Linking landscape composition to predator-specific nest predation requires examining multiple landscape scales

• Published in: The Journal of applied ecology Vol. 55; no. 4; pp. 2082 - 2092
• Main Authors: Chiavacci, Scott J., Benson, Thomas J., Ward, Michael P.
• Format: Journal Article
• Language: English
• Published: Oxford John Wiley & Sons Ltd 01.07.2018; Blackwell Publishing Ltd
• Subjects: Adaptive management; Birds; Composition; Decision making; Dependence; Ecological effects; Land cover; Landscape; landscape composition; landscape scale; Management; nest camera; nest predation; nest survival; Nesting; Nests; Pantherophis obsoletus; Pantherophis vulpinus; Predation; Predators; Procyon lotor; Reproductive failure; scale‐dependence; shrub‐nesting bird; Snakes; Species; Wildlife monitoring
• ISSN: 0021-8901; 1365-2664
• DOI: 10.1111/1365-2664.13090

1. Landscape composition around bird nests can strongly influence nest predation, a major cause of reproductive failure for many species. Understanding this relationship may improve the effectiveness of management actions aimed at reducing predation. Despite attempts to link landscape composition to nest predation, consistent patterns have proven elusive, likely because studies often examine only one landscape scale, thereby overlooking scale-specific interactions between predators and landscape features. 2. To demonstrate the value of incorporating scale-dependence when connecting nest predation to landscape composition, we identified predators and analysed predator-specific patterns among land cover types at four scales (200 m, 500 m, 1 km, 2.5 km). We video monitored 468 nests of 22 shrub-nesting bird species, documented 212 predation events, and modelled relationships between landscape composition and predation by seven common predators. 3. The direction and strength of predator-specific relationships varied among land cover types and scales. No single scale best predicted predation by all predators, though effects appeared to be stronger at larger scales. Two ecologically similar predators (fox snakes [Pantherophis vulpinus] and black ratsnakes [P. obsoletus]) showed contrasting relationships with different land cover types and one commonly cited predator (raccoon [Procyon lotor]) showed positive and negative links to developed cover across scales. 4. Synthesis and applications. Our results illustrate that elucidating the complex relationships between different nest predator species and the landscape composition surrounding nests requires the incorporation of scale-dependence. Although such an undertaking may involve intensive nest monitoring to identify predators, it can provide managers with a more complete understanding of the linkages between predation and the landscape surrounding nests. With this knowledge, managers could employ structured decision making in an adaptive management framework to identify optimal strategies that address nest predation and allow them to confront potentially unexpected changes in predation patterns following management actions. Ultimately, by acknowledging that predator species differ in their relationships with landscape composition among different landscape scales, and incorporating this fact into future research, we can improve our ability to focus management on the habitats and scales most likely to impact predators of interest.