Breeding ecology of two tit species (paridae) at METU campus

Kavak, Pınar
Use of nest boxes is a common method to perform ecological research on hole nesting species. The family Paridae is the subject of longest running studies in the field of avian ecology. Despite the usefulness of such an approach, only a handful studies utilizing next boxes have been completed in Turkey. The aim of this study is to investigate the breeding ecology of Paridae species at METU campus , Ankara, which offers marginal habitat for most tree-dependent species. A total of 50 nest boxes were attached to tree trunks in three forested patches of the campus in early 2013. Data on breeding parameters (laying date, clutch size, breeding success, body measurements, predation rate) were collected with weekly visits during late March until July in 2013- 2015. Two species have used the nest boxes placed: Great Tit (Parus major) and Coal Tit (Parus ater). In total, 40 nest boxes were occupied by either species during the study, and 26 of those were used to calculate breeding parameters. The proportion of occupied next boxes was found to significantly increase further away from buildings or asphalt roads. Both species started nesting in the first week of April. Mean egg laying dates were 21st of April and 4th of May, and average clutch size were 7.5 and 6.8 for Coal Tits and Great Tits, respectively. The fate of nesting attempts pooled over three years were as follows: 42.5% predated, 40.0% successful, 15.0% deserted or predated, and 2.5% unknown. The number of fledglings per nest was 4.0 and 1.4 for Coal Tits and Great Tits, respectively. The main identified predator was magpie (Pica pica) while the other predators were Caspian snake (Dolichophis caspius), fox (Vulpes vulpes) and domestic cat (Felis catus). Although the findings on laying date and clutch size are comparable to other study sites at similar latitudes, predation rates, and hence the overall rate of breeding failure, are among the highest recorded. Very high densities of magpies at METU campus could be the reason. Our study indicates that the introduction of nest boxes might have created an ecological trap, particularly for Great Tits, leading to a sink population that can only persist with immigration from neighboring habitats. However further research, including some on success rates at nests in natural cavities, should be conducted in order to assess the full impact of nest boxes on tit populations at METU campus.
Citation Formats
P. Kavak, “Breeding ecology of two tit species (paridae) at METU campus,” M.S. - Master of Science, Middle East Technical University, 2015.