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9/28/2018 | 8:50 AM - 9:05 AM | Dispersal, Survival and Causes of Mortality of Juvenile Rock Ptarmigan Lagopus Muta in Southern Europe | Eccles Conference Center Auditorium

Dispersal, Survival and Causes of Mortality of Juvenile Rock Ptarmigan Lagopus Muta in Southern Europe

Data on dispersal distances and survival of juvenile grouse are important for understanding population regulation processes. We studied natal dispersal and survival in juvenile rock ptarmigan in the French Alps and the Pyrenees between 1999 and 2017, by radio-tracking 113 fully-grown chicks captured in September. Natal dispersal occurred in two phases, fall (October and November) and to a lesser extent spring (April-May). Distances travelled by young birds during their first year varied according to sex (females > males) and site (Pyrenees > Alps). The mean natal dispersal distances for females compared to males were 6.6 km vs. 3.9 km in the Pyrenees and 3.7 km vs. 1.0 km in the Alps. Monthly juvenile survival was estimated from 1st September to 30th June using the known fate option in Program MARK. The best model explaining the variations in survival probabilities included the effect of month, with marginal effects of sex and site. Our results indicated two periods of high juvenile mortality. The first was September-November coinciding with brood breakup, movements to winter range and the molt into winter plumage. The second was June when nests were initiated. While not significant, our data suggested that juvenile survival was higher in the Pyrenees than in the Alps. Furthermore, despite greater dispersal distances travelled by juvenile females, their survival rate tended to be greater than that of males (0.68 ± 0.07 SE vs. 0.62 ± 0.07 SE). Predation accounted for 71% of the causes of mortality, with predation by raptors predominant in the Pyrenees.

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Presenters/Authors

Claude Novoa (), Office National de la Chasse et de la Faune Sauvage, claude.novoa@oncfs.gouv.fr;