Brood provisioning and reproductive benefits in relation to habitat quality: a food supplementation experiment

Grüebler, Martin U.; Müller, Martina S.; Michel, Vanja T.; Perrig, Marco; Keil, Herbert; Naef‐Daenzer, Beat; Korner‐Nievergelt, Fränzi

doi:10.1016/j.anbehav.2018.05.009

Cited by 24 publications

(28 citation statements)

References 49 publications

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“…As in prey‐focused studies, artificial nests that are baited with real eggs can be employed as a tool in predator‐focused research to observe hunting behaviour by a focal predator species (Dahl & Åhlén, 2019). By altering the internal condition of individual predators, supplemental feeding treatments paired with camera traps at predator nests have been used to test the relationship between food availability and diet, parental care strategies and nestling survival in avian predators (Grüebler et al., 2018). Prey subsidies that alter the timing of food availability have revealed how phenological mismatch between predator and prey can cause a diet shift in insectivorous birds (Samplonius, Kappers, Brands, & Both, 2016).…”

Section: Experimental Applications Of Camera Traps To Predator–prey Ementioning

confidence: 99%

Zooming in on mechanistic predator–prey ecology: Integrating camera traps with experimental methods to reveal the drivers of ecological interactions

Smith

Suraci

Hunter

et al. 2020

Journal of Animal Ecology

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Camera trap technology has galvanized the study of predator–prey ecology in wild animal communities by expanding the scale and diversity of predator–prey interactions that can be analysed. While observational data from systematic camera arrays have informed inferences on the spatiotemporal outcomes of predator–prey interactions, the capacity for observational studies to identify mechanistic drivers of species interactions is limited. Experimental study designs that utilize camera traps uniquely allow for testing hypothesized mechanisms that drive predator and prey behaviour, incorporating environmental realism not possible in the laboratory while benefiting from the distinct capacity of camera traps to generate large datasets from multiple species with minimal observer interference. However, such pairings of camera traps with experimental methods remain underutilized. We review recent advances in the experimental application of camera traps to investigate fundamental mechanisms underlying predator–prey ecology and present a conceptual guide for designing experimental camera trap studies. Only 9% of camera trap studies on predator–prey ecology in our review use experimental methods, but the application of experimental approaches is increasing. To illustrate the utility of camera trap‐based experiments using a case study, we propose a study design that integrates observational and experimental techniques to test a perennial question in predator–prey ecology: how prey balance foraging and safety, as formalized by the risk allocation hypothesis. We discuss applications of camera trap‐based experiments to evaluate the diversity of anthropogenic influences on wildlife communities globally. Finally, we review challenges to conducting experimental camera trap studies. Experimental camera trap studies have already begun to play an important role in understanding the predator–prey ecology of free‐living animals, and such methods will become increasingly critical to quantifying drivers of community interactions in a rapidly changing world. We recommend increased application of experimental methods in the study of predator and prey responses to humans, synanthropic and invasive species, and other anthropogenic disturbances.

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Section: Experimental Applications Of Camera Traps To Predator–prey Ementioning

confidence: 99%

Zooming in on mechanistic predator–prey ecology: Integrating camera traps with experimental methods to reveal the drivers of ecological interactions

Smith

Suraci

Hunter

et al. 2020

Journal of Animal Ecology

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“…Second, lower availability of roosting sites in Swiss plots may limit little owls due to their key importance as a shelter from predators, disturbance and adverse weather throughout the year (Bock et al 2013 ; Grüebler et al 2014 ). Finally, the lower small rodent index in Swiss compared to German plots likely represents a direct estimate of reduced food supply for little owls in Swiss compared to German plots (Grüebler et al 2018 ).…”

Section: Discussionmentioning

confidence: 99%

“…Whereas Germany and Switzerland were broadly inhabited by little owls in the middle of the last century, populations recently declined as they did across many parts of Europe with only a few breeding pairs left in Switzerland (Schaub et al 2006 ; Thorup et al 2010 ; Habel et al 2015 ). In contrast, a vital little owl population remains in Baden-Württemberg (Bock et al 2013 ; Grüebler et al 2018 ). The little owl prefers widely open agricultural landscapes and is often associated with extensively cultivated standard fruit tree orchards and permanent meadows in Central Europe (Van Nieuwenhuyse et al 2008 ; Šálek et al 2016 ; Fattebert et al 2018 ).…”

Section: Methodsmentioning

confidence: 99%

“…The little owl prefers widely open agricultural landscapes and is often associated with extensively cultivated standard fruit tree orchards and permanent meadows in Central Europe (Van Nieuwenhuyse et al 2008 ; Šálek et al 2016 ; Fattebert et al 2018 ). Vertebrate (birds, small mammals, amphibians) and invertebrate (arthropods, earthworms) prey is mainly caught on bare ground or grassland with low vegetation (Grüebler et al 2018 ). Little owls are cavity breeders that prefer cavities with openings of at least 6 cm diameter and 20 cm depth and multiple openings for breeding (Tomé et al 2004 ; Bock et al 2013 ).…”

Section: Methodsmentioning

confidence: 99%

“…in buildings, palette stacks etc. excluding nestboxes, tree crowns and tree cavities) Binary 0; 1 Shelter (Bock et al 2013 ) Small rodent index Total predicted small rodent traces per ha: Number of runways, vole piles and holes counted on three 5 m × 1 m transects (Apolloni et al 2018 ) with one each randomly placed on meadows, field margins and orchards divided by transect area and multiplied times the cover of the respective land use (meadow, field margin, orchard) Numeric 0–11 260 Food availability (Apolloni et al 2018 ; Grüebler et al 2018 ) Covariates Number of trees Total number of trees—i.e. all trees standing freely, in groups or orchards.…”

Section: Methodsmentioning

confidence: 99%

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Political borders impact associations between habitat suitability predictions and resource availability

et al. 2020

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Context By linking species of conservation concern to their abiotic and biotic requirements, habitat suitability models (HSM) can assist targeted conservation measures. Yet, conservation measures may fail if HSM are unable to predict crucial resources. HSM are typically developed using remotely sensed land-cover classification data but not information on resources per se. Objectives While a certain land-cover class may correlate with crucial resources in the area of calibration, political boundaries can abruptly alter these associations. We investigate this potential discrepancy in a well-known study system highly relevant for farmland bird conservation. Methods We compared land cover, land-use intensity and resource availability between plots of highest habitat suitability for little owls (Athene noctua) among two neighbouring, but politically separated areas (i.e. south-western Germany vs. northern Switzerland). Results Land cover and land-use richness did not differ between German and Swiss plots. Yet there were marked differences in terms of land-use intensity and the availability of resources. Land-use intensity was significantly higher and resource availability lower in Swiss compared to German plots. Conclusions While accounting well for remotely sensed data such as land cover, HSM may fail to predict land-use intensity and resources across borders. The relationship between geodata used as proxies and ecologically relevant resources may differ according to history, policies and socio-cultural context, constraining the viability of HSM across political borders. This study emphasises the need for fine-scale resource assessments complementing landscape-scale suitability models. Conservation measures need to consider the availability of crucial resources and their socio-economic moderators to be effective.

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Reduced habitat quality increases intrinsic but not ecological costs of reproduction

Michel

Tschumi

Naef‐Daenzer

et al. 2022

Ecology and Evolution

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Although the costs of reproduction are predicted to vary with the quality of the breeding habitat thereby affecting population dynamics and life-history trade-offs, empirical evidence for this pattern remains sparse and equivocal. Costs of reproduction can operate through immediate ecological mechanisms or through delayed intrinsic mechanisms. Ignoring these separate pathways might hinder the identification of costs and the understanding of their consequences. We experimentally investigated the survival costs of reproduction for adult little owls (Athene noctua) within a gradient of habitat quality. We supplemented food to nestlings, thereby relieving the parents' effort for brood provisioning. We used radio-tracking and Bayesian multistate modeling based on marked recapture and dead recovery to estimate survival rates of adult little owls across the year as a function of food supplementation and habitat characteristics. Food supplementation to nestlings during the breeding season increased parental survival not only during the breeding season but also during the rest of the year. Thus, the low survival of parents of unfed broods likely represents both, strong ecological and strong intrinsic costs of reproduction. However, while immediate ecological costs occurred also in high-quality habitats, intrinsic costs carrying over to the post-breeding period occurred only in low-quality habitats. Our results suggest that immediate costs resulting from ecological mechanisms such as predation, are high also in territories of high habitat quality. Long-term costs resulting from intrinsic tradeoffs, however, are only paid in low-quality habitats. Consequently, differential effects of habitat quality on immediate ecological and delayed intrinsic mechanisms can mask the increase of costs of reproduction in low-quality breeding habitats. Intrinsic costs may represent an underrated mechanism of habitat quality affecting adult survival rate thereby considerably accelerating population decline in degrading habitats. This study therefore highlights the need for a long-term perspective to fully assess the costs of reproduction and the role of habitat quality in modifying these costs.

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Brood provisioning and reproductive benefits in relation to habitat quality: a food supplementation experiment

Cited by 24 publications

References 49 publications

Zooming in on mechanistic predator–prey ecology: Integrating camera traps with experimental methods to reveal the drivers of ecological interactions

Zooming in on mechanistic predator–prey ecology: Integrating camera traps with experimental methods to reveal the drivers of ecological interactions

Political borders impact associations between habitat suitability predictions and resource availability

Reduced habitat quality increases intrinsic but not ecological costs of reproduction

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