Provisioning nest material for Rooks; a potential tool for conservation management

Abstract

Active conservation measures often entail supplementing scarce resources, such as food or nesting site to high conservation value species. We hypothesized that adequate nest material in reasonable distance is a scarce resource for Rooks breeding in open grassland habitats of Hungary. Here we show that Rooks willingly utilize large quantities of provided excess nesting material, and that this procedure may alter nest composition, and increase the number of successful pairs. Our results show that while nest height remains constant, twig diameter is significantly larger, the number of twigs used per nest is presumably smaller, and that the ratio of nests with fledglings is higher in a rookery where supplementary twigs were present. Providing twigs and branches in the vicinity of rookeries may serve as an active conservation measure to increase the number of nests in a rookery, and thus the potential number of nesting possibilities for Red-footed Falcons.

Monitoring of colonies and provisioning of rooks with nest material as a potential tool for stabilizing colonies and increasing nesting opportunities in the countryside. Project report

“…The result being non-significant in the case of nest height could be caused by the smaller sample of compared nests. Horváth et al (2015) did not study the width of nests, but in contrast to our results they did not record a significant impact of the supporting activity on the height of nests. From their results it is evident that the provisioned material was used to build each nest in the supported colony, where the rooks used the twigs with a significantly larger diameter for building nests.…”

“…With a longterm perspective, in some species a gradual change in of rooks with nest material as a potential tool for stabilizing colonies and increasing nesting opportunities in the countryside. Project report preference of local or entire populations from nesting in the original, natural conditions to nesting in artificial conditions may be shown (Bartolotti 1994, Chavko et al 2014, Kotymán et al 2015. In increasing and improving the nesting conditions, emphasis is put on hollow-nesting birds or species nesting in nest boxes.…”

“…It is precisely the decline in rook colonies, along with agricultural intensification, which is described as one of the reasons for the red-footed falcon population decrease in Slovakia since the 1970's (Gúgh et al 2015). Horváth et al (2015) carried out supporting activity in SE Hungary based on nest material provision near rook colonies. The result was positively shown in the parameters of rook nests.…”

Birds use structural properties when selecting materials for different parts of their nests

“…Such sites may offer differing support from below and may be reflected in the strength and rigidity of the materials used in the nest base. Interestingly, Horváth et al (2015) showed that nests constructed high in trees by Rooks Corvus frugilegus, contain woody stems that average around 5 mm in diameter (range 2-15 mm). This may reflect the much larger body mass of this corvid [420-490 g (Dunning 2008)].…”

“…Small warblers (Sylvidae) and wagtails (Motacillidae) also rarely use woody stems in their nests (Dickinson, Locke, Goodman and Deeming, unpublished data 2018). Along with Rooks (Horváth et al 2015) other corvids, e.g. Eurasian Jays Garrulus glandarius and Carrion Crows Corvus corone, are from two to five times heavier than thrushes and also build nests largely made of woody materials (Kulczycki 1973;Ferguson-Lees et al 2011).…”