The dynamics of the number of colonial birds on “Lebyazhy Islands” in 1999-2018

The results of the analysis of the twenty-year dynamics of the number of colonial birds on “Lebyazhy Islands” are presented. It is shown that the process of reducing the abundance of birds in the settlements, outlined in the 1990s, led to their partial degradation. The reasons for this were: the reduction since the 1990s of the volume of water supplied through the North Crimean canal led to complete cessation in 2014 and the weakening of the regime of protection of the aquatic-territorial complex of the reserve.

МАТЕМАТИЧЕСКИЙ АНАЛИЗ ДИНАМИКИ ЧИСЛЕННОСТИ НЕКОТОРЫХ ОКОЛОВОДНЫХ ВИДОВ ПТИЦ ОСТРОВОВ СИВАША

<p>The problem of the mathematical analysis of dynamics of number of key colonial breeding waterbirds regarding to the islands of region is considered. The algorithm of an estimation of changes in number of birds is offered in scope of specific features of colonies and habitats. The data of long-term monitoring of island birds’ number have been analyzed according to proposed algorithm. On the basis of analysis results the necessity of use of the statistical indexes expressing the tendencies of changes in bird number and bird turnover is proved. For the key species of island communities the tendencies of changes in number are determined within the limits of researched region. The discussed technique of a complex estimation of breeding island bird dynamics is offered for the use at drawing up the management plans and development of nature protection actions with the purpose of conservation of bird diversity and their habitats.</p> <p><em>Key words: colonial birds, islands, dynamics of number, complex estimation</em></p> <p> </p>

Breeding success of Cacicus haemorrhous (Linnaeus) (Aves: Icteridae) in different environments in an Atlantic Forest reserve in Southeast Brazil

Several factors, including the site where the colony was established and number of active nests can influence directly or indirectly the breeding success of colonial birds. The red-rumped cacique, Cacicus haemorrhous (Linnaeus, 1766), is a passerine (Icteridae) that breeds in colonies in different environments. The objective of this study was to evaluate the breeding success of red-rumped cacique in relation to three environments (lake edge, forest and swamp) in which colonies were established in an Atlantic Forest reserve in southeast Brazil. Seven colonies from the three environments were monitored during the breeding season of 2001. Overall probability of nest survival was 40.5%. We found that colonies established in the swamp presented higher nest survival than the others and the ones in the lake edge had lower survival. Nest predation was the most important cause of nest failure, representing 46.5% of all nest losses. Other failure causes were abandonment and fall of nests, representing 6.6% and 6.1% of the losses, respectively. Red-rumped cacique had higher success breeding in colonies located in the swamp.