State of the White Stork (Ciconia ciconia) population in Ukraine in 2013. - V.N. Grishchenko, E.D. Yablonovska-Grishchenko. - Berkut. 22 (2). 2013. - P. 90-103.
Monitoring observations on the White Stork population in Ukraine have been carried out since 1992. Their results for the year 2013 have special interest because of a sharp and long cold snap in the third decade of March. We analysed its influence on the population. Data were obtained on 146 monitoring plots in all the regions of Ukraine. They had 1856 occupied nests on the overall area 10.6 ths km2. Migration and breeding phenology, number dynamics and breeding success were studied. The spring migration of storks started early and passed intensively but it was interrupted by the strong cold snap with frosts and snowfalls. It covered whole Ukraine and lasted about a week (22–30.03 in Central Ukraine). The cold did not affect distinctly neither timing of spring migration nor breeding phenology. The mean first arrival date was one of the earliest for the whole period of observations. In separate regions deviations of mean first arrival dates from long-term mean dates (1992–2013) fluctuated from –6.9 to +2.3 (–3.58 ± 0.55 days (± se), 19 regions). Young birds left the nests since 6.07, majority of broods started to fly since mid July. Mean date of the fledge was 22.07 (± 1.2 days, n = 38). The autumn passage went also in usual terms. The first migrating flocks were observed on average on 15.08 (± 1.9 days, n = 10, lim: 6–24.08). Last departures were registered since 14.08 till 29.09 (average – 31.08 ± 1.9 days, n = 33). Rise of the stork population could be expected based on its dynamics in previous years and favourable conditions of wintering but number increasing was fully absent. The average gain of number on study plots made in whole Ukraine only 0,4 ± 1,3 % (n = 119). We found that it was the main consequence of the cold weather in March. This phenomenon manifested differently in various parts of the country. The cold did not affect the stork number in West Ukraine located in the core part of breeding range. It rose in 3,5 ± 1,9 % (n = 44). This value is close to rates in 2011–2012. At the same time, the number in peripheral part of the population near the border of areal (East and South-East Ukraine) decreased (–4,4 ± 2,9 %, n = 19). Differences with West Ukraine are significant (p < 0,05). The population declined also in Central Ukraine. At the local level the picture of number changes was very motley. Tendencies frequently differed even on the nearby plots. We supposed that a part of storks has not reached their habitual breeding areas and settled en route. To it testify also the violation of usual order of nest occupation in many places. Some always occupied “popular” nests remained empty but birds built new ones and renewed deserted habitations. Monitoring observations in the Northern Crimea showed number decreasing and reduction of breeding grounds in 2012–2013. Breeding success was in 2013 very high. Reproductive parameters belong to the best since 2000. Storks raised on average 2.86 ± 0.04 fledged youngs per breeding pair (JZa) and 3.08 ± 0.04 fledged youngs per successful pair (JZm). Only 7.2 ± 0.7 % pairs bred unsuccessful. It was the lowest value of this parameter for all years of monitoring observations. Productivity of breeding rose from the west to the east. Broods had from 1 to 7 fledglings. Majority of stork pairs in Ukraine raised 3 youngs (39.7%, n = 1669). One brood had 7 fledglings (only second case during 22 years) and 4 ones – 6. Despite of high productivity, we found increased proportion of broods with the single fledgling. The degree of this excess rised from the west to the east. It was one more consequence of the cold snap in March. Some part of storks have been weakened and could not bring up more than one chick. In the whole, the year was quite favourable for storks despite of weather cataclysm. The population has successfully sustained the impact of elements. [Russian].
Key words: monitoring, breeding success, number dynamics, migration, phenology, cold snap.
Address: V.N. Grishchenko, Kaniv Nature Reserve; Kaniv, 19000, Ukraine; e-mail: vgrishchenko@mail.ru.