Quantifying risk and resource use for a large carnivore in an expanding urban–wildland interface

Journal of Applied Ecology, Год журнала: 2015, Номер 53(2), С. 371 - 378

Опубликована: Окт. 28, 2015

Summary Large carnivores, though globally threatened, are increasingly using developed landscapes. However, most of our knowledge their ecology is derived from studies in wildland systems; thus, for effective conservation and management, there a need to understand behavioural plasticity risk mortality more We examined cougar Puma concolor foraging survival an expanding urban–wildland system Colorado 2007 2013. For GPS ‐collared individuals, we related diet ( n = 41; isotopic analysis) age–sex class fine‐scale space use, with regard levels habitat development. also how development impacted 49), hazards models records cougar–human conflict. Cougars obtained 63–82% assimilated biomass native herbivores, adult females consistently showed higher use herbivores than other classes. Individuals the highly areas approximately 20% alternative prey (synanthropic wildlife domestic species) those least areas. Overall, was males. Yet, substantially increased mortality; every 10% increase housing density, by 6·5%, regardless sex. Synthesis applications . flexibility diet, taking advantage human‐associated items, but had high rates mortality, suggesting that human tolerance, rather adaptability, may be limiting factor range expansion large carnivores. Thus, carnivore will not only depend upon adequate resources, potential conflict resulting depredation synanthropic animals.

Язык: Английский

---

Does Urbanization Affect Predation of Bird Nests? A Meta-Analysis

Frontiers in Ecology and Evolution, Год журнала: 2017, Номер 5

Опубликована: Апрель 11, 2017

Urbanization can affect interspecific interactions such as predator-prey relationships. Several hypotheses have been postulated to predict how predation on bird nests changes along urbanization gradients; some increased and others decreased pressures in urban compared rural habitats. Using a formal meta-analytical approach, we carried out systematic literature review test whether natural artificial or with urbanization. We found that the effect was highly heterogeneous among studies, due contrasting results between studies used those nests. For nests, survival rate tended decrease increasing urbanization, higher more urbanized study sites. increase level of The latter finding supports predictions 'urban habitats predation-safe zones' nest predator paradox' hypotheses, but may be confounded by many not distinguishing other sources mortality. None considered methodological ecological variables explained variation robust way. discrepancy differences experimental design (e.g., cavity commonly studied studies), intrinsic two types lack parental defense nests), sampling bias. conclude direction relationship is likely depend methodology study. Therefore, from using different methodologies, particularly should generalized caution avoid over-interpretations.

Язык: Английский

---

The ecological impacts of commensal species: black rats, Rattus rattus, at the urban–bushland interface

Wildlife Research, Год журнала: 2015, Номер 42(2), С. 86 - 86

Опубликована: Янв. 1, 2015

Exotic species have had devastating impacts worldwide and are a major threat to native wildlife. Human commensal (hereafter commensals) special class of exotic that live largely off the resources associated with human activity. The encroachment commensals from an urban area into surrounding bushland has been frequently overlooked as important component impacts, even though human-commensals common many regions globally. In this review, we present theoretical empirical evidence for processes outcomes occurring when encroach bushland. Specifically ask when, how why bushland, what determines whether they establish, ecological consequences. We focus on black rat, Rattus rattus, arguably archetypal cosmopolitan distribution greatest potential damage all rodents. expect outline apply other more broadly. argue in fact natives milieu only become alien peri-urban propose mechanisms will be different those other, non-commensal because areas act dispersal hubs overcome barriers invasion face. suggest resource supplementation by creates great promoting encroachment, well impact. However, biotic abiotic still relevant commensals, highlighting need maintain integrity ecosystems wildlife populations edges so prevent incursion. examine rats affect via three fundamental mechanisms, namely, predation, disease transfer competition resources, also consider their possible positive acting functional replacements lost natives. conclude review research priorities future directions essential progressing our understanding ecology species.

Язык: Английский

---

Effects of urbanization on direct and indirect interactions in a tri‐trophic system

Ecological Applications, Год журнала: 2016, Номер 26(3), С. 664 - 675

Опубликована: Апрель 1, 2016

While effects of urbanization on species assemblages are receiving increasing attention, ecological interactions remain largely unexplored. We investigated how influences the strength direct and indirect trophic in a tri- system. In field experiment including five cities nearby farmed areas, we used potted Vicia faba plants manipulated presence Megoura viciae aphids that naturally occurring aphid predators. When predators could access aphids, they reduced their abundance less urban than agricultural ecosystem. Compared to without predator access, with was 2.58 times lower 5.27 areas. This indicates limited top-down control by both ecosystems, plant biomass negatively affected herbivores positively predators, but positive effect weaker cities. aphid-infested were 1.89 heavier 2.12 Surprisingly, differences between ecosystems regarding not explained differentially strong herbivore suppression. Instead, environment per se, thereby mitigating scope effect. Our results show can influence through biotic forces growth. order understand affects biodiversity ecosystem functioning, it is fundamental only consider assemblages, also interactions.

Язык: Английский

---

Stability in prey abundance may buffer Black Sparrowhawks Accipiter melanoleucus from health impacts of urbanization

Ibis, Год журнала: 2016, Номер 159(1), С. 38 - 54

Опубликована: Окт. 14, 2016

As the global trend towards urbanization continues, need to understand its impact on wildlife grows. Species may have different levels of tolerance urban disturbance; some even appear thrive in areas and use human‐subsidized resources. However, physiological costs trade‐offs faced by urban‐dwelling species are still poorly understood. We assess evidence for a negative Black Sparrowhawk Accipiter melanoleucus , raptor that recently colonized Cape Town, South Africa, explore potential mechanisms behind any such effect. predicted birds more urbanized be poorer health this partially driven differences prey quantity quality along an habitat gradient. The nestlings was evaluated through measures their stress (heterophil/lymphocyte ratio), body condition blood parasite infection (infection risk intensity Haemoproteus Leucocytozoon ). Diet composition determined analysis remains collected around nests, abundance point counts types. could find no effects nestling health, with significant relationships heterophil/lymphocyte ratio, condition, or . Risk did, however, decline increasing cover, perhaps because contain less blackflies, vectors parasite, which require moving fresh water. found change diet breadth cover. Although were abundant certain types, all types contained ample Sparrowhawks. widespread food resources resulting lack nutritional explain why Sparrowhawks seemingly free impacts expected arise from urbanization. These findings success Town suggest urban‐dwelling, bird‐eating raptors cities override due disturbance other sources stress.

Язык: Английский

---