SEASONAL SURVIVAL OF GREATER SNOW GEESE AND EFFECT OF HUNTING UNDER DEPENDENCE IN SIGHTING PROBABILITY

摘要: Although much of life-history theory assumes increased mortality at certain stages (e.g., migration), survival rates are rarely estimated on a seasonal basis within the annual cycle migratory species. We variations in long-lived, hunted species presence short-term (between consecutive seasons) and long-term years same season) dependence sighting probabilities. also tested two contrasting hypotheses that hunting is either compensatory or additive to natural mortality. This study was conducted adult female Greater Snow Geese (Chen caerulescens atlantica) from 1990 1998, based 3890 neck-banded birds 13 657 resightings northern breeding grounds summer, southern staging areas spring autumn. Birds were 10-20% more likely be seen autumn if they previous occasion (summer autumn, respectively). 30-40% last season year. Differences behavior according family status (pres- ence absence young) heterogeneity site fidelity may explain probabilities; failure account for this lead biased estimates. Monthly summer (3-mo period) (2.5- mo equal (0.989 ? 0.003, mean 1 SE) showed little variation over years, even though lengthy flights (3000 km each) occurred during these periods. In contrast, monthly winter (from spring, 6.5 mo) lower than other seasons varied significantly (range 0.936 0.021 0.993 0.008). Mean females (corrected neck band loss) 0.96 0.86 winter, 0.83 0.05 whole Natural (i.e., excluding hunting) among did not vary which suggests risk migration repro- duction. There significant inverse relationship between kill rate (b = -1.21 + 0.56), probably general feature long-lived because their low relatively constant does allow them compensate an additional source such as hunting. Contrary theory, we find evidence reproduction entailed cost long-distance migrant bird.