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White-winged dove ( Zenaida asiatica L.) exposure to environmentally accessible lead is a management concern. Detectable concentrations of lead were found in 142 (66%) of 214 white-winged doves collected in 2002 and 2003 at two wildlife management units in South Texas. Mean ± SD lead concentration was 0.70 ± 1.10 μg/g dry weight and ranged from ND to 11.01 μg/g dw. Lead concentrations were significantly lower in the 2002 samples, but similar between management units, age, and gender. White-winged doves in South Texas are being exposed to lead in the environment with some reaching subclinical to toxic levels. [ABSTRACT FROM AUTHOR]

The carbon isotope composition of an animal’s breath reveals the composition of the nutrients that it catabolizes for energy. Here we describe the use of Keeling plots, a method widely applied in ecosystem ecology, to measure the δ13C of respired CO2 of small vertebrates. We measured the δ13C of Rufous Hummingbirds (Selasphorus rufus) in the laboratory and of Mourning (Zenaida macroura) and White-winged (Z. asiatica) Doves in the field. In the laboratory, when hummingbirds were fed a sucrose based C3 diet, the δ13C of respired CO2 was not significantly different from that of their diet (δ13CC3 diet). The δ13C of respired CO2 for C3 fasted birds was slightly, albeit significantly, depleted in δ13C relative to δ13CC3 diet. Six hours after birds were shifted to a sucrose based C4 diet, the isotopic composition of their breath revealed that birds were catabolizing a mixture of nutrients derived from both the C3 and the C4 diet. In the field, the δ13C of respired CO2 from Mourning and White-winged Doves reflected that of their diets: the CAM saguaro cactus (Carnegeia gigantea) and C3 seeds, respectively. Keeling plots are an easy, effective and inexpensive method to measure δ13C of respired CO2 in the lab and the field. [ABSTRACT FROM AUTHOR]