Abstract
BackgroundSelecting high-quality habitat and the optimal time to reproduce can increase individual fitness and is a strong evolutionary factor shaping animal populations. However, few studies have investigated the interplay between land cover heterogeneity, limitation in food resources, individual quality and spatial variation in fitness parameters. Here, we explore how individuals of different quality respond to possible mismatches between a cue for prey availability (land cover heterogeneity) and the actual fluctuating prey abundance.ResultsWe analyse timing of breeding and reproductive success in a migratory population of Eurasian kestrels (Falco tinnunculus) breeding in nest-boxes, over a full three-year abundance cycle of main prey (voles), and consider several components of individual quality, including body condition, blood parasite infection, and genetic diversity (n = 448 adults) that act on different time scales. Older individuals, and kestrel parents in higher body condition started egg-laying earlier than younger birds and those in lower body condition. Additionally, egg-laying was initiated earlier during the increase and decrease phases (2011 and 2012) than during the low phase of the vole cycle (2013). Nestling survival (ratio of eggs that fledged successfully) was higher in early nests and in heterogeneous landscapes (i.e., mosaic of different habitat types), which was evident during the increase and decrease phases of the vole cycle, but not during the low vole year.ConclusionsWe found a strong positive effect of landscape heterogeneity on nestling survival, but only when voles were relatively abundant, whereas a difference in the timing of breeding related to territory landscape heterogeneity was not evident. Therefore, landscape heterogeneity appeared as the main driver of high reproductive performance under favourable food conditions. Our results show that landscape homogenization linked to agricultural intensification disrupts the expected positive effect of vole abundance on reproductive success of kestrels.
Highlights
Selecting high-quality habitat and the optimal time to reproduce can increase individual fitness and is a strong evolutionary factor shaping animal populations
Individual quality We quantified indices for individual quality that act on different time scales: i) body condition; ii) blood parasite infection, iii) genetic diversity; and iv) age as a proxy for breeding experience
Early arriving kestrels that are older and/or in higher body condition started egg-laying earlier, but did not show a clear habitat preference for either homogeneous agricultural landscapes or more heterogeneous landscapes. Kestrels breeding in the latter had higher nestling survival than their con-specifics, an effect that was visible only during the increase and decrease phases of the vole cycle
Summary
Selecting high-quality habitat and the optimal time to reproduce can increase individual fitness and is a strong evolutionary factor shaping animal populations. Selecting the right time and place to reproduce is an essential decision for animals It will affect their reproductive output and long-term survival, and as a result what we refer to as individual fitness [1, 2]. Large-scale changes in land-cover can have detrimental effects on species either through habitat loss and fragmentation [9, 10], or in a more devious manner, by uncoupling cues used to select a suitable habitat, and the true value of this habitat [11] This type of uncoupling has been shown in many ground-nesting birds that persist to breed in intensive farmlands because they are lured by cues that used to be appropriate in pristine open habitats [2]. Identifying the existence of cue mismatches and unravelling the mechanisms behind them is necessary to fully understand and predict the impacts of land-use changes on population dynamics
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