Comparative study of annual and daily capture-recapture and biometrics of two treecreeper species (Certhia spp.) in the post-breeding season over 23 years in western Hungary

In this study, we detected and compared changes in the annual and daily captures of the Eurasian (Certhia familiaris) and Short-toed Treecreeper (C. brachydactyla) in the timing of their post-breeding movements, in the length of minimum stopover duration (MSD) in the area, and also in biometrics in western Hungary. The birds were captured and ringed, or recaptured from the end of July to the first weekend of November in all years from 2001 to 2023. The annual captures of both species indicated stable populations in this period, with milder February months having a positive effect on annual captures. There were similarities and differences in the movement strategies and habitat selection of the species. During the post-breeding season, the Eurasian Treecreeper was more strongly associated with the scrubland and forest edge than the Short-toed Treecreeper. There were two autumn capture waves in September and October for the Eurasian Treecreepers and just one in September for the Short-toed Treecreepers, which were primarily consisted of birds captured only once. There were no significant differences in wing length of the three capture intervals (July-August, September, October-November) in either species, which suggests that the dynamics of post-breeding movements cannot be explained on the bases of possible differences in the behavior of sexes, ages, or populations. The proportion of birds captured only once was about double of that of stopovers in both species each year. The average real length of stopover duration in the area for Eurasian Treecreepers was 94.25 days, and 84.31 days for Short-toed Treecreepers. The length of MSD in the area was not significantly associated with wing length and body mass in either species. Individuals of both species did not gain fat stores significantly during post-breeding season.