Mowing management and density dependence in meadow passerine hatching success

Abstract

Capsule Improving habitat quality through late or intermittent mowing may increase passerine population density without reducing reproductive success. Aim To describe the relationship between passerine territory density (TD) and Whinchat Saxicola rubetra and Yellow Wagtail Motacilla flava hatching success, under different management regimes. Methods TD was defined by the Territory Mapping method in nine sites selected in five French flood plains, in four intermittently mown meadows in Russia and in four additional French sites where mowing was partially postponed. Hatching success was assessed by the observation of prey carrying. Generalized Linear Mixed Models were used to analyse the influence on hatching rates of mowing management, early mowing and TD. Linear Mixed Models were used to study the effect of mowing management on TD. Results In French early mown meadows, TD affected reproductive success. Higher hatching rates and TD were observed in Russia. Similar results in French study sites with postponed mowing confirmed the influence of mowing management on carrying capacity. Conclusion In west-European grassland systems, late or intermittently mown patches within or at the edge of meadow areas, with potentially improved invertebrate-prey availability, should help to sustain bird demography and improve the efficiency of current conservation programmes.

How to sustain meadow passerine populations in Europe through alternative mowing management

“…But the obtained increase in population density may theoretically lead to higher competition between neighboring pairs, with negative consequences on nesting success (Broyer, 2011). However, in a previous work in late mown French grasslands, we observed high hatching success, similar to that recorded in extensively managed grasslands in Russia, whereas passerine territory density was high (Broyer et al, 2014). This study describes the variation in meadow passerine density and hatching rate after implementation of alternative mowing management in controlled experiments: either grass cutting postponement until after 15 July in the Saône Valley (eastern France), or temporary interruption of mowing in the Moskva Valley (Central Russia).…”

“…The null model (*) includes only the intercept. (Saône Valley, 2010-2014 the use of late mown areas remained stable throughout the experiment, as if this species was not attracted by late mown grassland areas and was characterized by a weak natal philopatry at the level of study sites (Shitikov et al, 2011;Broyer et al, 2012). However, increasing Whinchat population in the Saône Valley after AES implementation in the 1990s seems to indicate the existence of natal philopatry at the regional scale (Broyer, 2011).…”

“…Each study site in both countries was made up of hay meadows only. At the level of each valley, similar conditions in all replicates, experimental and control grasslands: dominant flora, management prior to the experiments, surrounding landscape with open hay-meadows (for details, see Broyer et al, 2014), enabled us to avoid confounding effects.…”

Nestling diet optimization and condition in relation to prey attributes and breeding patch size in a patch-resident insectivorous passerine: an optimal continuum and habitat constraints

“…in the Scottish Highlands Whinchats preferred warmer south-facing hillsides (Calladine and Bray 2012)]. One can assume that the major threats to Whinchats and other birds breeding in grasslands nowadays are the direct mortality/ nest losses of birds due to mowing and the intensification of agricultural management as a result of the encroachment of tall grass species resulting from nitrogen deposition and acidification, which diminish habitat suitability and reduce prey accessibility Broyer et al 2014;Fischer et al 2013;van Oosten et al 2014).…”

“…The primary breeding habitat of Whinchat used to be invertebrate-rich grasslands, especially those lying within traditionally managed agricultural landscapes, where the abundance and diversity of arthropod prey were higher than in intensively managed grasslands (Oppermann 1999;Bastian and Bastian 1996;Britschgi et al 2006;Broyer et al 2012;Strebel et al 2015). The recent population decline of grassland birds, including the Whinchat, has been ascribed mainly to nest losses/female mortality resulting from more intensive agriculture practices, primarily earlier and more frequent mowing (Grüebler et al 2008(Grüebler et al , 2012, deteriorating food/foraging conditions in semi-natural grasslands/meadows and the loss of marginal habitats (Müller et al 2005;Britschgi et al 2006;Perlut et al 2008;Broyer 2009;Broyer et al 2012Broyer et al , 2014Henderson et al 2014;Strebel et al 2015). A very recent investigation has found evidence that mortality in Whinchats occurs primarily outside the wintering period, i.e.…”