Egg production in a coastal seabird, the glaucous-winged gull (Larus glaucescens), declines during the last century.
Reads0
Chats0
TLDR
It is demonstrated that glaucous-winged gull investment in egg production has declined significantly over the past ∼50–100 y, with such changes potentially contributing to recent population declines and the incremental long-term impoverishment of a coastal marine ecosystem bordering one of North America's rapidly growing urban areas.Abstract:
Seabirds integrate information about oceanic ecosystems across time and space, and are considered sensitive indicators of marine conditions. To assess whether hypothesized long-term foodweb changes such as forage fish declines may be reflected in a consumer's life history traits over time, I used meta-regression to evaluate multi-decadal changes in aspects of egg production in the glaucous-winged gull (Larus glaucescens), a common coastal bird. Study data were derived from literature searches of published papers and unpublished historical accounts, museum egg collections, and modern field studies, with inclusion criteria based on data quality and geographic area of the original study. Combined historical and modern data showed that gull egg size declined at an average of 0.04 cc y−1 from 1902 (108 y), equivalent to a decline of 5% of mean egg volume, while clutch size decreased over 48 y from a mean of 2.82 eggs per clutch in 1962 to 2.25 in 2009. There was a negative relationship between lay date and mean clutch size in a given year, with smaller clutches occurring in years where egg laying commenced later. Lay date itself advanced over time, with commencement of laying presently (2008–2010) 7 d later than in previous studies (1959–1986). This study demonstrates that glaucous-winged gull investment in egg production has declined significantly over the past ∼50–100 y, with such changes potentially contributing to recent population declines. Though gulls are generalist feeders that should readily be able to buffer themselves against food web changes, they are likely nutritionally constrained during the early breeding period, when egg production requirements are ideally met by consumption of high-quality prey such as forage fish. This study's results suggest a possible decline in the availability of such prey, and the incremental long-term impoverishment of a coastal marine ecosystem bordering one of North America's rapidly growing urban areas.read more
Citations
More filters
feathers collected in the Pacific Northwest of North America
TL;DR: The authors used stable isotope (δ(13)C, δ(15)N) analysis of feathers from glaucouswinged gulls (Larus glaucescens) in a heavily disturbed region of the northeast Pacific to ask whether diets of this generalist forager changed in response to shifts in food availability over 150 years, and whether any detected change might explain long-term trends in gull abundance.
Journal ArticleDOI
Changing gull diet in a changing world: A 150‐year stable isotope (δ13C, δ15N) record from feathers collected in the Pacific Northwest of North America
TL;DR: Stable isotope analysis of feathers from glaucous-winged gulls in a heavily disturbed region of the northeast Pacific suggests a long-term decrease in diet quality linked to declining fish abundance or other anthropogenic influences, and may help to explain regional population declines in this species and other piscivores.
Journal ArticleDOI
Egg cannibalism in a gull colony increases with sea surface temperature
James L. Hayward,Lynelle M. Weldon,Shandelle M. Henson,Libby C. Megna,Brianna G. Payne,Andre E. Moncrieff +5 more
TL;DR: Food-stressing surface feeders such as gulls, diminishing energy intake and lengthening foraging bouts, and increasing levels of cannibalism could lead to declining populations in the absence of compensatory adaptive modifications or range shifts are tested.
Journal ArticleDOI
A three‐generational study of In ovo exposure to PBDE‐99 in the zebra finch
TL;DR: It is suggested that egg levels as low as 10 ng/g BDE‐99 may affect reproduction in small passerines by reducing clutch size and no evidence of effects over the longer term and in successive generations is found.
References
More filters
Journal ArticleDOI
Temperature during egg formation and the effect of climate warming on egg size in a small songbird
TL;DR: Long-term data on egg size variation are analyzed in relation to ambient temperatures in a southern European population of pied flycatchers where breeding phenology has not matched the spring advancement in the last decades, indicating that egg breadth, but not egg length, has decreased significantly along the 16-year period.
Journal ArticleDOI
Should avian egg size increase as a result of global warming? A case study using the red-backed shrike (Lanius collurio)
TL;DR: This paper presents the first evidence that avian egg size decreased significantly in a long-term study and concludes that the decrease in egg volume in the studied population might result as a consequence of a number of factors, including changes in temperature, as well as in food supply.
Journal ArticleDOI
An Assessment of PCBs and OC Pesticides in Eggs of Double-crested (Phalacrocorax auritus) and Pelagic (P. pelagicus) Cormorants from the West Coast of Canada, 1970 to 2002
TL;DR: The data suggest that contaminant levels in cormorants have now stabilized at low levels throughout the resident population, and it seems more probable that ecological variables, particularly changing prey and predator dynamics, drove the reductions in population size.
Related Papers (5)
Nutritional constraints on egg formation in the lesser black-backed gull : an experimental study
A Global Map of Human Impact on Marine Ecosystems
Benjamin S. Halpern,Shaun Walbridge,Kimberly A. Selkoe,Kimberly A. Selkoe,Carrie V. Kappel,Fiorenza Micheli,Caterina D'Agrosa,Caterina D'Agrosa,John F. Bruno,Kenneth S. Casey,Colin M. Ebert,Helen E. Fox,Rod Fujita,Dennis Heinemann,Hunter S. Lenihan,Elizabeth M. P. Madin,Matthew T. Perry,Elizabeth R. Selig,Elizabeth R. Selig,Mark Spalding,Robert S. Steneck,Reg Watson +21 more