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Spatial and temporal structure of a mesocarnivore guild in midwestern north America
Wildlife Monographs ( IF 4.4 ) Pub Date : 2015-04-27 , DOI: 10.1002/wmon.1015
Damon B. Lesmeister 1 , Clayton K. Nielsen 1 , Eric M. Schauber 1 , Eric C. Hellgren 1
Affiliation  

Carnivore guilds play a vital role in ecological communities by cascading trophic effects, energy and nutrient transfer, and stabilizing or destabilizing food webs. Consequently, the structure of carnivore guilds can be critical to ecosystem patterns. Body size is a crucial influence on intraguild interactions, because it affects access to prey resources, effectiveness in scramble competition, and vulnerability to intraguild predation. Coyotes (Canis latrans), bobcats (Lynx rufus), gray foxes (Urocyon cinereoargenteus), raccoons (Procyon lotor), red foxes (Vulpes vulpes), and striped skunks (Mephitis mephitis) occur sympatrically throughout much of North America and overlap in resource use, indicating potential for interspecific interactions. Although much is known about the autecology of the individual species separately, little is known about factors that facilitate coexistence and how interactions within this guild influence distribution, habitat use, and temporal activity of the smaller carnivores. To assess how habitat autecology and interspecific interactions affect the structure of this widespread carnivore guild, we conducted a large‐scale, non‐invasive carnivore survey using an occupancy modeling framework. We deployed remote cameras during 3‐week surveys to detect carnivores at 1,118 camera locations in 357 2.6‐km2 sections (3–4 cameras/section composing a cluster) in the 16 southernmost counties of Illinois (16,058 km2) during January–April, 2008–2010. We characterized microhabitat at each camera location and landscape‐level habitat features for each camera cluster. In a multistage approach, we used information‐theoretic methods to evaluate competing models for detection, species‐specific habitat occupancy, multispecies co‐occupancy, and multiseason (colonization and extinction) occupancy dynamics. We developed occupancy models for each species to represent hypothesized effects of anthropogenic features, prey availability, landscape complexity, and vegetative land cover. We quantified temporal activity patterns of each carnivore species based on their frequency of appearance in photographs. Further, we assessed whether smaller carnivores shifted their diel activity patterns in response to the presence of potential competitors. Of the 102,711 photographs of endothermic animals, we recorded photographs of bobcats (n = 412 photographs), coyotes (n = 1,397), gray foxes (n = 546), raccoons (n = 40,029), red foxes (n = 149), and striped skunks (n = 2,467). Bobcats were active primarily during crepuscular periods, and their activity was reduced with precipitation and higher temperatures. The probability of detecting bobcats decreased after a bobcat photograph was recorded, suggesting avoidance of remote cameras after the first encounter. Across southern Illinois, bobcat occupancy at the camera‐location and camera‐cluster scale (urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0018 = 0.24 ± 0.04, camera cluster urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0019 = 0.75 ± 0.06) was negatively influenced by anthropogenic features and infrastructure. Bobcats had high rates of colonization (urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0020 = 0.86) and low rates of extinction (urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0021 = 0.07), suggesting an expanding population, but agricultural land was less likely to be colonized. Nearly all camera clusters were occupied by coyotes (urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0022 = 0.95 ± 0.03). At the local scale, coyote occupancy (urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0023 = 0.58 ± 0.03) was higher in hardwood forest stands with open understories than in other areas. Compared to coyotes, gray foxes occupied a smaller portion of the study area (urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0024 = 0.13 ± 0.01, urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0025 = 0.29 ± 0.03) at all scales. At the scale of the camera cluster, gray fox occupancy was highest in fragmented areas with high proportions of forest, and positively related to anthropogenic features within 100% home‐range buffers. Red foxes occupied a similar proportion of the study area as gray foxes (urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0026 = 0.12 ± 0.02, urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0027 = 0.26 ± 0.04) but were more closely associated with anthropogenic features. Only anthropogenic feature models made up the 90% confidence set at all scales of analysis for red foxes. Extinction probabilities at the scale of the camera cluster were higher for both gray foxes (urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0028 = 0.57) and red foxes (urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0029 = 0.35) than their colonization rates (gray fox urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0030 = 0.16, red fox urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0031 = 0.06), suggesting both species may be declining in southern Illinois. Striped skunks occupied a large portion of the study area (urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0032 = 0.47 ± 0.01, urn:x-wiley:14381656:media:wmon1015:wmon1015-math-0033 = 0.79 ± 0.03) and were associated primarily with anthropogenic features. Raccoons were essentially ubiquitous within the study area, being photographed in 99% of camera clusters. We observed little evidence for spatial partitioning based on interspecific interactions, with the exception of the gray fox‐coyote pairs, and found that habitat preferences were more important in structuring the carnivore community. Habitat had a stronger influence on the occupancy of foxes than did the presence of bobcats. However, the level of red fox activity was negatively correlated with bobcat activity. Gray fox occupancy and the number of detections within occupied sites were reduced in camera clusters occupied by coyotes but not bobcat occupancy. Overall, gray fox occupancy was highest at camera locations with fewer hardwood and more conifer trees. However, gray foxes were more likely to occupy camera locations in hardwood stands than conifer stands if coyotes were also present indicating that hardwood stands may enhance gray fox‐coyote coexistence. The 2 fox species appeared to co‐occur with each other at the local scale more frequently than expected based on their individual selection of habitat. Similarly, occupancy of camera location by red foxes was higher when coyotes were present. These positive spatial associations among canids may be a response to locally high prey abundance or unmeasured habitat variables. Activity levels of raccoons, bobcats, and coyotes were all positively correlated. Overall, our co‐ occurrence and activity models indicate competitor‐driven adjustments in space use among members of a carnivore community might be the exception rather than the norm. Nevertheless, although our results indicate that gray foxes and red foxes currently coexist with bobcats and coyotes, their distribution appears to be contracting on our study area. Coexistence of foxes with larger carnivores may be enhanced by temporal partitioning of activity and by habitat features that reduce vulnerability of intraguild predation. For instance, hardwood stands may contain trees with structure that enhances tree‐climbing by gray foxes, a behavior that probably facilitates coexistence with coyotes. Efforts to enhance gray fox populations would likely benefit from increasing the amount of mature oak‐hickory forest. Additionally, the varying results from different scales of analyses underscore the importance of considering multiple spatial scales in carnivore community studies. © 2015 The Wildlife Society.

中文翻译:

北美中西部食肉动物行会的时空结构

食肉动物行会通过级联营养作用,能量和养分转移以及稳定或破坏食物网来在生态社区中发挥重要作用。因此,食肉动物行会的结构对于生态系统模式可能至关重要。体型是对公会内部互动的关键影响,因为它会影响猎物资源的获取,争夺竞争的有效性以及公会内部捕食的脆弱性。土狼(Canis latrans),山猫(Lynx rufus),灰狐狸(Urocyon cinereoargenteus),浣熊(Procyon lotor),红狐狸(Vulpes vulpes)和条纹臭鼬(Mephitis mephitis))在整个北美大部分地区都同伴发生,并且资源使用重叠,表明种间相互作用的潜力。尽管对各个物种的自律学知之甚少,但对促进共存的因素以及该行会中的相互作用如何影响较小食肉动物的分布,栖息地使用和时间活动知之甚少。为了评估栖息地自律学和种间相互作用如何影响这个广泛的食肉动物行会的结构,我们使用占用模型框架进行了一次大规模的非侵入性食肉动物调查。我们在为期3周的调查中部署了远程摄像头,以在357个2.6 km 2中的1118个摄像头位置检测食肉动物伊利诺伊州最南端的16个县(16,058 km 2)期间,即2008年1月至4月。我们对每个相机位置的微栖息地和每个相机集群的景观水平栖息地特征进行了表征。在多阶段方法中,我们使用信息理论方法来评估竞争模型,以进行检测,特定物种的栖息地占用,多物种共同占用以及多季节(殖民化和灭绝)占用动态。我们为每个物种开发了占用模型,以代表人为特征,猎物可利用性,景观复杂性和植被覆盖的假设效应。我们根据每个食肉动物物种在照片中出现的频率对它们的时间活动模式进行了量化。此外,我们评估了较小的食肉动物是否响应潜在竞争者的存在而改变了他们的diel活动模式。在102个中,n  = 412张照片),郊狼(n  = 1,397),灰狐狸(n  = 546),浣熊(n  = 40,029),红狐狸(n  = 149)和条纹臭鼬(n  = 2,467)。山猫主要在黄昏时期活动,随着降水和温度升高,山猫的活动减弱。记录山猫照片后,检测到山猫的可能性降低,这表明在初次相遇后避免使用远程相机。在整个伊利诺伊州南部,山猫在相机位置和相机集群规模(缸:x-wiley:14381656:media:wmon1015:wmon1015-math-0018 = 0.24±0.04,相机集群:x-wiley:14381656:media:wmon1015:wmon1015-math-0019 = 0.75±0.06)上的占用受到人为特征和基础设施的负面影响。山猫的殖民率很高(缸:x-wiley:14381656:media:wmon1015:wmon1015-math-0020 = 0.86)和低灭绝率(骨灰盒:x-wiley:14381656:media:wmon1015:wmon1015-math-0021 = 0.07),表明人口正在增加,但农业土地被殖民的可能性较小。几乎所有的相机群都被土狼占据(骨灰盒:x-wiley:14381656:media:wmon1015:wmon1015-math-0022 = 0.95±0.03)。在当地范围内,骨灰盒:x-wiley:14381656:media:wmon1015:wmon1015-math-0023 林下开放的硬木林地的土狼占用率(= 0.58±0.03)高于其他地区。与土狼相比,灰狐 在所有尺度下都占据了研究区域的较小部分(缸:x-wiley:14381656:media:wmon1015:wmon1015-math-0024 = 0.13±0.01,:x-wiley:14381656:media:wmon1015:wmon1015-math-0025= 0.29±0.03)。在相机集群的规模上,灰狐的占用率最高的是森林比例高的零散区域,并且与100%家庭范围缓冲区内的人为特征正相关。赤狐占据研究区域的比例与灰狐类似(骨灰盒:x-wiley:14381656:media:wmon1015:wmon1015-math-0026 = 0.12±0.02,骨灰盒:x-wiley:14381656:media:wmon1015:wmon1015-math-0027 = 0.26±0.04),但与人为特征密切相关。在所有分析规模的赤狐中,只有人为特征模型构成了90%的置信度。灰狐狸(骨灰盒:x-wiley:14381656:media:wmon1015:wmon1015-math-0028 = 0.57)和红狐狸(骨灰盒:x-wiley:14381656:media:wmon1015:wmon1015-math-0029 = 0.35)在相机群尺度上的灭绝概率均高于其定居率(灰狐狸缸:x-wiley:14381656:media:wmon1015:wmon1015-math-0030 = 0.16,赤狐狐狸缸:x-wiley:14381656:media:wmon1015:wmon1015-math-0031 = 0.06),这表明南部的两个物种可能都在减少伊利诺伊州。条纹臭鼬占据了研究区域的大部分(缸:x-wiley:14381656:media:wmon1015:wmon1015-math-0032 = 0.47±0.01,骨灰盒:x-wiley:14381656:media:wmon1015:wmon1015-math-0033 = 0.79±0.03),并且主要与人为特征相关。浣熊在研究区域内无处不在,在99%的相机组中被拍照。除了灰狐狸-土狼对以外,我们几乎没有观察到基于种间相互作用进行空间划分的证据,并且发现栖息地的偏好在构造食肉动物群落方面更为重要。生境对山猫的影响要强于山猫。但是,赤狐活动水平与山猫活动呈负相关。在土狼占据的相机集群中,灰狐的占有率和所占位置内的检测数量均减少了,但山猫的占有率却没有降低。总体而言,灰狐在相机位置的占有率最高,硬木较少,针叶树较多。然而,如果还存在土狼,则灰狐狸比针叶树种更可能占据硬木林分的照相机位置,这表明硬木林分可以增强灰狐狸-土狼的共存性。根据它们对栖息地的个体选择,这两种狐狸在当地规模上的共生频率似乎比预期的高。同样,当土狼出现时,赤狐对照相机位置的占用也较高。犬科动物之间的这些积极的空间联系可能是对当地高猎物丰富度或无法测量的栖息地变量的反应。浣熊,山猫和土狼的活动水平均呈正相关。总体而言,我们的共现和活动模型表明,食肉动物群落成员之间竞争者驱动的空间使用调整可能是例外,而不是常规。不过,尽管我们的结果表明,灰狐和红狐目前与山猫和土狼共存,但它们的分布似乎在我们的研究区域收缩。活动的时间划分和减少行会内捕食的脆弱性的栖息地特征可能会增强狐狸与大型食肉动物的共存。例如,硬木林分可能包含树木,其结构会增强灰狐狸的爬树行为,这种行为可能有助于与土狼共存。增加成熟的橡木山核桃森林的数量可能会增加灰狐种群的数量。此外,来自不同分析规模的不同结果强调了在食肉动物群落研究中考虑多个空间尺度的重要性。©2015野生动物协会。
更新日期:2015-04-27
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