Article Abstract:
The patterns of egg laying in the ptarmigan are studied. The order and frequency of gaps seen within and between species is possibly due to nutrient constraints on egg formation in conjunction with physiological mechanisms which control a time-window for egg laying. The comparison of timing of laying during the day, laying gaps, and laying rates for white-tailed ptarmigan and willow ptarmigan show that both species tend to lay eggs near midday, but the willow ptarmigan has little laying gaps and a faster laying rate than white-tailed ptarmigan. Laying gaps were not related to spring body condition.
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Article Abstract:
The feasibility of using estradiol cypionate (ECP) to improve the survival ofWillow Ptarmigans in captivity was evaluated. Experiments were performed wherein captured male ptarmigans were placed in cages and subsequently injectedwith either 0.1 or 0.2 milligram of 17beta-estradiol in cottonseed oil cypionate. The caged birds were checked visually each day to monitor survival. Results revealed that low-dosage injections of ECP greatly enhanced survival incaptivity for Willow Ptarmigans.
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Article Abstract:
Research is presented concerning the recruitment from nearby populations and the dispersal of White-tailed Ptarmigan at four study sites in Colorado. The greater dependance of populations on female rather than male recruitment is discussed.
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