Physical condition and stress levels during early development reflect feeding rates and predict pre- and post-fledging survival in a nearshore seabird

Lamb, Juliet S.; O’Reilly, Kathleen; Jodice, Patrick G. R.

doi:10.1093/conphys/cow060

Cited by 17 publications

(15 citation statements)

References 69 publications

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“…We did not find a significant relationship between colony size and either of the nestling condition metrics we tested (body condition or feather corticosterone). We have previously determined that both feather corticosterone and body condition are effective predictors of chick survival in this system (Lamb et al., ), so we can extrapolate from our results that the reproductive rates of pelicans do not decline with colony size. This result contradicts several previous studies suggesting a relationship between chick condition and colony size (e.g., Cairns, ; Gaston et al., ; Hunt et al., ); however, several other studies have failed to find a correlation (Ainley et al., ; Brown & Brown, ; Gaston et al., ).…”

Section: Discussionsupporting

confidence: 56%

“…Briefly, we removed the feather rachis, cut each feather into small (<0.5 mm) segments, extracted corticosterone in three successive methanol washes, reconstituted samples in buffer, and measured corticosterone concentrations via radioimmunoassay (MP Biomedicals, California, USA). Complete details of corticosterone analysis are described in Lamb, O'Reilly, and Jodice ().…”

Section: Methodsmentioning

confidence: 99%

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Influence of density‐dependent competition on foraging and migratory behavior of a subtropical colonial seabird

Lamb

Satgé

Jodice

2017

Ecology and Evolution

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Density‐dependent competition for food resources influences both foraging ecology and reproduction in a variety of animals. The relationship between colony size, local prey depletion, and reproductive output in colonial central‐place foragers has been extensively studied in seabirds; however, most studies have focused on effects of intraspecific competition during the breeding season, while little is known about whether density‐dependent resource depletion influences individual migratory behavior outside the breeding season. Using breeding colony size as a surrogate for intraspecific resource competition, we tested for effects of colony size on breeding home range, nestling health, and migratory patterns of a nearshore colonial seabird, the brown pelican (Pelecanus occidentalis), originating from seven breeding colonies of varying sizes in the subtropical northern Gulf of Mexico. We found evidence for density‐dependent effects on foraging behavior during the breeding season, as individual foraging areas increased linearly with the number of breeding pairs per colony. Contrary to our predictions, however, nestlings from more numerous colonies with larger foraging ranges did not experience either decreased condition or increased stress. During nonbreeding, individuals from larger colonies were more likely to migrate, and traveled longer distances, than individuals from smaller colonies, indicating that the influence of density‐dependent effects on distribution persists into the nonbreeding period. We also found significant effects of individual physical condition, particularly body size, on migratory behavior, which in combination with colony size suggesting that dominant individuals remain closer to breeding sites during winter. We conclude that density‐dependent competition may be an important driver of both the extent of foraging ranges and the degree of migration exhibited by brown pelicans. However, the effects of density‐dependent competition on breeding success and population regulation remain uncertain in this system.

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Section: Discussionsupporting

confidence: 56%

Section: Methodsmentioning

confidence: 99%

Influence of density‐dependent competition on foraging and migratory behavior of a subtropical colonial seabird

Lamb

Satgé

Jodice

2017

Ecology and Evolution

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“…After this point, nestlings become flight-capable and may leave the breeding colony (Shields 2014), and although adults may continue to visit the colony, they generally cease to feed nestlings after 60 days of age (Montgomery and Martínez 1984). Our own observations indicate that mortality of nestlings older than 8 weeks is extremely rare, making 60 days an appropriate cutoff for determining that a nest has successfully fledged young (Lamb 2016). For pelicans that re-nested following capture, we interpreted the start of attendance at the new site as the beginning of incubation and used a 90-day cutoff for successful breeding, incorporating 30 days of incubation (Shields 2014) in addition to the 60-day fledging period.…”

Section: Nesting Successmentioning

confidence: 89%

“…Nestlings were color-banded at 3-4 weeks of age to ensure that they could be followed after leaving the nest site. For full details of nest productivity monitoring methods and results, see Lamb (2016) and Lamb et al (in review).…”

Section: Nesting Successmentioning

confidence: 99%

Behavioral and reproductive effects of bird-borne data logger attachment on Brown Pelicans (Pelecanus occidentalis) on three temporal scales

Lamb

Satgé

Fiorello³

et al. 2016

J Ornithol

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Although the use of bird-borne data loggers has become widespread in avian field research, the effects of capture and transmitter attachment on behavior and demographic rates are not often measured. Tag-and capture-induced effects on individual behavior, survival and reproduction may limit extrapolation of transmitter data to wider populations. However, measuring individual responses to capture and tagging is a necessary step in developing research techniques that minimize negative effects. We measured the short-term behavioral effects of handling and GPS transmitter attachment on Brown Pelicans under both captive and field conditions, and followed tagged individuals through a full breeding season to assess whether capture and transmitter attachment increased rates of nest abandonment or breeding failure. We observed slight increases in preening among tagged individuals 0-2 h after capture relative to controls that had not been captured or tagged, with a corresponding reduction in time spent resting. One to three days post-capture, nesting behavior of tagged pelicans resembled that of neighbors that had not been captured or tagged. Eighty-eight percent of tagged breeders remained at the same nest location for more than 48 h after capture, attending nests and chicks for an average of 49 days, and 51% were assumed to successfully fledge young. Breeding success was driven primarily by variation in location; however, sex and handling time also influenced the probability of successful breeding in tagged pelicans, suggesting that individual characteristics and the capture process itself can confound the effects of capture and transmitter attachment. We conclude that pelicans fitted with GPS transmitters exhibit comparable behaviors to untagged individuals within a day of capture and that GPS tracking is a viable technique for studying behavior and demography in this species. We also identify measures to minimize post-capture nest abandonment rates in tracking studies, including minimizing handling time and covering nests during processing.

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“…The weak condition of urban birds may be also linked to the nutritional constraints that they suffer during early-life, which could negatively affect body condition in adulthood (Bókony et al, 2010;Seress et al, 2012), even if the restriction diminish at later life stages (Liker et al, 2008). Body condition, especially during development, is often positively correlated with pre-and post-fledgling survival rates (Lamb et al, 2016); consequently, poor condition is often observed in a declining population such as urban House Sparrows (Dulisz et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

The Influence of Urban Environments on Oxidative Stress Balance: A Case Study on the House Sparrow in the Iberian Peninsula

et al. 2017

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The House Sparrow is a globally distributed species and is closely associated with anthropised environments. They are well-adapted to urban life; therefore the decline of their populations in Europe represents an unexpected event that demands an investigation into its causes. Causes that have promoted this decline are not well-known, but one of the highlighted hypotheses is an increase of oxidative stress linked to the toxicity of pollution in urban areas. From an ecophysiological perspective, oxidative damage, antioxidant defense, and oxidative balance are considered reliable indicators of environmental stressors such as pollutants. To carry out this study, blood samples were collected from House Sparrows in three different habitats that varied in terms of urbanization degree: urban, suburban, and rural; during the winter and breeding season. According to our results, urban sparrows showed higher levels of oxidative damage and higher activity of antioxidant enzymes, but lower antioxidant capacity in comparison with the rural birds; and these differences especially increase during the breeding season. The maintenance of oxidative balance increases in an urban environment in comparison to a rural one; we suggest that the high level of pollution and the poor quality diet linked to urban environments. The breeding season is expected to be particularly challenging for the oxidative balance of urban birds, when the reallocation of resources between self-maintenance and reproduction may be critical due to the scarcity of antioxidants found in urban areas. This study may contribute to determining the causes of the population decrease of House Sparrows in cities.

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Physical condition and stress levels during early development reflect feeding rates and predict pre- and post-fledging survival in a nearshore seabird

Cited by 17 publications

References 69 publications

Influence of density‐dependent competition on foraging and migratory behavior of a subtropical colonial seabird

Influence of density‐dependent competition on foraging and migratory behavior of a subtropical colonial seabird

Behavioral and reproductive effects of bird-borne data logger attachment on Brown Pelicans (Pelecanus occidentalis) on three temporal scales

The Influence of Urban Environments on Oxidative Stress Balance: A Case Study on the House Sparrow in the Iberian Peninsula

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