Temperature-associated dynamics of songbird winter distributions and abundances.
Using Christmas Bird Count data, we analyze the annual spatio-temporal abundances of six passerine species in the upper Great Plains, US (1960-1990). This study provides new insight into how global warming could cause separation of species within present-day communities. We find that winter relative abundances of similarly-sized songbirds are differentially affected by ambient winter temperature. As such, average annual winter temperature fluctuations (i.e., severity of winter) are significantly (P < 0.05) correlated with the relative abundances of three species while the other three are not. Our conditional probability-of-occurrence analysis indicates that the abundances of the three temperature-associated species declined markedly below -4 degrees C while the abundances of the other three species fluctuated little from 8 degrees C to -16 degrees C. We conclude that even in colder climates i) the winter distributions of some, but not all, songbirds are directly or indirectly limited by temperature; and ii) these birds have dynamic abundances that can quickly respond to temperature changes.
Butler
J Russell
JR
Department of Pre-professional Studies, Florida Hospital College of Health Sciences, Orlando, FL 32803, USA. russ.butler@fhchs.edu
MacMynowski
Dena P
DP
Laurent
Chad
C
Root
Terry L
TL
D000818:Animals; D017752:Greenhouse Effect; D011156:Population Density; D011157:Population Dynamics; D012621:Seasons; D020308:Songbirds; D013696:Temperature; D014481:United States