We report results of a 4-year translocation effort to reestablish a breeding population of Evermann’s Rock Ptarmigan (Lagopus muta evermanni) in the Near Islands group of the western Aleutian Archipelago. Habitat restoration was completed by eradication of introduced foxes from Agattu Island by 1979. We captured and moved 75 ptarmigan from Attu Island to Agattu Island during 2003–2006, nd monitored 29 radio-marked females in the last 2 years of the study. We compared the demography of newly translocated birds (n 5 13) with resident birds established from translocations in previous years (n 5 16). Mortality risk was increased by translocation and 15% of females died within 2 weeks of release at Agattu Island. All surviving females attempted to nest but initiated clutches 8 days later in the breeding season and laid 1.5 fewer eggs per clutch than resident females. Probability of nest survival (x¯ 6 SE) was good for both translocated (0.72 6 0.17) and resident females (0.50 6 0.16), and renests were rare. Probability of brood survival was higher among translocated (0.85 6 0.14) than resident females (0.25 6 0.12), partly as a result of inclement weather in 2006. Fecundity, estimated as female fledglings per breeding female, was relatively low for both translocated (0.9 6 0.3)and resident females (0.3 6 0.2). No mortalities occurred among radio-marked female ptarmigan during the 10-week breeding season, and the probability of annual survival for females in 2005–2006 was between 0.38 and 0.75. Translocations were successful because females survived, successfully nested, and recruited offspring during the establishment stage. Post-release monitoring provided useful demographic data in this study and should be a key component of translocation programs for wildlife restoration. Future population surveys and additional translocations may be required to ensure long-term viability of the reintroduced population of ptarmigan at Agattu Island.
The Atlantic Forest in eastern South America harbors 849 bird species, of which 216 are endemic and 122
threatened with extinction. It is also one of the 25 biodiversity hotspots recognized throughout the world. Within this biome,
the Serra do Mar stands out as an important area of endemism in South America. Nonetheless, ornithological knowledge of
the Serra do Mar remains underestimated and incomplete. One lacunae of information for the Serra is a region called
Curucutu, which is adjacent to the largest urban area in South America. The avifauna of Curucutu has been sampled
occasionally since 1900, but all of the available data have yet to be published. Therefore, we compiled ornithological data
published on Serra do Mar over the last 118 years and undertook a 16-year-long field inventory using 3 methods of data
collection simultaneously (visual observations, point counts, and mist nets) for a total of 395 field days. Sampling was
performed in forest and natural grasslands along an elevational gradient from 5 to 850 m.a.s.l. A total of 422 species of birds,
128 of which are endemic to the Atlantic Forest and 29 that are threatened with extinction, were documented, thereby
illustrating the importance of this region. Of this total, 382 species occur in Nucleo Curucutu do Parque Estadual da Serra do ´
Mar, demonstrating the importance of this reserve to the regional avifauna. We made several significant additions to the
avifauna of the region, with only one species, the Black-necked Aracari (Pteroglossus aracari), being considered regionally
extinct because of a lack of records since 1900—thus representing a kind of poorly studied extinction that has yet to be
investigated and may be happening with much greater frequency in large forested areas of Serra do Mar. Even though the
region is partially protected, being a state reserve, its proximity to the largest urban area in South America automatically puts
the area under threat, especially considering the disorganized urban growth that has been encroaching upon natural areas of
the region. The expansion of current reserves, and the establishment of new protected areas in this region of Serra do Mar is
essential for guaranteeing the integrity of this very rich and threatened bird community of the Atlantic Forest.
A Leach's Storm-Petrel (Oceanodroma leucorhoa) initially banded on Tenerife, Canary Islands, Spain in October 1995 was recaptured on Bon Portage Island off the south tip of Nova Scotia, Canada in August 2009, 13 years and 10 months later, and some 4,660 km and 51° longitude away. Recoveries on breeding areas of seabirds that were originally banded on wintering areas are exceedingly rare. This record appears to constitute the first winter-summer recapture of a Leach's Storm-Petrel.
The process of urbanization and its effects on birds has rarely been documented over long time periods. One exception is a bird count started in the 1860s, when the American ornithologist William Brewster first recorded all the bird species on his property in Cambridge, Massachusetts. Since then, invasive species such as the House Sparrow (Passer domesticus) have been introduced, and the site transformed from an estate surrounded by farmland on the rural edge of the city to a residential neighborhood in the inner core of the Boston metropolitan area. We are fortunate to have additional bird species accounts from around 1900, 1940, 1950, and 1960. In 2012 we repeated the bird survey, thus expanding the time series to 150 years. The changes in the bird community over time have been profound and the data contain a wealth of “stories” about how different species and species guilds have coped. The transition from an agricultural to an urban but also more forested system is clearly visible in the records. Overall, species richness has declined from 26 species in the 1860s to just 12 in 2012. However, this is a slight increase from the low point in the 1960s, and there is evidence that some conditions for birds have improved in the last 50 years.
Surprisingly little is known about the basic biology of many large raptor species. Zoos and wildlife rehabilitation centers can help remedy this knowledge gap by providing a wealth of data on species whose in situ counterparts are difficult to study. We present one such example here by recording multiple new longevity records for the Barred Owl (Strix varia Barton, 1799). At 34 years and 1 month of age, the longest-lived new record surpasses the previous oldest known individual by a decade. Along with the additional new and already available longevity data we reviewed, the information provided here will prove useful for those working on many aspects of owl biology.
Nearctic-neotropical passerines may spend up to one-third of the year in migration. Stopover sites have a critical role in providing migrant passerines with areas to rest and replenish fat stores. We characterized the stopover ecology of the Tennessee Warbler (Oreothlypis peregrina) at an inland site in Vicksburg, Michigan, using data from 4,607 warblers captured between 1990 and 2007. The recapture rate ranged from 1.6 to 12.1% annually and recaptured migrants averaged small but significant mass gains. Estimates of mass change using regression of mass on time of capture also suggested mass increases at this site. Recapture rate and mass gain estimated by regression varied significantly across the 18 years of study, although stopover length and mass change among recaptured individuals did not. Adult (after hatching year, AHY) warblers in active flight feather molt had an average lower mass and were four times more likely to be recaptured than non-molting adults. Over 95% of birds captured were hatching year (HY). The average condition and mass gains estimated by regression of HY warblers were lower than that of AHYs, but recapture rate, stopover length, and mass gains by recaptured individuals did not differ between the two age groups. The high number of captures and mass gains demonstrate the value of this site for fall migrant Tennessee Warblers. The annual differences in recapture rate and mass gains reported in this study suggest that several years of data may be needed to develop an accurate assessment of the typical use of a stopover site by migrants.
The American Barn Owl (Tyto furcata) is a bird of prey that predominantly feeds on small mammals by swallowing them whole; the undigested parts are regurgitated in pellets. This study aimed to characterize the diet of the American Barn Owl in a lowland Atlantic Forest remnant in southeastern Brazil by analyzing the material contained in pellets. Prey items were quantified by counting the number of skulls or paired bones in each pellet, and the ages of the mammals (rodents) found as prey were classified based on the pattern of wear of the occlusal surface of the molars. For invertebrates, we counted the number of heads or hind legs. We analyzed 48 pellets and each one contained 1-7 depredated individuals (mean= 4.0). Two major groups of food items were identified (192 specimens in total): mammals (Mus musculus [n=179 specimens, or 93.2% of prey items; FO = 100%], Rattus rattus [n = 2, or 1.0%; FO= 4.2%], and Carollia sp. [n = 1, or 0.5%; FO= 2.1%]) and insects (n=8 samples; FO=16.7%: Orthoptera [n=6 specimens, or 3.1%; FO=12.5%], Lepidoptera [n=2, or 1.0%; FO=4.2%], and Hymenoptera [n=2, or 1.0%, FO=4.2%]). For the exotic rodent M. musculus, 142 right mandibular branches were identified, of which 8.5% were classified as Pup (n = 12 individuals), 57.0% as Adult I (n = 81), 19.0% as Adult II (n = 27), and 15.5% as Senior (n = 22). The results corroborate similarities in the diet and feeding behavior of T. furcata throughout its distribution in the Americas and with T. alba. Tyto furcata, although generally a rodent specialist, has an opportunistic foraging strategy and may respond to prey availability, possibly acting as a natural biological control agent of agricultural pests such as exotic rodents. Further studies are recommended to assess whether seasonality influences the frequency at which nonnative prey are consumed by T. furcata.
The extinct Laysan Rail or Crake (Zapornia palmeri) was a small, flightless rail endemic to Laysan Island in the northwestern chain of the Hawaiian Archipelago. I detail the collections made, including eggs, nests, juveniles, and numerous adults prior to its extinction. The juvenile plumage was seemingly well documented, but my study of a series of juvenile specimens collected in 1891 and 1896 provides hitherto undescribed molt changes, from downy chick to definitive plumage. Morphometric data show that sexual size dimorphism is present with males being slightly more robust in bill, legs, and feet. I provide a detailed review of the literature showing the chronology of events that led to the extinction of the species and how this easily could have been avoided.
Efforts to protect the endangered northwest Atlantic population of Roseate Tern (Sterna dougallii) have typically focused on a small number of breeding colonies distributed from Nova Scotia to New York. Yet the species is also potentially vulnerable at staging sites used by adults and recently fledged juveniles preparing for their southward migration to South America. My study found no evidence of pronounced changes in the overall distribution of Roseate Tern fall staging flocks over 5 decades. Coastal Massachusetts, especially Cape Cod, Nantucket, and Martha's Vineyard, annually support large numbers, representing a significant portion of the North Atlantic breeding population, from mid-July through late August. This work provides a long-term review of Roseate Tern fall staging behavior in northeastern North America and a foundation for ongoing and future studies aimed at clarifying specific threats faced by this species at specific staging sites during the post-breeding period.
Global change can affect several aspects of bird biology, including population size and migration timing. We used count data collected during 25 years (1990-2014) at Hawk Mountain Sanctuary, a raptor migration watch-site in eastern Pennsylvania, to investigate population changes in Ruby-throated Hummingbirds (Archilochus colubris) and the timing of their autumn migration, in light of ongoing climate change. Hummingbird numbers increased significantly from 1990-2014. The first 5%-, 50%-, 95%- and average passage dates of hummingbirds over this time indicated an earlier passage, with the first 5% passage-date shifting earlier significantly. Passage duration (number of days between 5% and 95% of the flight) remained relatively constant from 1990-2014. In light of similar shifts in timing of spring passage of this species, our results suggest that Ruby-throated Hummingbirds may be shifting the timing of their migratory cycle.
This study presents breeding phenology, fledgling production, and nest success for the Black Swift (Cypseloides niger) over a 22 year period at the Box Canyon colony, Ouray, Colorado, USA. Data were collected annually from 1996 to 2017 by direct observation from arrival of the birds at the nesting colony until all adults and fledglings departed. We documented dates of first arrival, laying, incubation onset, hatching, and fledging, and determined the intervals from arrival to laying, laying to incubation, length of incubation, and length of the nestling period in each year. Breeding events followed each other closely and showed little chronological change throughout the study. We identified a negative trend in the number of nest attempts and fledged Black Swift chicks over time but found no relationship between these 2 trends and the environmental factors of summer temperature, summer precipitation, or tourist visitation. The Mayfield estimate of nest success for all nest attempts was 77.5%. There was unexplained annual variation in nest success, but the trend in nest success remained static, with no correlation between nest success and temperature, precipitation, or tourist visitation. This study represents the largest dataset and longest-duration investigation into the breeding phenology and nest success of the Black Swift.
Mercury (Hg) is a naturally occurring widespread and persistent contaminant globally, and its organic form is highly toxic to living organisms and is known to impact humans and wildlife. Our primary goal was to use feathers to establish a contemporary baseline of total Hg contamination levels in Peregrine Falcons (Falco peregrinus) that occur on the outer coast of Washington. We document concentrations of total Hg in feathers of 151 peregrines primarily captured on beaches from 2001 to 2016. Peregrines were captured throughout the year, with breeding and natal areas of most individuals undetermined. The bulk of our samples consisted of fourth secondary (s4) feathers, but we include fourth primary and undertail covert feathers for comparison. All s4 feather samples contained detectable concentrations of total Hg (range = 0.7–69.83 µg/g), with mean concentrations in hatch-year (HY) feathers (mean = 6.05 µg/g) significantly lower than in second-year (mean = 22.55 pg/g) and after-second-year (mean = 24.48 µg/g) feathers. We captured 23 individuals more than once to track total Hg concentrations over time (up to 12 years between first and last capture), detecting an increasing trend through their third year before stabilizing in subsequent years. All individuals first captured while in HY plumage and later recaptured (n = 20) exhibited an increased concentration of total Hg in later years (mean maximum difference over time = 25.39 µg/g). Our 16-year study illustrates widespread contamination of total Hg in peregrines captured in coastal Washington, with evidence of bioaccumulation within individuals and between age classes. Encouragingly, peregrines in HY plumage sampled during the final third of our study period exhibited a significantly lower mean total Hg concentration than the first two-thirds of our study. We detected greater total Hg concentrations in coastal Washington peregrines than in nearly all known published studies involving peregrines of various subspecies in North America and Europe, although additional research is needed to establish toxic effects levels in this species.
Howell et al. (2003) proposed modifications to the system of molt terminology for birds developed by Humphrey and Parkes (1959) to address a perceived inconsistency in the Humphrey-Parkes ('H-P') system that Howell et al. (2003) termed the 'first basic problem'. These modifications have been adopted by mainstream ornithological literature, but are premature and unnecessary. The recharacterization of the prejuvenal and first prebasic molts, and resulting plumages, by Howell et al. (2003) is: (1) not supported by scientific studies, (2) inconsistent with several factors that support classification of these molts and plumages under the H-P system, and (3) contrary to the fundamental purpose of that system. Moreover, the H-P system can be interpreted in a manner that resolves the 'first basic problem' without recharacterizing the prejuvenal and first prebasic molts and resulting plumages. The H-P system also can be interpreted to start the first molt cycle with commencement of the initial acquisition of contour feathers and provide a fixed point to start a nomenclature of molts and plumages. The four molt strategies identified by Howell et al. (2003) may be explained by variability in conventional first prebasic and first prealternate molts and are not dependent on adoption of their proposed modifications of the H-P system. Ornithologists are encouraged to re-examine the modifications to the H-P system proposed by Howell et al. (2003) and to resolve existing conflicts in North American molt terminology by adopting the proposed interpretations of the H-P system identified in this paper.
We monitored 256 Peregrine Falcon (Falco perigrinus) nest-sites, accumulating 852 site-years in Colorado, Wyoming, and Montana during 2005-2009. The sites included 42 selected by the U.S. Fish and Wildlife Service for its monitoring program in 2006 and 2009. Annual nest occupancy rates ranged from 75 to 100% and varied as much as 10% among years in each state, and 25% among states. Nest success was 77% overall (n = 687), but differed as much as 25% among states in 2009. Reproduction rate was 1.8 young/pair for 687 nesting attempts where outcome was known, and annual state averages ranged from 1.2 to 2.2 young/pair. We discovered or were alerted to 77 pairs at new locations, suggesting that future searches will be successful. Overall, 353 nesting locations in the three states combined had been recorded at the end of the 2009. Wide variations among years in occupancy, nest success, and reproduction underscore the necessity of long-term monitoring of Peregrine Falcons on a regional, rather than a state, perspective.
In a recent publication, Wisenden et al. (2020) examined responses of territorial male Red-winged Blackbirds (Agelaius phoeniceus) to models constructed with ultraviolet (UV)-reflective red epaulets for the purpose of determining if the addition of UV reflectance to epaulets ("UV+") changed the effectiveness of signals to receivers relative to "control" epaulets under field conditions. The authors hypothesized that "UV+epaulet coloration represents a visual signal with increased efficacy in territorial interactions." They presented behavioral data but no visual modeling data. Our aims in this commentary are to suggest alternative terms to those used by the authors, to express concern about the use of sunscreen to manipulate the UV condition of surfaces, and to make a plea for additional data collection in future studies of avian visual ecology. The terms UV+ and UV- should be reserved for studies that create environments free from UV radiation for comparison with environments that include UV radiation. We believe that commercial sunscreens are not an appropriate choice for altering the UV conditions of surfaces presented during behavioral trials because they potentially introduce confounding influences from other sensory inputs or irritation of peripheral nerves. Wisenden et al. altered the UV absorbance of their sunscreen-treated models but did not present absorbance spectra and may not have collected those data. We acknowledge that the lack of absorbance spectra is not unusual. We implore any such future studies to collect absorbance spectra of treated and control surfaces so that those data may be used to improve visual models for UV-sensitive animals. Los ec´ologos visuales de aves deben considerer la absorbencia UV y todas las modalidades sensoriales: respuesta a Wisenden et al. (2020) RESUMEN (Spanish)—En una publicaci´on reciente, Wisenden et al. (2020) examinaron las respuestas de machos territoriales del tordo Agelaius phoeniceus a modelos construidos con charreteras rojas reflejantes ultravioletas (UV) con el prop´osito de determinar si la adici´on de reflectancia a las charreteras (‘‘UVþ’’) cambiaba la efectividad de las se˜nales dirigidas a receptores en relaci´on con charreteras ‘‘control’’ bajo condiciones de campo. Los autores ten´ıan la hip´otesis de que ‘‘la coloraci´on UVþde las charreteras representa una se˜nal visual con eficacia aumentada en interacciones territoriales’’. Los autores presentaron datos conductuales pero no datos de modelado visual. Nuestra meta en este comentario es sugerir t´erminos alternativos a aquellos empleados por los autores, expresar preocupaci´on por el uso de bloqueador solar para manipular la condici´on UV de superficies y hacer un llamado para la colecta de datos adicionales en futuros estudios de ecolog´ıa visual aviar. Los t´erminos UVþy UV– deben estar reservados para comparaciones con ambientes que incluyan radiaci´on UV. Pensamos que el uso de bloqueadores solares comerciales no es una elecci´on adecuada para la alteraci´on de las condiciones UV de superficies durante pruebas de comportamiento porque podr´ıan introducir influencias confusas provenientes de otras se˜nales sensoriales o irritar nervios perif´ericos. Wisenden et al. alteraron la absorbencia UV de sus modelos tratados con bloqueador solar pero no presentaron espectros de absorbencia y podr´ıan no haber colectado esos datos. Reconocemos que la carencia de espectros de absorbencia no es inusual. Pedimos que cualquier estudio futuro colecte espectros de absorbencia en superficies tratadas y controles para que esos datos puedan ser usados para mejorar los modelos visuales de animales sensibles a UV.
Between 26 and 28 June 2021, the United States' Pacific Northwest endured an unprecedented heatwave that broke previous temperature records by 5 C. Here, we report the impacts of the heatwave on Bushtit (Psaltriparus minimus) nests being monitored as part of a long-term study in Portland, Oregon. Of the 8 nests active during the event, nestling mortality was 100% in 3 nests and 4 broods survived at least in part. We suspect the excessive heat forced at least one additional brood to fledge early. Remains of nestlings found in 2 nests that eventually fledged suggest that even those encountered brood reduction during the heatwave. Nests with broods that survived were closer to a water source (x̄=13 m) than nests with broods that did not survive (x̄ = 148 m). In addition, surviving broods were younger (either eggs or <4 d of age) than those that perished (>9 d of age). Since these are only the second incidence of total nestling mortality other than depredation observed during Sloane's long-term research on Bushtits in Oregon and Arizona (1986present), we consider this to be a significant finding and indicative of the future negative effects of global climate change on temperate zone species of breeding passerines.
We report an observation of a juvenile Rough-legged Hawk (Buteo lagopus) on the north slope of Pico de Orizaba, the highest mountain in Mexico. To our knowledge, this is the southernmost record of the species. Furthermore, our observation is possibly the highest recorded elevation for the species.
Grebes are unique among birds in ingesting their own feathers. This behavior and the subsequent ejection of feathers as pellets have long puzzled ornithologists, who have tended to treat feather-eating and pellet-casting as independent behaviors rather than as complementary components of the digestive process. The diet of many grebes, including those with the most ancestral traits, is dominated by small invertebrates whose exoskeletons are resistant to digestion. Most birds eat grit to mechanically break down hard foods. Not so with grebes, which are chemical digesters. Feather-eating performs two main functions. The first is to retain food until it is fully digested; this is accomplished by a large feather bolus in the gizzard. The second, provided by a distinct group of feathers in the pyloric pouch, is to filter undigested or indigestible items from entering the intestine. Some of the gizzard bolus is probably regurgitated nightly, but the process is incomplete and undigested food can persist in the gizzard overnight and indigestible hard parts for several months. The pyloric plug is expelled irregularly. Inasmuch as feathers and other debris must eventually be discarded, pellet-casting is an inevitable consequence, not cause, of feather-eating. I propose that grebes originated as surface feeders and adopted feather-eating to enhance the efficiency of feeding on small arthropods or other hard-bodied taxa that are difficult to digest. This interpretation is relevant to understand the early evolution of grebes.
The Brown Dipper (Cinclus pallasi) was discovered to be a regular winter resident in the mountains of Verkhoyansk Range in Northeastern Siberia. This area is one of the coldest in the Northern Hemisphere, with winter temperatures normally staying around -50°C and occasionally dropping below -65°C. Despite the extreme cold, the birds exhibited normal foraging behavior. Precise breeding locations of these dippers, wintering almost 200 km NW from the species' known range, remain unknown.