Sulfur Isotopes Link Overwinter Habitat Use and Breeding Condition in Double-Crested Cormorants

Hebert, Craig E.; Bur, Michael T.; Sherman, David R.; Shutt, J. Laird

doi:10.1890/07-1278.1

Cited by 40 publications

(48 citation statements)

References 35 publications

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“…Marine sulphate generally has higher δ 34 S values (21‰ for phytoplankton) than terrestrial or freshwater derived sulphates (2–8‰ for upland plants) and therefore sulphur isotope analysis has been extensively used in species that use estuarine habitats (Peterson & Howarth, 1987; Connolly et al , 2004; Olin et al , 2012). In addition to directly tracing nutrient sources to an organism, δ 34 S has been used to track migratory behaviours of birds, regarding overwintering and breeding habitats (Lott et al , 2003; Hebert et al , 2008), and to reconstruct Chinook salmon Oncorhynchus tshawytscha (Walbaum 1792) life history from the larval to adult stages (Weber et al , 2002).…”

Section: Alternative Stable‐isotope Tracersmentioning

confidence: 99%

Stable isotopes and elasmobranchs: tissue types, methods, applications and assumptions

Hussey

MacNeil

Olin

et al. 2012

Journal of Fish Biology

229

212

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Stable-isotope analysis (SIA) can act as a powerful ecological tracer with which to examine diet, trophic position and movement, as well as more complex questions pertaining to community dynamics and feeding strategies or behaviour among aquatic organisms. With major advances in the understanding of the methodological approaches and assumptions of SIA through dedicated experimental work in the broader literature coupled with the inherent difficulty of studying typically large, highly mobile marine predators, SIA is increasingly being used to investigate the ecology of elasmobranchs (sharks, skates and rays). Here, the current state of SIA in elasmobranchs is reviewed, focusing on available tissues for analysis, methodological issues relating to the effects of lipid extraction and urea, the experimental dynamics of isotopic incorporation, diet-tissue discrimination factors, estimating trophic position, diet and mixing models and individual specialization and niche-width analyses. These areas are discussed in terms of assumptions made when applying SIA to the study of elasmobranch ecology and the requirement that investigators standardize analytical approaches. Recommendations are made for future SIA experimental work that would improve understanding of stable-isotope dynamics and advance their application in the study of sharks, skates and rays.

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Section: Alternative Stable‐isotope Tracersmentioning

confidence: 99%

Stable isotopes and elasmobranchs: tissue types, methods, applications and assumptions

Hussey

MacNeil

Olin

et al. 2012

Journal of Fish Biology

229

212

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“…Expansion of the aquaculture industry in the LMRV has likely enhanced the food supply for wintering cormorants (Weseloh and Ewins , Glahn et al , Blackwell et al , Hebert et al , King et al ). Studies of cormorants collected in the Mississippi Delta have shown that they improve their overwinter body condition by foraging at aquaculture facilities (Glahn and Stickley , Glahn et al ).…”

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confidence: 99%

Population dynamics of double‐crested cormorants in two interior breeding areas

Chastant¹,

King

Weseloh³

et al. 2013

J Wildl Manag

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Because of rapid population expansion, conflicts between double‐crested cormorants (Phalacrocorax auritus) and humans have increased, particularly at aquaculture facilities in the Lower Mississippi River Valley (LMRV), United States. Although key demographic information on the Interior population is sparse, management decisions for population reduction are already in place across their breeding range. New evidence suggests the Appalachian Mountains may act as a migration divide for Interior cormorants, causing some birds to migrate between LMRV and the western Great Lakes, whereas others migrate between Florida and the eastern Great Lakes. Most of the banded cormorants recovered near LMRV aquaculture facilities were banded as nestlings at colonies from the central Great Lakes west to the northern Great Plains. We selected 2 geographically distinct Interior cormorant breeding areas: west of the Great Lakes in Lake of the Woods (LOW) and eastern Lake Ontario (ELO), located on either side of the migration divide in the province of Ontario, Canada, to study population dynamics. We used age‐specific classes for our mark‐recapture analysis (Program MARK) on data collected from 9,498 color‐banded cormorants during the breeding seasons of 2000–2008. Adult survival was the same for both areas (LOW = 0.84 ± 0.09 SE, ELO = 0.83 ± 0.05 SE). Finite rates of population growth (λ) were also similar (LOW = 1.01, ELO = 0.97) and sensitivity analyses indicated that adult survival was the most influential vital rate contributing to λ for both breeding areas. However, young‐of‐the‐year survival estimates were distinctly less in ELO (0.19 ± 0.02 SE) than in LOW (0.45 ± 0.10 SE) and sensitivity analysis revealed that young‐of‐the‐year survival played a key role in ELO population growth. Moreover, ELO breeding area fidelity (F) was much greater (0.94 ± 0.05 SE) than the F estimates for all age classes in LOW (between 0.68 ± 0.19 SE and 0.80 ± 0.13 SE). Considering these regional demographic differences, we recommend that future management efforts be based on migratory flyways within the Interior population. © 2013 The Wildlife Society

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“…Peak exposure to infection occurs early in the breeding season with dissipating exposure as the season progresses (Rausch 1983). Furthermore, there is some suspicion that male and female cormorants use different habitats (Tobin et al 2002, Hebert et al 2008): a suspicion that was confirmed for the birds used in this study with stable isotope analysis (Robinson et al unpubl. data).…”

Section: Discussionmentioning

confidence: 57%

Male‐biased parasitism by common helminths is not explained by sex differences in body size or spleen mass of breeding cormorants Phalacrocorax auritus

Robinson

Forbes²,

Hebert³

et al. 2008

Journal of Avian Biology

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In vertebrates, males are often more parasitised than conspecific females. This bias in parasitism might result from sex differences in parasite exposure and/or susceptibility to infection. Such information is important for testing hypotheses about allocation of resources to life histories of males and females and for testing hypotheses about factors thought to influence parasite fitness and parasite dynamics. We tested whether double‐crested cormorants Phalacrocorax auritus exhibit male‐biased parasitism by gut helminths. The prevalence of nematode Contracaecum spp. and trematode Drepanocaphalus spathans infections was ∼90% and 39%, respectively. Cestode, primarily Paradilepis caballeroi and acanthocephalan Andracantha gravida infections were less common (<10%). Male and female cormorants did not differ in prevalence of infection by any helminth species. However, males had twice the abundance and intensity of Contracaecum spp. infections and twice the intensity of D. spathans infections than found in females. For common parasites showing male‐biased parasitism, degree of parasitism was also unrelated to body size or mass in either sex. Males and females did not differ in spleen mass and spleen mass was unrelated to abundance of common parasites. Furthermore, abundance of trematodes and nematodes was not correlated. At present, male biases in parasitism by nematodes and trematodes in cormorants are independent patterns that remain unexplained, but are most likely attributable to sex differences in exposure and/or immunological differences not yet assessed.

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Sulfur Isotopes Link Overwinter Habitat Use and Breeding Condition in Double-Crested Cormorants

Cited by 40 publications

References 35 publications

Stable isotopes and elasmobranchs: tissue types, methods, applications and assumptions

Stable isotopes and elasmobranchs: tissue types, methods, applications and assumptions

Population dynamics of double‐crested cormorants in two interior breeding areas

Male‐biased parasitism by common helminths is not explained by sex differences in body size or spleen mass of breeding cormorants Phalacrocorax auritus

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