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Browsing by Author "Black, Kathleen M."

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    Epidemiology of sarcoptic mange in a geographically constrained insular red fox population
    Wails, Christy N.; Helmke, Claire C.; Black, Kathleen M.; Ramirez-Barrios, Roger; Karpanty, Sarah M.; Catlin, Daniel H.; Fraser, James D. (2024-06-06)
    Background: Sarcoptic mange is a skin disease caused by the contagious ectoparasite Sarcoptes scabiei, capable of suppressing and extirpating wild canid populations. Starting in 2015, we observed a multi-year epizootic of sarcoptic mange affecting a red fox (Vulpes vulpes) population on Fire Island, NY, USA. We explored the ecological factors that contributed to the spread of sarcoptic mange and characterized the epizootic in a landscape where red foxes are geographically constrained. Methods: We tested for the presence of S. scabiei DNA in skin samples collected from deceased red foxes with lesions visibly consistent with sarcoptic mange disease. We deployed 96–100 remote trail camera stations each year to capture red fox occurrences and used generalized linear mixed-effects models to assess the affects of red fox ecology, human and other wildlife activity, and island geography on the frequency of detecting diseased red foxes. We rated the extent of visual lesions in diseased individuals and mapped the severity and variability of the sarcoptic mange disease. Results: Skin samples that we analyzed demonstrated 99.8% similarity to S. scabiei sequences in GenBank. Our top-ranked model (weight = 0.94) showed that diseased red foxes were detected more frequently close to roadways, close to territories of other diseased red foxes, away from human shelters, and in areas with more mammal activity. There was no evidence that detection rates in humans and their dogs or distance to the nearest red fox den explained the detection rates of diseased red foxes. Although detected infrequently, we observed the most severe signs of sarcoptic mange at the periphery of residential villages. The spread of visual signs of the disease was approximately 7.3 ha/week in 2015 and 12.1 ha/week in 2017. Conclusions: We quantified two separate outbreaks of sarcoptic mange disease that occurred > 40 km apart and were separated by a year. Sarcoptic mange revealed an unfettered spread across the red fox population. The transmission of S. scabiei mites in this system was likely driven by red fox behaviors and contact between individuals, in line with previous studies. Sarcoptic mange is likely an important contributor to red fox population dynamics within barrier island systems.
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    Using GPS location data to assess red fox responses to predator exclosure setup and hatching at shorebird nests
    Black, Kathleen M.; Karpanty, Sarah M.; Robinson, Samantha G.; Bellman, Henrietta A.; Walker, Katie M.; Catlin, Daniel H.; Fraser, James D. (Wiley, 2023-01)
    Wire cages (i.e., predator exclosures) are frequently used to protect shorebird nests from predation. While exclosed nests often have higher survival than unexclosed nests, concerns exist over whether the conspicuous structures might draw attention of predators, potentially increasing risks to adults and newly-hatched chicks. We present a new approach to investigating predator responses to exclosures and other stimuli at shorebird nests. We used location data from GPS-collared red foxes (Vulpes vulpes) to examine short-term spatial responses of foxes to exclosure setup and hatching at piping plover (Charadrius melodus) nests on Fire Island, New York. We compared mean distances between fox locations and piping plover nests, and the proportions of fox locations within a 100-m buffer of nests, before and after exclosure setup and before, during, and after hatching. Mean distances from fox locations to nests were similar before versus after exclosure setup (x = 641 m before, 675 m after; permutation test for matched pairs, [PTMP], T = 0.28, P = 0.56, n = 9 foxes), before versus during hatching (x = 417 m before, 340 m during; PTMP, T = -0.93, P = 0.18, n = 5 foxes) and during versus after hatching (x = 340 m during, 330 m after; PTMP, T = 1.00, P = 0.84, n = 5 foxes). The proportions of fox locations within 100-m buffers surrounding nests were similar before versus after exclosure setup (x = 0.01 before, 0.03 after; PTMP, T = 0.26, P = 0.53, n = 9 foxes), before versus during hatching (x = 0.04 before, 0.15 during; PTMP, T = -1.44, P = 0.09, n = 5 foxes), and during versus after hatching (x = 0.15 during, 0.14 after; PTMP, T = 0.84, P = 0.80, n = 5 foxes). In 10 of 19 of our individual-level comparisons, there were no significant differences in the distances from fox locations to nests between paired event periods. In the other 9 individual-level comparisons, we found evidence of shifts in fox space use between paired event periods, but no clear directional trend across individuals. We conclude that the foxes in our study did not appear to consistently key in on exclosure setup or hatching at piping plover nests at the spatial scales considered in our comparisons. We recommend that managers continually re-evaluate the effects of exclosures at their management sites, as changes in nest predation, abandonment rates, and adult plover survival may all influence the relative benefit of exclosures for population growth. Our study illustrates the potential for using spatial data to investigate predator responses to various management actions taken to protect nesting shorebirds and other prey species of conservation interest.