Inter-annual site fidelity and breeding origins of Gray-cheeked Thrushes in white sand forests of the Peruvian Amazon.

Ungvari‐Martin, Judit; Heckscher, Christopher M.; Hobson, Keith A.

ABSTRACT White sand terra firme forests are unusual ecosystems scattered across Amazonia, covering just 3% of the basin. These forests differ from surrounding forests in their scleromorphic vegetation, low nutrient content, and propensity to harbor endemics. We report the capture of 62 Gray-cheeked Thrushes ( Catharus minimus) during a study of the understory avifauna of Amazonian white sand forests near Iquitos, Peru, conducted from 20 June to 8 December 2010-2012. We captured and banded Gray-cheeked Thrushes in white sand ( N = 57) and adjacent weathered clay ( N = 5) terra firme forests. Sampling for three consecutive days at 19 different sites each year, the inter-annual site fidelity rate of Gray-cheeked Thrushes was 4.8% ( N = 3). One bird banded in 2010 was recaptured in 2012. Of the 62 birds, 19.3% ( N = 12) were recaptured on subsequent days. All recaptures were in white sand forests. The 19.3% recapture rate of Gray-cheeked Thrushes from sites re-sampled no more than 2 d in a given year suggests the presence of settled and perhaps territorial birds. Using rectrices from 12 Gray-cheeked Thrushes, stable-hydrogen isotope analyses (δ2H) suggest that the geographic breeding or natal origin of all sampled birds was likely northwestern North America. Our results suggest that Gray-cheeked Thrushes exhibit site fidelity and may concentrate in white sand forests-an uncommon and scattered ecosystem type in western Amazonia. However, annual tracking of individual Gray-cheeked Thrushes is needed to fully assess regional patterns of settlement and movement, and the connectivity between breeding and wintering areas.

AMAZON River Region; BIRD breeding; THRUSHES; FORESTS & forestry; WHITE sand

Journal of Field Ornithology, 2016, Vol 87, Issue 1, p55

0273-8570

Academic Journal

10.1111/jofo.12133