Meeting Abstract

P3.63  Wednesday, Jan. 6  Thermal stress during the pre-incubation period alters development, disrupts hatch synchrony, and reduces egg viability in developing northern bobwhites REYNA, K.S.*; BURGGREN, W.W.; University of North Texas; University of North Texas Reyna@unt.edu

Northern bobwhites (Colinus virginianus) are precocial game-birds experiencing population declines concurrent with climate warming. We sought to describe the relationship between high temperatures (Ta) and the ontogeny of northern bobwhites. We hypothesized that bobwhite embryos subjected to hyperthermic pre-incubation conditions would exhibit altered development, decreased hatch rates, and reduced hatchling metabolism. For the 12 days prior to incubation (the pre-incubation period), bobwhite eggs were exposed to 1 of 5 thermal treatments: low-fluctuating Ta (LF; 25–40°C), high-fluctuating Ta (HF; 30–45°C), or treatments of HF during pre-incubation days 1–4 (H1), 4–8 (H2), or 9–12 (H3) with LF during the remainder of pre-incubation. Normal incubation followed (23d @ 37.5°C). Morphologically, HF eggs developed more (stage 15) during the pre-incubation period than LF eggs (stage 4). Eggs from all treatment groups lost ~15% of fresh egg mass during the experiment; significantly more than control eggs (11%). Hatchlings from H1 and H2 groups had lower wet mass than control, HF and LF treated eggs (P=0.02). Physiologically, HF embryos had higher mean oxygen consumption (30 µl•min^-1 stpd) than all other groups (15–20 µl•min^-1 stpd) on day 10 of incubation; however no difference was detected during the remainder of incubation or as hatchlings. Mean hatch rates were lower for HF eggs (5%) compared to LF (52%) and Control (85%). The significantly reduced hatch rates experienced by groups receiving high, fluctuating heat suggest that the embryonic susceptibility of the bobwhite life-cycle contributes to population declines in the semi-arid regions of their range and may be a factor in population declines concurrent with climate warming.