Survival estimates, mortality patterns, and population growth of Fennoscandian mallards Anas platyrhynchos

• Main Authors: Gunnarsson, Gunnar, Elmberg, Johan, Dessborn, Lisa, Jonzén, Niclas, Pöysä, Hannu, Valkama, Jari
• Format: Article in Journal/Newspaper
• Language: English
• Published: Högskolan Kristianstad, Avdelningen för Naturvetenskap 2008
• Subjects: Biological Sciences; Biologiska vetenskaper; Pulli; Fennoscandian
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-642

Long-term mallard capture-recapture data from Sweden and Finland were analyzed to describe temporal mortality patterns and reasons. We used program MARK and Seber models to estimate annual survival (S) and recovery (r) rates. Survival rates were used in a Monte Carlo simulation to evaluate the correspondence between observed and predicted annual population sizes of a Finnish sub-population. About 90% of recovered birds died from hunting. Most recoveries were from the hunting season, and more males than females were shot. Predation was the most common cause of natural mortality. Finnish capture-recapture data fitted best the global model in which survival and recovery vary with age and sex. Annual survival and recovery rates for adult and juvenile males and females were overlapping, ranging from 0.46 to 0.90 (survival) and 0.07 to 0.17 (recovery), whereas pulli had lower survival rates (0.21-0.42). Pulli that were successfully sexed at the time of ringing had higher recovery rates (female pulli: 0.23; male pulli: 0.32) than juveniles and adults. Density-dependent fledgling production was detected in the Finnish sub-population and was accounted for in the Monte Carlo simulation, which estimated predicted breeding population size quite well, although one of the observed annual values (2003) fell outside the 95% confidence limits.