Wing-size related habitat choice of Great Reed Warbler females: the role of habitat quality and management

Abstract

Intersexual differences in habitat choice can arise if males and females differ in morphology, physiology, niche partitioning, or resource use, and can be influenced by variation in habitat structure, quality, and management. To better understand such intersexual differences, we studied habitat choice in female Great Reed Warblers (Acrocephalus arundinaceus), a long-distance migrant flagship species of lowland Palearctic reed (Phragmites australis) habitats. We compared wing length, a widely used proxy for individual quality in passerines, of females nesting in six types of differently managed reed habitats. Our dataset on 391 females nesting in 32 sites over 10 years showed that wing length was significantly greater in mining ponds and medium-sized canals than on large canals. Wing length was negatively related to water level fluctuation and females showed strong philopatry to the habitat type in which they were first captured. In comparison to our previous study on male habitat choice, this study found differences in habitat choice between the sexes. Although long-winged individuals in both sexes preferred habitats with stable water and avoided small canals, longer-winged males preferred large canals with little or no management, whereas long-winged females preferred medium-sized canals with some management. Although these results provide some support for intersexual niche segregation, it is also possible that long-winged females avoid large canals, in which nest parasitism by Cuckoos (Cuculus canorus) is frequent, and/or prefer managed, sparse reed beds with better maneuverability for foraging. Our studies suggest that males may primarily choose habitats with abundant old reed and singing perches, whereas females are less sensitive to environmental variation and may choose nest sites based on male quality or territory quality. For conservation, our studies imply that the maintenance of stable water levels, a low intensity of management and the elimination of Cuckoo perches are likely to benefit both long-winged males and females. Sélection d'habitat lié à la longueur de l'aile chez les Rousserolles turdoïdes femelles : le rôle de la qualité de l'habitat et de l'aménagement RÉSUMÉ. Des différences dans la sélection d'habitat liées au sexe peuvent s'observer si les mâles et les femelles diffèrent en termes de morphologie, de physiologie, de différenciation de niche ou d'utilisation des ressources, et peuvent être influencées par la variation de structure, de qualité et de l'aménagement de l'habitat. Pour mieux comprendre ce type de différences intersexuelles, nous avons étudié la sélection d'habitat chez la femelle Rousserolle turdoïde (Acrocephalus arundinaceus), espèce-phare migratrice de longue distance occupant des milieux paléarctiques de basses terres dominées par le roseau (Phragmites australis). Nous avons comparé la longueur de l'aile, un indicateur très utilisé pour attester de la qualité individuelle des passereaux, de femelles nichant dans six types de milieux de roseaux aménagés de façon différente....

Quintuple parasitism of a great reed warbler nest by common cuckoos

“…All common cuckoo eggs are marked with an asterisk The narrow reed beds along the irrigation channels run parallelly to lines of tall trees from where cuckoos can eavesdrop on hosts (Marton et al, 2019), and are the preferred breeding sites of great reed warblers (Báldi, 1999;Báldi & Kisbenedek, 1999). Early arriving, high-quality great reed warbler males occupy these habitats prefer these "edge-habitats" at the detriment of their own breeding success, as previous studies have shown that these irrigation channels have high parasitism rates and act as ecological traps for the hosts Mérő et al, , 2020. Therefore, it is likely that this conjuncture of high nesting host density, a high probability for the parasite to find host nests in the narrow reed bed, high density of parasites, and the occasional improper management of the reed (Mérő, Lontay, et al, 2015;Mérő et al, 2018) can facilitate the appearance of multiple brood parasitism.…”

The role of reed management and habitat quality on brood parasitism and chick survival of the brood parasitic Common Cuckoo

“…These shallow canals usually dry out already by late May or early June. For more information about the study region and reed habitats, see Mérő et al ( 2016 , 2018 , 2020 ).…”

“…This decline, however, can be reverted by applying conservation measures in the breeding grounds to improve nesting habitats and food availability (Denerley et al, 2019 ; Hewson et al, 2016 ). Both nesting habitat quality and amount of food resources can be influenced by habitat management (e.g., Battisti et al, 2020 ; Lindstrom et al, 2020 ; Mérő et al, 2020 ). Habitat management can help in creating habitat fragments with vegetation patches of different ages (e.g., reed habitats), thus influencing the breeding density of potential Cuckoo hosts (Battisti et al, 2020 ; Mortelliti et al, 2012 ; Sozio et al, 2013 ).…”

Reuse of nests in the Great Reed Warbler Acrocephalus arundinaceus: A behavior to save time and energy and to deter nest parasites?

“…Our study area is located in the region of Sombor, in the north‐west Serbia, in an intensive agricultural area with a moderate continental climate. In our field studies, we monitor Great Reed Warblers on mining ponds, marshes, and different types and sizes of canals (Mérő et al, 2020). Here, we report on observations on three extreme cases of nest reuse in the Great Reed Warbler; two observed on a mining pond (hereafter MP; N 45.8988°, E 19.0798°) near the village of Gakovo, and one observed on the large canal Veliki Bački Canal, at the former Fernbach farm near the town of Sombor (hereafter VBC; N 45.7332°, E 19.1798°).…”

“…During the first half of June, we recorded en mass roosting of young Starlings Sturnus vulgaris (up to c. 1000 individuals), in the reed patches with presence of water (Figure 1a,b). Methods of nest surveys, nest checks and measurement of water depth taken during every visit, nest height and reed density is described in detail in Mérő, Žuljević, Varga, and Lengyel (2016); Mérő et al (2020). Eggs were numbered with a permanent felt pen immediately after finding them in the nest during every nest checks.…”