronted Amazons either at trees with large fruit crops or in areas where fruiting trees were aggregated implies in an enhanced probability of E. gracilipes seed survival and consequent regeneration success.
... While not always well suited to tropical conditions and parrots, we suggest that they remain the best option for parrot ecologists outside situations in which total counts can be made, or perhaps where roost counts are feasible (e.g. Matuzak & Brightsmith 2007). There have also been recent advances in tailoring distance sampling methods to individual situations such as tall, structurally complex Amazonian forests, through the use of a cue-counting variant of line transects (Lee & Marden 2012). ...
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Estimates of population density and abundance change (differences in density or encounter rates across land uses or time periods) form the cornerstone of much of our knowledge of species’ responses to environmental conditions, extinction risks and potential conservation actions. Gathering baseline data on abundance of the world's c. 10 000 bird species and monitoring trends in the light of rapidly changing environmental and harvest pressures is a daunting prospect. With this in mind, we review literature on population densities and abundance changes across habitats in one of the world's largest and most threatened bird families, the parrots (Psittaciformes), in order to identify gaps in knowledge, model phylogenetic and other influences on abundance and seek patterns that might guide thinking for data-deficient taxa and situations.This article is protected by copyright. All rights reserved.
... The post-breeding proportion of juveniles is used as an indirect measure of breeding productivity when direct estimates are not feasible (e.g., Matuzak and Brightsmith, 2007; Carrete et al., 2009b). Juvenile red-fronted macaws are easily identified by their lack of bright red–orange patches on their front and shoulders typical of adults (Juniper and Parr, 2010). ...
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The IUCN Red List is challenged with assessing the conservation status of species on which reliable demographic and distribution parameters are lacking. The hotly debated SAFE index, however, measures the ''species' ability to forestall extinction'' and only requires information on population size. Nonetheless, both conservation assessment systems neglect the role of non-breeding population fractions in conservation. We conducted simple surveys to ascertain the spatial and population structure and conservation threats of the Endangered red-fronted macaw Ara rubrogenys, endemic to the Bolivian Andes. The area of occupancy (ca. 2600 Km 2) encompassed eight breeding and six non-breeding areas, occupied by 807 individuals. By combining population-fraction censuses with the proportion of juveniles (8.6%), we inferred a breeding population of less than 100 pairs clumped in 38–40 nesting sites, with non-breeders representing ca. 80% of the population. While this increase in data quality raises questions as to whether the species should be upgraded to Critically Endangered, the SAFE index rendered questionable guidance for conservation triage. Conservation threats were spatially identified according to spatio-temporal and life-stage population structures and seasonal changes in habitat use. Several sources of habitat loss were widespread but, contrary to expectation, habitat-use models indicated that red-fronted macaws were not tied to forest remnants. Instead, they made use of agricultural lands resulting in conflicts with farmers. Awareness campaigns should focus on a few selected locations to resolve this conflict and reduce the uptake of individuals for use as pets, as the most effective way to increase population size in the medium term .
... The energy contents of each plant species were then used to estimate the number of seeds required by Cockatoos to meet their field metabolic energetic requirements of 726 kJ d 21 , as estimated by Cooper et al. [29]. To determine trends in the abundance of Carnaby's Cockatoos using the Gnangara plantations, we counted the number of birds occupying known over-night roost sites [7,30]. From February to September 2009, observers conducted simultaneous roost counts once a week at 14 known roost sites located in or around the plantations ( Figure 1). ...
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... To determine trends in the abundance of Carnaby's Cockatoos using the Gnangara plantations, we counted the number of birds occupying known over-night roost sites [7,30]. From February to September 2009, observers conducted simultaneous roost counts once a week at 14 known roost sites located in or around the plantations (Figure 1). ...
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Pine plantations near Perth, Western Australia have provided an important food source for endangered Carnaby's Cockatoos (Calyptorhynchus latirostris) since the 1940s. Plans to harvest these plantations without re-planting will remove this food source by 2031 or earlier. To assess the impact of pine removal, we studied the ecological association between Carnaby's Cockatoos and pine using behavioural, nutritional, and phenological data. Pine plantations provided high densities of seed (158 025 seeds ha 21) over a large area (c. 15 000 ha). Carnaby's Cockatoos fed throughout these plantations and removed almost the entire annual crop of pine cones. Peak cockatoo abundance coincided with pine seed maturation. Pine seed had energy and protein contents equivalent to native food sources and, critically, is available in summer when breeding pairs have young offspring to feed. This strong and enduring ecological association clearly suggests that removing pine will have a significant impact on this endangered species unless restoration strategies, to establish alternative food sources, are implemented. Citation: Stock WD, Finn H, Parker J, Dods K (2013) Pine as Fast Food: Foraging Ecology of an Endangered Cockatoo in a Forestry Landscape. PLoS ONE 8(4): e61145.
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Yellow-naped amazons, Amazona auropalliata, have experienced a dramatic population decline due to persistent habitat loss and poaching. In 2017, BirdLife International changed the species’ status from threatened to endangered and estimated that between 10,000 and 50,000 individuals remained in the wild. An accurate estimate of the number of remaining wild individuals is critical to implementing effective conservation plans. Wright et al. conducted roost count surveys in Costa Rica and Nicaragua during 2016 and published their data in 2019; however, no population data exists for the rest of the range. We conducted roost counts at 28 sites across Mexico, Guatemala, and the Bay Islands in Roatan during 2018 and 2019. We counted 679 birds and combined our data with the published Wright et al. (2019) data for a total of 2361 wild yellow-naped amazons observed across the species’ range. There were fewer roosts detected in the northern region of the range than in the southern region. We found that roosts were most likely to occur in built-up rural and pasture habitat, with 71% found within 100 m of human habitation. Our results illustrate the need for immediate conservation action to mitigate decline, such as enforced legal action against poaching, nest guarding, and increased community education efforts.
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We studied nest sites, nesting success, chick productivity, and social behavior of the Military Macaw (Ara militaris) in perhaps the last population that nests in tree cavities in tropical coastal forest near Puerto Vallarta, Mexico. Thirteen nest trees were located in five tree species, but most nesting pairs used Piranhea mexicana (Picrodendraceae). Three nest trees contained multiple nesting pairs; one tree contained three pairs nesting simultaneously. Nesting trees were located in three vegetation types, but tropical semideciduous forest contained 75% of the nests, yielding a nesting tree density of 2.0/km(2) and a nesting pair density of 3.0/km(2). We systematically monitored seven nests all within tropical semideciduous forest. All seven monitored nests succeeded and produced an average of 1.28 chicks that reached fledging age. However, we were unable to monitor hatching and fledging success, although no signs of predation were evident in the surroundings. Although the sample size of nests is small, reproductive performance and tree and forest characteristics allowed us to hypothesize that this macaw population is nesting in an area that likely contains the highest quality among all the studied Military Macaw populations in Mexico. It is essential to outline with precision the forest extent containing suitable nesting conditions, as well as the nesting population size. The observed nesting tolerance may facilitate management and conservation actions for the species in the region, offering opportunities to design environmental education initiatives compatibles with ecotourism. Urgent conservation measures include a total prohibition of logging of all large emergent live and decaying trees in the region; ideally, the area should be designated as wildlife sanctuary for habitat protection of endangered species.
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Abstract. – Gregarious nesting and reproductive success in the Military Macaw (Ara militaris) in a coastal tropical forest in Western Mexico. – We studied nest sites, nesting success, chick productivity, and social behavior of the Military Macaw (Ara militaris) in perhaps the last population that nests in tree cavities in tropical coastal forest near Puerto Vallarta, Mexico. Thirteen nest trees were located in five tree species, but most nesting pairs used Piranhea mexicana (Picrodendraceae). Three nest trees contained multiple nesting pairs; one tree contained three pairs nesting simultaneously. Nesting trees were located in three vegetation types, but tropical semideciduous forest contained 75% of the nests, yielding a nesting tree density of 2.0/km2 and a nesting pair density of 3.0/km2. We systematically monitored seven nests all within tropical semideciduous forest. All seven monitored nests succeeded and produced an average of 1.28 chicks that reached fledging age. However, we were unable to monitor hatching and fledging success, although no signs of predation were evident in the surroundings. Although the sample size of nests is small, reproductive performance and tree and forest characteristics allowed us to hypothesize that this macaw population is nesting in an area that likely contains the highest quality among all the studied Military Macaw populations in Mexico. It is essential to outline with precision the forest extent containing suitable nesting conditions, as well as the nesting population size. The observed nesting tolerance may facilitate management and conservation actions for the species in the region, offering opportunities to design environmental education initiatives compatibles with ecotourism. Urgent conservation measures include a total prohibition of logging of all large emergent live and decaying trees in the region; ideally, the area should be designated as wildlife sanctuary for habitat protection of endangered species.
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The diet of the Scaly-headed Parrot (Pionus maximiliani) was studied during three consecutive years in a 250 ha semideciduous forest in southeastern Brazil. The parrots showed a generalist and seasonal diet. Seeds composed 70.4 percent of the diet of parrots, followed by flowers (20.3%), corn from plantations that surround the forest (7.7%) and fruit pulp (1.6%). In the dry season flowers constituted 38 percent of the diet and leguminous fruits comprised 41.2 percent of its diet. Parrots are important predispersal seed predators and have a high impact on the fitness of plants in semideciduous forests, due to their high consumption of seeds and flowers.
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The relationship between cultural and genetic evolution was examined in the yellow-naped amazon Amazona auropalliata. This species has previously been shown to have regional dialects defined by large shifts in the acoustic structure of its learned contact call. Mitochondrial DNA sequence variation from a 680 base pair segment of the first domain of the control region was assayed in 41 samples collected from two neighbouring dialects in Costa Rica. The relationship of genetic variation to vocal variation was examined using haplotype analysis, genetic distance analysis, a maximum-likelihood estimator of migration rates and phylogenetic reconstructions. All analyses indicated a high degree of gene flow and, thus, individual dispersal across dialect boundaries. Calls sampled from sound libraries suggested that temporally stable contact call dialects occur throughout the range of the yellow-naped amazon, while the presence of similar dialects in the sister species Amazona ochrocephala suggests that the propensity to form dialects is ancestral in this clade. These results indicate that genes and culture are not closely associated in the yellow-naped amazon. Rather, they suggest that regional diversity in vocalizations is maintained by selective pressures that promote social learning and allow individual repertoires to conform to local call types.
Article
Many birds, including some parrots, may adjust the sex ratio of their offspring in relation to the relative fitness benefits of sons and daughters. We investigated nestling sex ratios in Yellow-naped Amazons (Amazona auropalliata) using a molecular sexing technique that amplifies intronic regions of the CHD-W and CHD-Z genes in birds. We examined all nestlings in 37 complete clutches comprising 77 chicks. The overall nestling sex ratio did not differ from unity. Sex allocation was not associated with hatch date, sequence of hatching, or clutch size. We also found no difference in sex ratio between two regional dialects. Female Yellow-naped Amazons may be unable to control their hatchling sex ratio. Alternatively, there may be no fitness benefits to females producing more of one sex in relation to the factors we measured here. No Existe Evidencia que Indique Modificaciones Adaptativas de la Proporción de Sexos en la Progenie de Amazona auropalliata Resumen. En muchas aves, incluyendo los loros, la proporción de sexos en la progenie puede ajustarse en relación a los beneficios relativos de adecuación biológica de hembras y machos. Dichas tasas fueron investigadas en Amazona auropalliata por medio de una técnica molecular de determinación sexual por la cual se amplifican regiones intrónicas de los genes CHD-W y CHD-Z de aves. Se examinaron todos los pichones de 37 nidadas completas, constituidas por 77 pichones. La proporción de sexos total no resultó diferente a uno. La asignación sexual no estuvo correlacionada con la fecha de eclosión, la secuencia de eclosión, ni el tamaño de la nidada. Tampoco se encontraron diferencias en las proporciones de sexos entre dos dialectos vocales regionales. Las hembras de A. auropalliata podrían no tener la habilidad de controlar la proporción de sexos de su progenie. Alternativamente, es posible que en términos de adecuación biológica, no haya diferencia en el beneficio de producir una progenie enriquecida en un sexo determinado con respecto a los factores medidos en este estudio.
Article
Roost counts may be a useful method for assessing and monitoring parrot populations as long as counting regimes can detect real differences in abundance above the noise of daily variability in roost size. We studied a roost of up to 85 Red-tailed Amazons (Amazona brasiliensis) for 28 consecutive mornings and evenings from 12 July to 7 August 2001, and recorded bird behavior and associated weather data. The roost declined significantly over the survey period as the breeding season drew nearer. There was no significant difference between evening and morning roost counts, but we suggest that as long as misty mornings are avoided, morning roost counts were more effective as birds left more quickly and predictably. It took longer for birds to arrive on evenings when the roost was large, but birds left quicker in the morning when there were large numbers in the roost. Weather influenced both roost size and timing of arrival, with larger than expected numbers in the roost, and birds arriving later in the afternoons of sunny, warm days. We tested the reliability of four roost counting regimes: counts from five consecutive nights, five counts, one every fourth night, five nights picked at random, and 10 randomly picked nights. Counts from every fourth day performed significantly worse than all the other regimes in estimating the mean numbers in the roost. The 10-d random sampling regime performed significantly better than the 5-d regime in detecting very large roosts which occurred occasionally through the month.
Article
During 1969-70, 185 tree species at a Wet forest site and 113 species at a Dry forest site in Costa Rica were systematically observed for changes in leafing, flowering and fruiting. (1) At the Wet forest site, the greatest amount of leaf fall in the overstorey and understorey trees occurred primarily during the first (more severe) dry season. At that time, 17% of the tree species from both storeys lost leaves. (2) At the Dry forest site, the period of greatest leaf fall coincided with the long dry period; at that time 75% of the species lost leaves. (3) Most Wet forest species flushed large quantities of new leaves during the first dry season. This was in contrast to the Dry forest site where most species flushed leaves at the onset of the first rainy season. (4) Two apparent flowering peaks in the overstorey tree species and three apparent flowering peaks in the understorey tree species were recorded during the year at the Wet forest site. These major flowering periods in both layers occurred during wet as well as dry seasons, and two of the peak periods of the overstorey appeared to be out of phase with two of the understorey. The species at the Wet forest site were well represented by both `seasonal' and `extended' flowering species. (5) At the Dry forest site, two peak periods of flowering activity were recognized. One extensive period occurred during the long dry season and a second peak period was recorded at the onset of the rainy season. Most species were of a `seasonal' rather than `extended' flowering nature. (6) With regard to Wet forest fruiting, substantial numbers of species (at least 37) from both storeys were in mature fruit during each month, but a peak in fruiting occurred in both layers during the second dry season (August-October); the fruiting peaks of the two storeys were separated by one month. The disseminules of most Wet forest species were not adapted for wind dispersal. (7) A peak period in the production of mature fruit occurred during the latter part of the long dry season at the Dry forest site. A significant proportion (31%) of the Dry forest species had disseminules adapted for wind dispersal. (8) When phenological patterns of vicarious species of the two forests were compared, only flowering patterns showed similarity (11/27 species). Leafing and fruiting patterns of vicarious species tended to follow the general trends of the respective forest ecosystems. (9) Periodicity patterns of most species in common between the two forest sites were similar. (10) The phenological patterns recorded are discussed in relation to climatic `triggers' (proximate factors) and plant-animal interactions (ultimate factors).
Article
Many types of biological studies require the estimation of food abundance in tropical forests, and a variety of methods have been used to estimate this parameter. Here we compare the accuracy and precision of three methods for estimating the fruit abundance (biomass and number) of tropical tree species: tree diameter, crown volume, and visual estimation. Diameter at breast height (DBH) was the most consistently accurate method and exhibited low levels of interobserver variability. Generally, crown volume was neither precise nor accurate. The visual estimation method was accurate for trees with very large fruit, but exhibited high interobserver variability.
Article
We used radio-telemetry techniques to determine hourly activity patterns of 29 juvenile Lilaccrowned Parrots (Amazona finschi) during 1996-2000 in tropical dry forest of Jalisco, Mexico. Parrots had two peak activity periods--early morning and local movement. Individuals were generally inactive and did not change location for 5-6 hr during the middle of the day. Parrots were more active in the dry season than in the rainy season, although movements resulting in a change of location did not vary between seasons. Seasonal variations in activity of Lilac-crowned Parrots may be related to variations in food availability or temperature. Activity patterns of parrots need to be considered when evaluating habitat use or survey data.
Article
A five-month study of the Red-fronted Macaw Ara rubrogenys, endemic to Bolivia, yielded a population estimate of 2,000–4,000 individuals. The species is resident and locally common in, but restricted to, an area in the drainage systems of the Rio Grande, Rio Mizque and northern Rio Pilcomayo. One-third of the population was composed of juveniles some three months after the end of the breeding season. During the dry season, with food apparently short, more of the day was spent feeding than during the wet season. Semi-deciduous vegetation along the rivers produced fruits and seeds that sustained the macaws during the dry season, but the conversion of such areas to arable land forces the macaw to depend for some months on crops and weeds. Local farmers consider the macaw a serious pest on maize.
Article
Data from roosts of Amazona parrots may be useful in creating demographic models, because these birds exhibit high roost fidelity and pairs are conspicuous in flight. However, few investigators have attempted to track changes in the number of pairs using such roosts. We studied Red-lored Amazons (Amazona autumnalis) at a communal roost in southwest Ecuador over a 1-yr period to understand better their population structure. Population size was estimated at 214 individuals. Counts revealed seasonal variation in numbers, but the occurrence of pairs and singles was seldom correlated. The number of paired individuals using the roost was lower during the breeding period. In contrast, the number of single birds at the roost nearly doubled during the breeding period. Overall, our data suggest that parental responsibilities during the nesting period explain fluctuations in the number of birds at the roost, and such fluctuations can be used to estimate the reproductive portion of the population. Protection of the small mangrove islands where the parrots roost would likely benefit a population that occupies a much larger area and would, at the same time, provide a useful tool for demographic studies of this poorly known neotropical parrot.
Article
We explored patterns of flight activity, flocking, and habitat use in a diverse community of parrots in an Amazonian lowland forest. Parrots were most active just after sunrise with a second peak of flight activity following a mid-day lull. Brotogeris spp. were exceptional, being most active in the early afternoon. Among the nine genera studied, we observed marked differences in where the birds flew relative to the canopy. Body size was a poor predictor of flight height, although it was strongly and inversely correlated with flock size. Most parrot species flew in groups of one to four individuals, suggesting that mated pairs are stable and that family groups remain together post-fledging. Flocks were exclu-sively monospecific except when the birds were foraging in trees or eating soil at clay licks. These forest-dwelling parrots did not show dramatic increases in flock size in the evening, reflecting the lack of communal and multispecies roosting observed in other parrots. Gen-erally, the large-and mid-sized species of parrots were associated with high-ground forest, whereas smaller species favored transitional forest. Because daily ranging patterns for these parrots potentially include all habitats, these patterns of habitat use suggest selection for subtle differences among forest types. As expected, smaller species were less detectable at a distance than large species. Comparisons of size and detectability indicate that macaws can be reliably counted to a distance of 300 m, but 100 m may be more appropriate for the smaller and low-flying genera. In sum, we found that observing parrots from the canopy is a useful method for quantifying parrot activities in a closed-canopy system, and that these forest-dwelling parrots are markedly less social than their counterparts on islands and in more open habitats. Patterns of flight behavior, habitat preferences, and the body size to flock size relationship invite further studies on the roles of predation and resource availability in the structuring of parrot communities.
Article
The pattern of food resource availability and use by Lilac-crowned Parrots (Amazona finschi) was evaluated in tropical dry forest of the Reserva de la Biosfera Chamela-Cuixmala, western Mexico. Monthly fruiting phenology transects were conducted throughout the year in deciduous and semi-deciduous forest to determine temporal and spatial variability in resource abundance. Resource use by parrots was evaluated through observations of diet and habitat use. There was significant temporal and spatial variability in food resource abundance, with semi-deciduous forest providing greater food resources for parrots during the dry season, whereas food resource abundance increased in deciduous forest during the rainy season. The critical period of food resource scarcity occurred during May-June at the end of the long dry season. Lilac-crowned Parrots were pre-dispersal seed predators, and exhibited high flexibility in diet, incorporating dietary switching, as well as niche-breadth contraction and expansion, which corresponded with temporal variations in food resource availability. There was low overlap in parrot diets between seasons, with parrots exhibiting a narrow food niche-breadth during the late dry season when resource availability declined. Parrots also demonstrated spatial variation in habitat use, corresponding to fluctuations in the availability of food resources in different habitats. This flexibility in foraging enables parrots to closely track and exploit seed resources which exhibit high temporal and spatial variability in abundance.
Article
Psittaciformes are generally believed to be long-lived birds and are frequently said to reach ages of 100 years old or more. In reality, however, life spans rarely exceed 50 years of age, although a few reliable records exist of parrots aged up to 65–70 years. Cockatoos appear to have the highest longevities and the longest reproductive life spans. Larger psit-tacines are generally longer-lived than smaller ones, although there seem to be some exceptions to this trend and quite remarkable differences in longevity between some similar-sized parrot genera. Some particularly interesting longevity histories, information on maximum breeding ages and trends in longevity are discussed.
Article
Growth rate parameters were analysed for Lilac-crowned Parrot Amazona finschi nestlings in the tropical dry forest of the Reserva de la Biosfera Chamela-Cuixmala, Mexico. Growth rates for psittacine species follow the inverse relation with body mass observed for neotropical landbirds, with larger parrot species exhibiting slower growth rates. There was significant variation between years in size and growth rates of Lilac-crowned Parrot nestlings with nestlings exhibiting slower growth rates in 1996 than in 1997. Food abundance for parrots also varied significantly between years, with greater food availability during the 1997 breeding season than that of 1996. The increased size and growth rates of nestlings in 1997 may have reflected this, and suggests the potential influence of environmental variability on parrot reproduction, particularly in such a markedly seasonal habitat.
Chapter
This is a book review by A. W. F. Edwards (published in Biometrics, 31(2) 229-230) of my books Biometry (by Sokal and Rohlf) and Statistical Tables (by Rohlf and Sokal) both published in 1981.
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