Feeding behavior of the great spotted woodpecker Dendrocopos major in the south of the european part of Russia (Stavropol region)

Кормовое поведение самцов и самок большого пёстрого дятла (БПД) Dendrocopus major исследовано в Ставропольском крае в период 2013-2021 гг. В целом, зарегистрировано 58 посещений дятлами 12 видов кормовых деревьев. Выявлено предпочтение БПД следующих видов деревьев: дуб (22%), граб (20%), ясень (17%). Проведено сравнение кормовых предпочтений самцов и самок БПД в различные сезоны года. В холодный период БПД предпочитали разыскивать корм на стволах и толстых ветвях деревьев, где было больше шансов обнаружить зимующих беспозвоночных. Выявлены различия в кормовых методах, используемых самцами и самками БПД. We studied the feeding behavior of males and females of the Great Spotted Woodpecker (GSW) Dendrocopos major in the Stavropol Region over 2013-2021. In general, 58 woodpeckers’ visits to 12 forage tree species were recorded. The preference of GSW of the tree species was as following: oak (22% of visits), hornbeam (20%), ash (17%). A comparison of the feeding preferences of males and females of GSW in different seasons revealed that in the cold period the GSW preferred to search for food on the trunks and thick branches of trees, where it was more likely to find wintering invertebrates.

Variation in timing of breeding of five woodpeckers in a primeval forest over 45 years: role of food, weather, and climate

Climate warming could lead to ‘mis-matching’ of birds’ breeding times with availability of their invertebrate food resources. Fluctuating spring temperatures could influence variation in the commencement of egg-laying, as well as, in phenology of their resources (e.g., tree bud burst, appearance of folivorous caterpillars). We studied timing of Dendrocopos leucotos, Dendrocoptes medius, Dendrocopos major, Dryobates minor, and Picoides tridactylus breeding in, free of direct human intervention, strictly protected fragments of Białowieża Forest (Poland) in 1975–2019. We related their onset of breeding to inter-year variation in spring weather, trees’ bud burst and timing of folivorous caterpillars’ availability. Individual species initiated breeding at dates differing by a month. In spite of intraseasonal differences in the absolute laying dates, sometimes exceeding three weeks, the sequence of laying by different species within a season was highly repeatable; D. leucotos commenced the first and P. tridactylus the last. Within a species and season, the females commenced laying synchronously; usually 50% of them begun laying ≤ 8 days of each other. All species bred earlier when spring temperatures got higher. Nestling time of D. medius and D. major broadly coincided with ‘caterpillar peaks’, while D. minor young appeared too late. All woodpeckers advanced egg-laying in Białowieża National Park over 45 years but the inter-specific sequence of laying has been retained. These could be responses to strong advance of snow disappearance and to warming of the second half of April. The early recent laying dates remained within the range of earlier recorded ones, the early springs just became more frequent. Thus, the phenological acclimatization could be achieved by plastic behavioural and physiological adjustments. Lack of data on types of food actually used and their seasonal variation hinders mechanistic understanding of how warming would affect the future food supply and breeding performance of birds.