Influence of Latitude on the Winter Abundance of Red-tailed Hawks (Buteo jamaicensis) and American Kestrels (Falco sparverius) in Illinois

Determination Of The Summer Origins Of American Kestrels (Falco Sparverius) Wintering In Northern And Central Illinois

“…When examining the δ 2 Hf values of the male and female migrant American Kestrels, we did not find support for differential sex migration, which has been documented by Willoughby and Cade (1964) and Goodrich et al (2012) and suggested by Groves et al (2013). Male American Kestrels have been documented wintering farther north than female Kestrels departing from similar summer latitudes (Willoughby andCade 1964, Goodrich et al 2012), so we expected to observe more depleted δ 2 Hf values in the female migrants wintering in northern and central Illinois than the males, but this was not the case.…”

“…Wisconsin have been recovered wintering in Mississippi, Missouri, Arkansas, and northern Louisiana (J. E. Eschenbauch personal communication). Therefore, if accurate, the predicted summer origins north of ~44.00°N potentially depict a northward shift in the winter distribution of the American Kestrel, which has been suggested by Goodrich et al (2012), Heath et al (2012), Groves et al (2013), and Paprocki et al (2014). Northward shifts in the winter distribution of several other North American raptor species have also been documented over the past several decades and are potentially being caused by climate change, land-use change, or a combination of both (Goodrich et al 2012, Groves et al 2013, Paprocki et al 2014, Paprocki et al 2017.…”

“…It is unclear whether this is representative of what is truly occurring, is an effect of our sample size, or is the result of some other factor (e.g., inter-individual variation in the δ 2 Hp-δ 2 Hf relationship). Groves et al (2013) observed a male-biased sex ratio in the American Kestrels wintering in northern and central…”