What are the important landscape components for habitat selection of the ortolan bunting Emberiza hortulana in northern limit of range?

Abstract

Ortolan buntings Emberiza hotulana have undergone one of the most severe population declines of any European farmland bird over the last thirty years. The aim of this study was to find out which habitat features, including crop characteristics, ortolan bunting prefers in Estonia in breeding areas. This study compared currently occupied and unoccupied ortolan bunting territories. Occupied areas contained significantly more tall broadleaf trees, crop types, structural elements (trees, bushes, roads, overhead power lines and buildings) and spring wheat, but also had lower crop drilling densities. Ortolan bunting territories were best described by a logistic regression model containing six variables: amount of structural point elements, length of power lines, amount of tall broadleaf trees and number of different crops had a positive effect, whereas crop density and area of autumn-sown crops had a negative effect. Based on the findings of this study, the following conservation measures can be recommended: lower crop densities; spring rather than autumn-sown crops; small-field systems containing a variety of crops; scattered scrub preserved or planted; habitat patches of permanent grasslands, hedges and tall broadleaf trees retained within the agricultural landscape.

Small things are important: the value of singular point elements for birds in agricultural landscapes

“…The term ‘point processes’ also appeared and is derived from statistical spatial modelling (Illian & Burslem, 2007). The most frequently repeated term is ‘point elements’ or ‘point objects’, referring to “habitat islands […], bedrock or stone piles, ponds, single trees” (Ihse, 1995, p. 26); “groves, trees, heaps of stones, boulders, etc.” (Mõisja et al ., 2016, p. 715); “kettle holes, isolated trees, tree groups, riparian woodlands” (Ungaro et al ., 2016, p. 400); “single tree, scattered trees, grove, boulder […], heap of stones, scattered boulders” (Elts et al ., 2015, p. 24). However, all the above studies referred only to certain selected elements, sometimes in combination with linear objects and land cover types.…”

“…S1). A solitary tree was found to be frequently used as a song post by corn buntings Miliaria calandra L. (Mason & Macdonald, 2000; Szymkowiak et al ., 2014; Altewischer et al ., 2015), ortolan buntings Emberiza hortulana L. (Fonderflick, Thévenot & Guillaume, 2005; Elts et al ., 2015), and tree pipits Anthus trivialis L. (Schwarz, Trautner & Fartmann, 2018). Trees play an important role as perches for hunting predators, e.g.…”

“…Such elements are likely important for certain rare farmland species (Fitzsimons & Michael, 2017). They may serve as a perch for birds, particularly for sit‐and‐wait predators such as the European roller (Catry et al ., 2017), or as a singing post, for example, for the ortolan bunting (Fonderflick et al ., 2005; Elts et al ., 2015) and the rock bunting Emberiza cia L. (Sánchez, Václav & Prokop, 2009). Our field observations indicate that northern wheatear Oenanthe oenanthe L. and white wagtail Motacilla alba L. in the farmlands of southern Poland prefer the vicinity of boulders and stone piles.…”

“…Some species, for example the American kestrel Falco sparverius L. (Crouch, Benson & Brennan, 2018), use electricity poles as roosting sites, particularly during the non‐breeding season. Moreover, pylons are important singing sites for some species (Mason & Macdonald, 2000; Fonderflick et al ., 2005; Elts et al ., 2015) and perching sites for birds of prey such as buzzards and common kestrels Falco tinnunculus L. (Fig. S10) as well as the European roller (Rodríguez‐Ruiz et al ., 2019).…”

“…There are a large number of publications investigating the relationships between landscape composition and bird diversity (review in Tryjanowski et al ., 2011), but few incorporate SPELs in their agricultural landscape models [but see: Szymkowiak, Skierczyński & Kuczyński (2014), Elts, Tätte & Marja (2015) and Mõisja, Uuemaa & Oja (2016)]. The occurrence and diversity of these elements are most often the result of historical, cultural and natural processes; therefore, any list of the common point elements will be region specific and may vary depending on different farming systems (Poschlod & Braun‐Reichert, 2016).…”