Recruitment Rates, Natal and Breeding Dispersal of Montagu’s Harriers (Circus Pygargus) by Means of Microsatellite Analysis

Abstract

Introduction:Adult philopatry as well as juvenile dispersal and recruitment rates are key factors for population development. We investigated these questions for the first time in an increasing German population of Montagu’s harrier in Frankonia using microsatellite markers.Methods:By means of 16 loci, we genotyped 2265 samples from juvenile and adult female Montagu’s harriers. Parentage and identity tests were used to reconstruct life histories of birds for a 10 year period. Most of the birds were breeding in one or two years. The longest life history was eight years.Results:Adult philopatry was quite high and differed significantly between sexes. We found 73.5% of females to breed < 5 km around the previous nest site (80.4% < 10 km, median nesting distance 2.1 km). All investigated males (n=18) were breeding in a distance of < 5 km (median nesting distance 1.3 km) to the previous nest. Juveniles showed a low recruitment rate (females: 2.9%, males: 4.9%, together 4%). Median natal dispersal distance was 19.1 km for females and 12.3 km for males. We found 29.4% of females and 41.2% of males to be philopatric, as the distance between hatching and first breeding site was < 10 km. Philopatry results mostly agree with data from other European countries.Discussion:Due to strict marker and data selection we received high quality life histories of Montagu’s harriers, which demonstrate that microsatellite analyses are valuable tools in ornithology.Conclusion:Nevertheless, comparison of philopatry and recruitment rates depend directly on the scale used and investigation method and therefore remain a challenge.