The Cuckoo and its host species in forest-steppe part of Sumy region. - N.P. Knysh. - Berkut. 9 (1-2). 2000. P. 51-73.
Data were collected in Sumy district in 1960-1990s. 70 eggs and 21 nestlings of the Cuckoo were found in nests of 12 species of passerine birds (Tables 1, 2). Intensity of “infectiousness” was the highest in the Marsh Warbler - 22,68 %, for all host species it makes 4,90 %. Population density in different habitats fluctuates from 3,25 till 25,70 ind./km2. Only females of grey morph are occurred. Arrival (first cuckoo) of males are observed 26.04 ±1,1 days (n = 38), last cuckoo – 4.07 ±1,8 days (n = 10). First trills (arrival) of females – 10.05 ±1,6 days (n = 8), last ones – 3.07 ± 2,7 days (n = 8). The last birds were observed 21.08 ± 4,5 days (n = 10). Singing intensity is the highest in the morning and evening (Fig. 1). First eggs are laid on average 25.05 ± 0,9 days (n = 11), last eggs – 28.06 ± 2,9 days (n = 7). In 8 cases (16,0 %) eggs were laid in empty nests, 39 (78,0 %) – in incomplete clutches or in day of completion, 3 (6,0 %) – eggs were found in nests after beginning of incubation (n = 50). Number of eggs in nest at the time of egg laying by the Cuckoo (n = 45): 0 – 8; 1 – 3; 2 – 7; 3 – 13; 4 – 10; 5 – 4, on average 2,58 ± 0,23. Average number of excepted eggs by the Cuckoo: clutches with 2 eggs – 1,25 ± 0,25 (n = 4), 3 eggs – 1,27 ± 0,19 (n = 11), 4 eggs – 1,10 ± 0,18 (n = 10), 5 eggs – 1,25 ± 0,25 (n = 4). Morphometric parameters of eggs are presented in Tables 1 and 4. 48 eggs (70,59 %) had similarity with eggs of the Marsh Warbler, 12 (17,65 %) – Red-backed Shrike. Breeding success of the Cuckoo varies over a wide range in nests of different bird species (Table 6). On average the hatching success made 43,82 ± 5,29 %, fledging success – 32,58 ± 5,00 %. In total the death of offsprings made 67,42 %. Losses of eggs exceed losses of nestlings in more than in 5 times. Main reasons of death: aversion of eggs (seldom also chicks) – 25,84 %, predation – 13,48 %, abandonment of nests by hosts – 11,24 %, bad weather conditions (hail, heavy shower) – 6,74 % of breeding cases. A part of eggs was destroyed by Cuckoos – 4,49 %, by men – 1,12 %, not developed eggs – 3,37 %. [Russian].
Key words: Cuckoo, Cuculus canorus, Sumy region, ecology, migration, activity, behaviour, breeding, egg, nestling, breeding success, host species.
Address: N.P. Knysh, Sumy pedagogical university, Romenska str. 87, 40002 Sumy, Ukraine.