Materials on the biology of Robin in forest-steppe deciduous forests of Sumy region. - N.P. Knysh. - Berkut. 17 (1-2). 2008. - P. 41-60.
Data were collected in Sumy district (NE Ukraine), mainly near the village of Vakalivshchina [51.01 N, 34.55 E], in 1969–2008. Population density of robins makes 60–80 pairs/km² in oak forests, 7,6–9,5 pairs/km² in parks and 13,8 pairs/km² in old graveyards of Sumy city. First birds arrive between 17.03 (2002) and 12.04 (2003), on average 30.03 ± 1,2 days (± SE, n = 29). Spring migration lasts from 6 to 40, on average 24,0 ± 3,4 days (n = 11). Robins sing since the day of arrival till 1–2 ten-days of July, on average till 7.07 ± 1,2 days (n = 10). Egg laying starts in 19–44, on average 32,1 ± 2,0 days (n = 12) after arrival. Nests (n = 101) are built on the ground (45,5% of cases), in hollows (9,9%), artificial nest boxes (41,6%) and other places. Pause between ending of nest building and first egg laying lasts 1–4, on average 1,9 ± 0,4 days (n = 8). The earliest clutches begin between 22.04 (2008) and 7.05 (1991), on average 29.04 ± 1,4 days (n = 14), the latest started clutches were found on 1.07 (2006) and 6.07(1993). There are two peaks of egg laying: in the first ten-day of May and in the first ten-day of June. About 54% of robins lay the second clutch. Brooding lasts 12–15, on average 12,8 ± 0,3 days (n = 10). Full clutches have 5–8, on average 6,56 ± 0,09 eggs (n = 71), their size gradually decreases during the breeding period. The spring clutches have on average 6,76 ± 0,10 eggs (n = 45), the summer ones – 6,23 ± 0,14 (n = 26). Egg measurements vary depending on the clutch size and breeding conditions. Mean egg size: 19,81 ± 0,05 × 15,02 ± 0,03 mm (n = 332). The overall breeding success is 63,5%. Productivity of breeding little depends on site and timing of nesting but very depends on clutch size. Offspring losses during egg laying, brooding and feeding of nestlings made 12,3, 17,4, и 6,8% respectively. Raptors, mainly Martes martes and Dryomys nitedula, have destroyed 22,9% of eggs and nestlings (62,8% from overall losses). In autumn Robins departure since late August, mass migration are observed in September and October. Last birds were registered between 10.10 (1978) and 11.12 (1970), on average 26.10 ± 3,4 days (n = 21). Some Robins can winter. [Russian].
Key words: Robin, Erithacus rubecula, ecology, breeding, clutch, egg, breeding success, migration.
Adress: N.P. Knysh, Sumy Pedagogical University, Dep. of Zoology, Romenska str. 87, 40002, Sumy, Ukraine.