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Scharf HM, Abolins-Abols M, Stenstrom KH, Tolman DT, Schelsky WM, Hauber ME. Exposure to a mimetic or non-mimetic model avian brood parasite egg does not produce differential glucocorticoid responses in an egg-accepter host species. Gen Comp Endocrinol 2021; 304:113723. [PMID: 33539900 DOI: 10.1016/j.ygcen.2021.113723] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 01/20/2021] [Accepted: 01/22/2021] [Indexed: 10/22/2022]
Abstract
Avian obligate brood parasitism, a reproductive strategy where a parasite lays its egg into the nest of another species, imposes significant fitness costs upon host parents and their offspring. To combat brood parasitism, many host species recognize and reject foreign eggs (rejecters), but others are accepters that raise the parasitic progeny. Some accepter hosts may be unable to grasp or pierce parasitic eggs even if they recognize them as foreign eggs in the clutch, whereas other accepters may not have evolved the cognitive skillsets to recognize dissimilar eggs in the nest. Here we assessed the endocrine responses of an accepter host species to model parasitic eggs to address these two alternatives. We experimentally parasitized nests of a locally common host of the brood-parasitic brown-headed cowbird (Molothrus ater), the prothonotary warbler (Protonotaria citrea; a cowbird-egg accepter), with a mimetic or non-mimetic model cowbird-sized egg. Our goal was to determine whether they perceived the non-mimetic egg as a greater stressor by measuring circulating corticosterone levels. We added eggs to nests during the incubation stage and obtained blood plasma samples from females on the nest 2 h later, using females with unmanipulated clutches as controls. Incubating females showed no differences in baseline plasma corticosterone levels between our different treatments. We conclude that exposure to foreign eggs does not activate the hypothalamic-pituitary-adrenal axis of prothonotary warbler hosts in this experimental paradigm.
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Affiliation(s)
- H M Scharf
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois Urbana-Champaign, IL, USA.
| | - M Abolins-Abols
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois Urbana-Champaign, IL, USA; Department of Biology, University of Louisville, KY, USA
| | - K H Stenstrom
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois Urbana-Champaign, IL, USA
| | - D T Tolman
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois Urbana-Champaign, IL, USA
| | - W M Schelsky
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign, IL, USA
| | - M E Hauber
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois Urbana-Champaign, IL, USA; Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign, IL, USA; Hanse-Wissenschaftskolleg (Institute for Advanced Study), Delmenhorst 27753, Germany
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