Apparent survival of a range-restricted montane forest bird species is influenced by weather throughout the annual cycle
To conserve small and fragmented populations, we need an understanding of their population dynamics. With a global population estimate of < 120,000, Bicknell's Thrush (Catharus bicknelli) is considered one of the Nearctic-Neotropical migrants at greatest risk of extinction. This range-restri...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Resilience Alliance
2019-12-01
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| Series: | Avian Conservation and Ecology |
| Subjects: | |
| Online Access: | http://www.ace-eco.org/vol14/iss2/art16/ |
| _version_ | 1797972172559351808 |
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| author | Jason M. Hill John D. Lloyd Kent P. McFarland Christopher C. Rimmer |
| author_facet | Jason M. Hill John D. Lloyd Kent P. McFarland Christopher C. Rimmer |
| author_sort | Jason M. Hill |
| collection | DOAJ |
| description | To conserve small and fragmented populations, we need an understanding of their population dynamics. With a global population estimate of < 120,000, Bicknell's Thrush (Catharus bicknelli) is considered one of the Nearctic-Neotropical migrants at greatest risk of extinction. This range-restricted songbird breeds in high-elevation fir (Abies balsamea) forests of the northeastern United States and eastern Canada, and primarily overwinters in forests of the Dominican Republic. The Conservation Action Plan for Bicknell's Thrush identifies numerous actions that may help stem population declines and promote recovery of the species, yet the empirical data needed to prioritize among these actions are lacking. We fit Cormack-Jolly-Seber models with mark-recapture data to test a series of hypotheses about the factors that limit apparent survival in 178 adult Bicknell''s Thrush (50 females and 128 males) captured on the breeding grounds in Vermont (June-July, 2001-2015). We focused on putatively important factors from throughout their annual cycle: cyclical population dynamics of nest predators, and weather effects on food abundance on the breeding and wintering grounds. Apparent survival of Bicknell's Thrush was relatively stable (mean Φ = 0.61, 95% CI: 0.54, 0.68) over our 15-year study, and most strongly associated with fir mast production. Apparent survival was higher following years during which fir trees produced large mast crops (mean Φ = 0.67, 95% CI: 0.55, 0.79), compared to following nonmast years (Φ = 0.56 ± 0.06, 95% CI: 0.43, 0.68). These results are likely driven by the reduced red squirrel density and increased nesting success and site fidelity of adult thrushes following nonmast years. Apparent survival of Bicknell's Thrush was also associated with relatively wet conditions on the wintering grounds in Hispaniola as assessed via the El Niño-Southern Oscillation (ENSO) precipitation index (ESPI). These relatively wet December-March periods are likely linked to greater primary productivity and the local availability of fruits and arthropods consumed by Bicknell's Thrush. Our research provides the most comprehensive examination of potentially limiting factors on Bicknell's Thrush populations to date and suggests future avenues of research exploring the relationship between food availability, survival, and climate change induced reductions in rainfall for the Greater Antilles. |
| first_indexed | 2024-04-11T03:44:13Z |
| format | Article |
| id | doaj.art-5e80181e5a8c4577975b01322871ac65 |
| institution | Directory Open Access Journal |
| issn | 1712-6568 |
| language | English |
| last_indexed | 2024-04-11T03:44:13Z |
| publishDate | 2019-12-01 |
| publisher | Resilience Alliance |
| record_format | Article |
| series | Avian Conservation and Ecology |
| spelling | doaj.art-5e80181e5a8c4577975b01322871ac652023-01-02T03:08:19ZengResilience AllianceAvian Conservation and Ecology1712-65682019-12-01142161462Apparent survival of a range-restricted montane forest bird species is influenced by weather throughout the annual cycleJason M. Hill0John D. Lloyd1Kent P. McFarland2Christopher C. Rimmer3Vermont Center for EcostudiesVermont Center for EcostudiesVermont Center for EcostudiesVermont Center for EcostudiesTo conserve small and fragmented populations, we need an understanding of their population dynamics. With a global population estimate of < 120,000, Bicknell's Thrush (Catharus bicknelli) is considered one of the Nearctic-Neotropical migrants at greatest risk of extinction. This range-restricted songbird breeds in high-elevation fir (Abies balsamea) forests of the northeastern United States and eastern Canada, and primarily overwinters in forests of the Dominican Republic. The Conservation Action Plan for Bicknell's Thrush identifies numerous actions that may help stem population declines and promote recovery of the species, yet the empirical data needed to prioritize among these actions are lacking. We fit Cormack-Jolly-Seber models with mark-recapture data to test a series of hypotheses about the factors that limit apparent survival in 178 adult Bicknell''s Thrush (50 females and 128 males) captured on the breeding grounds in Vermont (June-July, 2001-2015). We focused on putatively important factors from throughout their annual cycle: cyclical population dynamics of nest predators, and weather effects on food abundance on the breeding and wintering grounds. Apparent survival of Bicknell's Thrush was relatively stable (mean Φ = 0.61, 95% CI: 0.54, 0.68) over our 15-year study, and most strongly associated with fir mast production. Apparent survival was higher following years during which fir trees produced large mast crops (mean Φ = 0.67, 95% CI: 0.55, 0.79), compared to following nonmast years (Φ = 0.56 ± 0.06, 95% CI: 0.43, 0.68). These results are likely driven by the reduced red squirrel density and increased nesting success and site fidelity of adult thrushes following nonmast years. Apparent survival of Bicknell's Thrush was also associated with relatively wet conditions on the wintering grounds in Hispaniola as assessed via the El Niño-Southern Oscillation (ENSO) precipitation index (ESPI). These relatively wet December-March periods are likely linked to greater primary productivity and the local availability of fruits and arthropods consumed by Bicknell's Thrush. Our research provides the most comprehensive examination of potentially limiting factors on Bicknell's Thrush populations to date and suggests future avenues of research exploring the relationship between food availability, survival, and climate change induced reductions in rainfall for the Greater Antilles.http://www.ace-eco.org/vol14/iss2/art16/bicknell's thrushcatharus bicknelliclimate interactionel niño-southern oscillation (enso)enso precipitation index (espi)food limitationinterspecific competitionnormalized difference vegetation index (ndvi)population limitationresource pulsetamiasciurus hudsonicus |
| spellingShingle | Jason M. Hill John D. Lloyd Kent P. McFarland Christopher C. Rimmer Apparent survival of a range-restricted montane forest bird species is influenced by weather throughout the annual cycle Avian Conservation and Ecology bicknell's thrush catharus bicknelli climate interaction el niño-southern oscillation (enso) enso precipitation index (espi) food limitation interspecific competition normalized difference vegetation index (ndvi) population limitation resource pulse tamiasciurus hudsonicus |
| title | Apparent survival of a range-restricted montane forest bird species is influenced by weather throughout the annual cycle |
| title_full | Apparent survival of a range-restricted montane forest bird species is influenced by weather throughout the annual cycle |
| title_fullStr | Apparent survival of a range-restricted montane forest bird species is influenced by weather throughout the annual cycle |
| title_full_unstemmed | Apparent survival of a range-restricted montane forest bird species is influenced by weather throughout the annual cycle |
| title_short | Apparent survival of a range-restricted montane forest bird species is influenced by weather throughout the annual cycle |
| title_sort | apparent survival of a range restricted montane forest bird species is influenced by weather throughout the annual cycle |
| topic | bicknell's thrush catharus bicknelli climate interaction el niño-southern oscillation (enso) enso precipitation index (espi) food limitation interspecific competition normalized difference vegetation index (ndvi) population limitation resource pulse tamiasciurus hudsonicus |
| url | http://www.ace-eco.org/vol14/iss2/art16/ |
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