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An ecological and behavioral study of the Galapagos Penguin



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... An extremely influential factor on Galápagos penguin demography is the history of El Niño-Southern Oscillation (ENSO) events, which limit the upwelling and oceanic productivity around the islands and have shaped the breeding biology of this species [47]. Unlike other penguins, the Galapagos penguin only breeds when conditions are favorable and deserts eggs or young when upwelling fails [50]. The ENSO events have a long history, but the most recent recordings of severe bottlenecks affecting Galápagos penguins are those of 1982-83 and 1997-98, which may have reduced the population by approximately 77 and 65 percent, respectively [48,51,52,53]. ...
... Survival of populations depends in part on pathogen load and other characteristics of the species [26]. Although the Galápagos penguin is an opportunistic breeder that recovers its population size rather quickly after bottleneck events [49,50], the survival of the species will in part depend on whether the diversity at the MHC is sufficient to maintain the population in the face of potential diseases and parasites. While the alleles present may be adequate to counter the pathogens and parasites currently found in the Galápagos Islands, the species may easily become vulnerable to novel diseases. ...
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Although many studies have documented the effects of demographic bottlenecks on the genetic diversity of natural populations, there is conflicting evidence of the roles that genetic drift and selection may play in driving changes in genetic variation at adaptive loci. We analyzed genetic variation at microsatellite and mitochondrial loci in conjunction with an adaptive MHC class II locus in the Galápagos penguin (Spheniscus mendiculus), a species that has undergone serial demographic bottlenecks associated with El Niño events through its evolutionary history. We compared levels of variation in the Galápagos penguin to those of its congener, the Magellanic penguin (Spheniscus magellanicus), which has consistently maintained a large population size and thus was used as a non-bottlenecked control. The comparison of neutral and adaptive markers in these two demographically distinct species allowed assessment of the potential role of balancing selection in maintaining levels of MHC variation during bottleneck events. Our analysis suggests that the lack of genetic diversity at both neutral and adaptive loci in the Galápagos penguin likely resulted from its restricted range, relatively low abundance, and history of demographic bottlenecks. The Galápagos penguin revealed two MHC alleles, one mitochondrial haplotype, and six alleles across five microsatellite loci, which represents only a small fraction of the diversity detected in Magellanic penguins. Despite the decreased genetic diversity in the Galápagos penguin, results revealed signals of balancing selection at the MHC, which suggest that selection can mitigate some of the effects of genetic drift during bottleneck events. Although Galápagos penguin populations have persisted for a long time, increased frequency of El Niño events due to global climate change, as well as the low diversity exhibited at immunological loci, may put this species at further risk of extinction.
... The species faces several threats: introduced species such as cats Felis catus and rats Rattus spp. prey on chicks and eggs (Boersma 1977), and artisanal fishing causes mortality by entanglement (Crawford et al. 2017). Pollution (Jiménez-Uzcátegui et al. 2017), pathogens, and parasites put further pressure on its population (Merkel et al. 2007, Deem et al. 2010, Levin et al. 2013, Carrera et al. 2014. ...
... The maximum age of penguins tagged as chicks was calculated as the time elapsed in years since the bird was tagged until the latest recapture. The maximum age of penguins tagged as adults was calculated as the time elapsed in years from when the bird was tagged to the time of the latest recapture, plus two years to account for the transition time from juvenile to adult plumage (Boersma 1977). ...
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A maximum age of at least 17.7 years was recorded for a Galápagos Penguin Spheniscus mendiculus on Isabela Island during studies up until 2018. This individual was first captured as an adult of at least two years of age, as indicated by its plumage. In addition, we present records of other penguins, not quite as old, that were first captured as chicks. Longevity is affected by many different factors, making it useful in the design of conservation strategies.
... Since body feathers are more readily obtained from live animals, they provide an alternative to the use of wing feathers (Bearhop et al. 2000, Norris et al. 2007. Body feather moult in GAPEs, FLCOs, and WAALs occurs weeks before the onset of breeding and at an interval of about six months (Boersma 1976, Harris 1993b, Valle 1994. Therefore, the isotopic information from body feather tissue would be limited to the few months before the breeding season (Becker et al. 2007, Jaeger et al. 2009). ...
... Some of the advantages of using feathers for trophic research include the ability to gather long-term information (i.e., over a span of months) and the possibility of monitoring feeding behavior in pre-breeding stages (Cherel et al. 2000, Jaeger et al. 2009). Thus, the appropriate use of GAPE, FLCO, and WAAL body feathers is crucial, because these species retain these feathers for at least five months, then moult weeks before the breeding season (Harris 1973a, Boersma 1976, Valle 1994. Inaccuracies in isotopic niche estimates may be debated; however, we detected feeding-strategy patterns for all species that were consistent with those previously reported by groups using regurgitations from adult females to determine diet in different areas of the archipelago (Snow 1966, Fernández et al. 2001, Boersma et al. 2013). ...
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The Galápagos Penguin Spheniscus mendiculus, Flightless Cormorant Phalacrocorax harrisi, and Waved Albatross Phoebastria irrorata are endemic to Islas Galápagos. They are known to feed on different prey (including crustaceans, cephalopods, and/or several species of epipelagic and benthic fish), in accordance with different foraging strategies. In this work, we used stable-isotope analysis of carbon and nitrogen to corroborate available information on habitat use (δ ¹³ C) and trophic position (δ ¹⁵ N). Feather samples from the three species were collected in six different areas prior to the 2011 and 2012 breeding seasons. Results showed differences in foraging strategies between Galápagos Penguins and the other two species (δ ¹³ C and δ ¹⁵ N, P < 0.01). The Flightless Cormorant and Waved Albatross showed similar proportions of δ ¹³ C (P = 0.07), but they occupied different trophic levels (δ ¹⁵ N, P < 0.01). Isotopic signatures in Galápagos Penguins reflected differences based on their breeding areas (δ ¹³ C and δ ¹⁵ N, P < 0.01), which were subject to different environmental conditions. This information could be used to evaluate future ecological conditions among the feeding areas of these species.
... . For example, the Galápagos penguin (Spheniscus mendiculus) is the only penguin occurring naturally outside the Southern Hemisphere, endemic to the Galápagos Islands north of the equator36 . Assuming all else is equal, its phylogenetic endemism is expected to be higher at a continental scale north of the equator, but less likely in a global setting because its closest relatives comprise a group of about 20 species exclusive to the Southern Hemisphere. ...
... Mortality estimates for later age classes include an estimate of 18% based on return rates at PSJ from 2000-2010; for African penguins, 9% to 45% annual mortality from a variety of studies, including recent years during which the population has been in rapid decline (Randall 1983, La Cock & Hänel 1987, Whittington 2002, Kemper 2006, Ludynia et al. 2014, Sherley et al. 2014); for Magellanic penguins, 13% (Gownaris & Boersma 2019); and for Galápagos penguins, 11% (Boersma 1977). The 1998 PHVA used an estimate of 5% annual adult mortality as a baseline, but added to that 1%, 3%, or 5% mortality due to net entanglement. ...
Technical Report
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Humboldt penguin (Spheniscus humboldti) Population and Habitat Viability Assessment Workshop Final Report
... In addition to the effect of hatching asynchrony and egg size dimorphism on initial hierarchies, food provisioning may limit chick growth and survival (Taylor and Roberts 1962, Ainley and Schlatter 1972, Boersma 1976, Cooper 1977. In agreement with this, the size asymmetry between siblings of Magellanic penguins is an important determinant of which chick is fed, since the largest chick receives more food (Blanco et al. 1996). ...
Egg laying is one of the most important phases in a female bird's breeding cycle. Its cost is high because eggs contain all the resources needed for the development of an embryo. Variation in size and quality of eggs can have important long‐term consequences for offspring survival. Hatching asynchrony is known to influence sibling competition in many bird species. Last‐hatched chicks will have a competitive disadvantage throughout the pre‐fledgling period because they are smaller. The aim of this study was to analyze the effect of hatching asynchrony and egg size variation on the growth and fledging success of Magellanic penguin Spheniscus magellanicus chicks after disentangling the effects of parental condition. We simultaneously manipulated egg size dimorphism, hatching asynchrony and parental condition by performing a cross‐fostering experiment, creating broods with controlled egg size dimorphism and hatching asynchrony in a colony of Magellanic penguins located in Isla Quiroga, Santa Cruz, Argentina. We found that hatching asynchrony had a negative effect on last‐hatched chicks, but this disadvantage was mitigated by egg size dimorphism in their favor. Moreover, females in good condition invest more in second than in first chicks, which, added to a greater investment by foster fathers, leading to offspring fledging in good condition. On the contrary, for the first‐hatched chicks, we found that body condition of the biological father was an important factor for their growth. We conclude that raising more than one chick seems to be a decision based on parental condition throughout the breeding season.
... Additionally, previous studies of common murres have shown that lower prey availability is as sociated with lower nest co-attendance and fledging success (Uttley et al. 1994, Zador & Piatt 1999. Al though previous seabird studies have demonstrated relationships between nest abandonment and body condition (Boersma 1976, Yorio & Boersma 1994, adult body condition did not appear to differ be tween colonies. Body condition measurements, however, were taken during late-incubation and chick-rearing and thus do not represent the incubation period when most nests on Funk Island failed. ...
Spatial patterns of breeding seabirds are influenced by the distribution of resources in relation to the colony and the density of conspecifics from the same or adjacent colonies. We conducted an inter-colony comparison of foraging space use and behavior, diet, and reproductive success of common murres Uria aalge breeding at a large offshore and a small inshore colony on the northeastern coast of Newfoundland (Canada) during 2016−2018 under varying prey (capelin Mallotus villosus) biomass. Murres from the large offshore colony foraged over a greater area, with greater individual foraging distances, indicative of higher commuting costs compared to the smaller inshore colony. Although this pattern might reflect prey depletion near the offshore colony due to higher conspecific densities, it likely also reflects the greater distance to predictable, high-abundance prey aggregations. This is supported by high spatial overlap of foraging areas from both colonies near coastal, annually persistent capelin spawning sites. Adult diet was similar be tween colonies during incubation, but diverged during chick-rearing, with offshore murres consuming a higher proportion of alternative prey, while inshore murres consumed more capelin. These differences did not affect fledging success, although hatching success was lower in the larger colony, suggesting that divergent factors (e.g. predation, nest attendance) influence colonyspecific population dynamics. Overall, our findings suggest that abundant local prey is key in shaping spatial patterns of breeding common murres in northeastern Newfoundland and results in apparently minimal intraspecific competition. As anthropogenic pressures on resource availability heighten, insight into factors influencing intraspecific foraging niche dynamics will be critical to inform management.
... La incubación es compartida por ambos padres al igual que el empollamiento, la cual es una estrategia para minimizar el costo de energía en la reproducción (Boersma 1976 La anidación se presenta casi todo el año con algunos picos marcados, los cuales pueden estar relacionados a cambios en la disponibilidad del alimento (Duffy 1990 Es sabido que el éxito reproductivo puede estar afectado ya sea por el lugar en donde se encuentre el nido dentro de la colonia y por las características que el nido presente (Gandini et al. 1997;Zavalaga & Paredes 1997). De esta manera el nido tipo "madriguera" se ha reportado como uno de los de mayor efectividad en la reproducción, sobre todo a diferencia de los nidos superficiales. ...
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Se ha estudiado los aspectos reproductivos de Spheniscus humboldti en la Isla Pachacamac, Lima (12°18’04.39” S76°54’11.60”O) durante el año 2010. El estudio se basó en la caracterización de la colonia mediante la descripción de las características de los nidos y localización del grupo en la colonia principal de la Isla Pachacamac, denominada el “Embudo”, además se realizaron observaciones del comportamiento reproductivo, así se empleó el método de registros de nidos y presupuestos de tiempo. Los mayores picos reproductivos (puesta) se presentaron en el mes de Abril y Agosto; siendo la segunda temporada reproductiva, de Agosto a Noviembre, la más exitosa respecto a la obtención de volantones. El éxito de incubación fue de 0.45 huevos eclosionados por huevo puesto; el éxito de crianza, 0.58 volantones por huevo eclosionado; y el éxito de anidación 0.47 volantones por nido. El éxito reproductivo de la colonia está influenciado por la cantidad de plumas presente en el nido y la localización del grupo dentro de la colonia, no siendo afectado éste por el tipo de nido (superficial, escarpado y madriguera). Se registraron 46 comportamientos, 27 fueron reproductivos. Se encontró diferencias significativas entre los siete meses de estudio en todos los comportamientos. Los comportamientos sexuales-sociales, agresivos, de construcción del nido y locomoción presentaron diferencias significativas con respecto al sitio de asentamiento. Se concluyó que el comportamiento reproductivo es afectado por el lugar donde se desarrolla la colonia.
... Patterns of phylogenetic endemism tend to manifest at large global extents, but phylogenetic endemism can be severely influenced in a continental or country setting 31,41 . For example, the Galápagos penguin (Spheniscus mendiculus) is the only penguin occurring naturally outside the Southern Hemisphere, endemic to the Galápagos Islands north of the equator 42 . Assuming all else is equal, its phylogenetic endemism is expected to be higher at a continental extent north of the equator, but lower in a global setting because its closest relatives comprise a group of about 20 species exclusive to the Southern Hemisphere. ...
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Areas of endemism are important in biogeography because they capture facets of biodiversity not represented elsewhere. However, the scales at which they are relevant to research and conservation are poorly analysed. Here, we calculate weighted endemism (WE) and phylogenetic endemism (PE) separately for all birds and amphibians across the globe. We show that scale dependence is widespread for both indices and manifests across grain sizes, spatial extents and taxonomic treatments. Variations in taxonomic opinions—whether species are treated by systematic ‘lumping’ or ‘splitting’—can profoundly affect the allocation of WE hotspots. Global patterns of PE can provide insights into complex evolutionary processes but this congruence is lost at the continental to country extents. These findings are explained by environmental heterogeneity at coarser grains, and to a far lesser extent at finer resolutions. Regardless of scale, we find widespread deficits of protection for endemism hotspots. Our study presents a framework for assessing areas for conservation that are robust to assumptions on taxonomy, spatial grain and extent.
... Both Galapagos Penguins (Spheniscus mendiculus) and Magellanic Penguins (S. magellanicus) usually lay longer first eggs and wider second eggs (Boersma 1976). Although they differ in linear dimensions, Magellanic Penguin eggs are typically similar in volume ). ...
We investigated patterns and consequences of intraclutch egg-size variation in Magellanic Penguins (Spheniscus magellanicus). First-laid eggs were significantly larger than second-laid eggs, although the mean difference represented only 2% of an average egg's volume. The degree of intraclutch egg-size variation was similar among years and females of different ages. Intraclutch egg-size variation did not affect intraclutch differences in chick hatching weights or fledging success. We found no selective advantage for laying eggs of different sizes. Because both eggs have an equal probability of being lost, chance favors equal provisioning of eggs. Egg volume explained 35% of the variation in hatching weight but did not determine fledging success. Laying order, year, and female age were better predictors of fledging success than egg size. Factors such as laying and hatching order, parental quality, oceanographic conditions, fights, and predation are more important in determining chick survival than are differences in egg size.
The suggestion that the annual cycle of plant production in tropical oceanic regions may be negligible or non-existent is examined, using data from a year-long cruise series in the eastern tropical Pacific. Results of analysis of variance show a highly significant seasonal effect. Average values of the seasonal cycle were found to range from 127 to 318 mg C/m2/day, a systematic two-fold variation over the year. Annual production was 75 g C/m2/year. Significant differences also were found between longitudes, and a slightly significant interaction occurred between season and longitude. Probable sources of the seasonal cycle include time variation of thermocline topography and variation of nutrient supply from local source areas such as the Costa Rica Dome, Gulf of Tehuantepec, Peru Current extension, and Equatorial Undercurrent domain.
The comfort movements of Anatidae are described in detail on the basis of observations on 114 species including representatives of all tribes except the Torrent Ducks (Merganetta). A fundamental distinction is made between the occurrence of comfort movements in (1) basic situations (where they are apparently serving their original functions, mostly in caring for the body surface) and (2) secondary situations (where the movements appear irrelevant and unlikely to be serving their original functions). Under ''basic situations'', the form of each movement in the Mallard is described, and attention is drawn to variations occurring in other species. Note is made of the situations in which the comfort movement is performed, and its probable function is discussed. Under ''secondary situations'', an attempt is made to distinguish between instances in which the movement is serving as a social signal and those in which it is not. Comfort movements are classified into seven broad categories : shaking movements, stretching movements, cleaning movements, oiling preening, nibbling preening, washing, and bathing. Most of the nine shaking movements probably function to remove water or foreign material from various parts of the body. The frequency of wing-flapping in White-fronted Geese increases in response to rain and dense fog. Vigorous wing-shaking occurs during oiling and it may have a special function in relation to this activity. Wing-shuffling and tail-fanning are performed after bathing and probably help to dry the feathers. There are three stretching movements: wing-and-leg-stretch, both-wings-stretch, and jaw-stretch. They are all associated with periods of rest; the wing stretches occur during preening before sleeping as well as after awakening. Scratching is by the ''direct'' method, and appears to be elicited by an irritation on the head. An ''extended'' type of scratching is associated with bathing, and probably helps to clean the plumage. Scratching is thought to play no part in the distribution of oil to the head plumage. A movement which is probably scratching occurs frequently during flight in the Green-winged Teal; this is the only instance of an aerial comfort movement which has been seen repeatedly in any species of waterfowl. Oiling follows bathing, but it also occurs at other times. Only the most aquatic groups (e.g. Aythya, Bucephala, Oxyura) oil frequently while swimming. Many oiling preens last only for a few minutes; others merge into nibbling preening which may continue for about 30 minutes. In several species at least, oiling is not performed on the nest during the incubation period, but it occurs repeatedly when hatching begins. This behaviour is released by stimuli from the ducklings, and it apparently serves to distribute oil to the ducklings. Occasional nibbling preening movements are probably responses to irritations on the body surface. The causation of nibbling with bill-dipping is uncertain; it may help to clean the plumage or skin. Social preening occurs in a number of tropical waterfowl; it is especially developed in several species of Dendrocygna. It probably supplements scratching as a method of grooming the head feathers. Three bathing movements are distinguished - head-dipping, somersaulting, and wing-thrashing. Dashing-and-diving consists of escape patterns which have come to be closely associated with high intensity bathing. Mallard ducklings perform most comfort movements within the first few days of life. High intensity bathing movements (somersaulting, wing-thrashing, dashing-and-diving) were not seen until the ducklings were 13-14 days old. Almost all comfort movements are of universal occurrence in basic situations in the family. The few specific variations represent adaptations to different ways of life, and are of very limited use as indicators of taxonomic relationships. The causation of comfort movements in basic situations is discussed, but no firm conclusions can be drawn in the absence of experimental evidence. Bathing, shaking, wing-flapping, and a few other comfort movements occur after alighting, after a disturbance, after copulation, and after hostile encounters. These are considered as secondary situations; the comfort movements are thought to be caused, at least partly, by the social tendencies which have been strongly activated. Preening movements occur before changing position on the nest during incubation. Some of these may be responses to irritation. Some function in loosening down from the breast. Many comfort movements occur before flight. Some are repeated with a high frequency and are thought to function as social signals indicating intention to fly, e.g. Head-shaking in many tribes, bathing in certain Mergini. Comfort movements have provided an important source of male pre-copulatory signals, especially in the Mergini. Some have a ritualized form, but most are very similar to the normal comfort movements. Within the Mergini, there are many specific variations in the displays which occur and in the way they are combined in sequences. These displays provide useful taxonomic characters in the tribe. The Swimming-shake (in courting parties) and Preen-behind-wing are widely distributed displays in the duck tribes. There is much variation in their frequency and importance from species to species. Five ritualized Preening movements are distinguished. A correlation between preening displays and conspicuous plumage patterns is not always apparent. Both ritualized and unritualized comfort movements are commonly associated with pair-formation activities and hostile encounters. Displays may have evolved from both ''irrelevant'' and ''relevant'' comfort movements. There is much evidence of the presence of conflicts between antagonistic tendencies in the situations in question (e.g. before flight, before copulation, during pair-formation). Some ritualized comfort movements (shakes, bathing, preening movements) occur in situations where normal counterparts would be expected. Certain nibbling preening movements and several shaking movements occur as displays in many species, but ritualized oiling actions are rare. Some comfort movements (e.g. bill-cleaning, wing-and-leg-stretch, shoulder-rubbing) are used by only a few species. The high intensity bathing movements (wing-thrashing and somersaulting) are not known to occur as displays.
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