Winter habitat disturbance influences density and territory size of a Neotropical migratory warbler

• Published in: Journal of ornithology 2017, Vol.158 (1), p.63-73
• Main Authors: Ruiz-Sánchez, Angelina, Renton, Katherine, Rueda-Hernández, Rafael
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; Ecology; Fish & Wildlife Biology & Management; Habitats; Life Sciences; Migratory birds; Original Article; Populations; Reproduction; Reproductive behavior; Zoology
• ISSN: 2193-7192; 2193-7206
• DOI: 10.1007/s10336-016-1368-9

Migratory birds face population declines attributed to habitat loss and modification in the wintering grounds, which may influence body condition, time of arrival to breeding grounds, and future reproductive opportunities. Despite this, very little is known of the wintering ecology of migratory birds. During three winter seasons, we assessed Wilson’s Warbler ( Cardellina pusilla ) density, territory size, and body condition at three cloud forest sites in southeast Mexico, with differing degrees of habitat disturbance and forest cover: preserved 125 ha of cloud forest actively protected for 40 years; moderately disturbed site of 67.5 ha of cloud forest under protection for 29 years; and highly disturbed unprotected site with 6.5 ha of cloud forest. We determined warbler density using 20 unlimited-radius point-counts at each site. We also captured and measured birds ( n  = 74) over three years, to obtain a body condition index, and re-sighted color-banded birds to determine individual territory size at each site. Bird densities were two times greater and territory size was smaller in the conserved forest site compared to disturbed sites with lower forest cover. However, there was no significant difference among sites in the body condition index of territorial birds. Furthermore, territory size and body condition were relatively constant among years for birds in conserved forest, but exhibited high inter-annual fluctuations at disturbed forest sites. Considering the higher bird density, smaller territory size, and inter-annually consistent body condition at the conserved cloud forest site, we propose that this represents higher quality wintering habitat for Wilson’s Warblers.