Does breeding success lead meadow passerines to select late mown fields?

Abstract

Agri-environment schemes usually assume that suitable management in patches of grassland habitat may benefit bird populations in improving the overall demographic balance. In this study, we investigate the hypothesis that nesting site fidelity after previous breeding success might lead meadow birds to select late mown fields where the risk of breeding failure is lower. It was carried out in 4 study areas of the Mézenc volcanic massif (south-east of France) within the altitude range 1,150-1,350 m. Meadow passerine territories were defined by the territory mapping method, and reproductive success in Whinchat Saxicola rubetra territories was assessed by the observation of prey carrying and juveniles just leaving nests. A comparison of models led us to consider that territorial birds selected hay fields under the influence of grass structure rather than through a theoretical successful experience of late mowing. Higher territory density was observed in fields with dense grass cover C50 cm which were usually more fertilized ([75 kg ha -1 nitrogen per year) and mown earlier. In 3 study sites, however, the rate of nesting failure due to mowing was lower than expected under the hypothesis of randomly distributed nesting sites, suggesting that the risk was not ignored by territorial birds. Within each study site, we also observed higher invertebrate abundance during the chick feeding period in fields with high bird territory density. ZusammenfassungWählen Singvögel des Offenlandes aufgrund von erhöhtem Bruterfolg spät gemähte Felder? Agrar-Umweltprogramme gehen normalerweise von der Annahme aus, dass Vogelpopulationen von geeigneten Managementmaßnahmen auf fleckenarteigen Teilflächen des Graslands profitieren könnten, weil durch sie die demographische Bilanz insgesamt verbessert würde. In der vorliegenden Studie bearbeiten wir die Hypothese, dass Nestortstreue nach vorherigem Bruterfolg Wiesenbrüter dazu führt, spät gemähte Felder auszuwählen, auf denen das Brutverlust-Risiko geringer ist. Die Studie wurde auf vier Teilflächen des Mézenc Vulkanmassivs (Südost-Frankreich) in Höhenlagen von 1,150-1,350 m durchgeführt. Die Brutreviere von wiesenbrütenden Singvögeln wurden mit Hilfe einer Revierkartierungsmethode erfasst, und der Reproduktionserfolg in Revieren des Braunkehlchens Saxicola rubetra durch Beobachtung Futter tragender Altvögel und gerade flügger Jungvögel bestimmt. Ein Vergleich von Modellen führte uns zu dem Schluss, dass territoriale Vögel Wiesen für die Heuernte eher unter dem Einfluss der Vegetationsstruktur auswähl-ten, als unter dem Aspekt einer theoretisch erfolgreichen Bruterfahrung durch späte Mahd. Eine höhere Revierdichte konnte vor allem in Feldern mit dichter Grasbedeckung C50 cm beobachtet werden, die normalerweise besser gedüngt waren ([75 kg ha -1 Stickstoff pro Jahr) und früher gemäht wurden. In drei Untersuchungsflächen war die Brutverlustrate durch Mähen allerdings niedriger, als Communicated by F. Bairlein.

Breeding success affects site fidelity in a WhinchatSaxicola rubetrapopulation in abandoned fields

“…First, the majority of Whinchats in Western Europe breed in agricultural grasslands -wet meadows, hayfields, and pastures (Bastian et al 1997). Accordingly, agriculture intensification appears to be the main factor affecting their breeding success, mainly due to early mowing of grasslands and the associated nest destruction (Müller et al 2005, Grüebler et al 2008, Broyer 2009, Broyer et al 2012, Calladine & Bray 2012, Fischer et al 2013. Secondly, the existing studies on demographic parameters of Whinchats in Western Europe were carried out in declining populations with low breeding densities (Müller et al 2005, Grüebler et al 2008.…”

Habitat management effects on Prealpine grassland bird communities

“…However, further studies investigating breeding success are needed to rule out that the association with mown areas did not arise as a consequence of maladaptive habitat selection (e.g. Chamberlain & Crick 1999;Müller et al 2005;Gilroy et al 2011;Broyer et al 2012). Important management indications emerge from our findings.…”

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

“…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).…”

“…The probability is therefore weak that reproductive outputs were strongly enhanced by intermittent mowing. Moreover, natal philopatry in meadow passerines seems to be usually low in Russia (Shitikov et al, 2011) and grass structure is a prevailing condition in habitat selection by nesting Whinchats (Broyer et al, 2012). In the Whinchat only, hatching success seemed to be negatively influenced by passerine territory density.…”