Geology topics

Peter F. Rebholz

Publications and source records attributed to Peter F. Rebholz.

5 recordsLinked to original sources

USGS2026

Evidence of ringtail expansion into Idaho, USA

Ringtails ( Bassariscus astutus ) are widely distributed in the western United States and across much of Mexico, yet due to their relatively low densities and cryptic nature, little is known about their basic ecology even where they are common. Recent public sightings suggest ringtails may have expanded their distribution north into southern Idaho, USA. Currently, ringtails remain unclassified in Idaho thus limiting resources and time available for population monitoring. We attempted to detect these small carnivores in southern Idaho during winter 2023. We deployed 49 camera traps with a combination of lures (i.e., trapping lure, fruit, and orange drink mix) in canyon habitats in southern Idaho near recent ringtail sightings. We detected ringtails nine times on six different camera traps. Although incidental ringtail observations increased in southern Idaho since the early 2000s, our detections were the first to result from a targeted survey effort. Given more than 20 years of incidental sightings and multiple detections during our survey, it appears that ringtails have expanded their range northward into southern Idaho and could be considered a resident species in the state. Further efforts to document reproduction, annual persistence, and an assessment of threats could be next steps if the state wildlife management agency deems it a priority and an appropriate use of resources.

Idaho↗

USGS2025

Linking age and social status of cooperative breeders to vulnerability throughout the harvest season

Individual behaviors are influenced by environmental, genetic, and demographic factors. Some animals choose to live in groups and cooperatively breed, and their behaviors can change depending on dynamic factors such as group size and composition that affect group persistence. In Idaho, USA, gray wolves ( Canis lupus ) are harvested annually, providing an opportunity to investigate the effects of harvest and seasonal behaviors on a population of cooperative breeders. These annual hunting and trapping seasons overlap with the dispersal and breeding periods for wolves and we do not know how harvest affects the vulnerability of different sex and age classes during these important biological periods. We applied 9 years (2009–2018) of genetic, age, and harvest data from harvested wolves to investigate how behaviors (dispersal and breeding) and biological drivers might influence the vulnerability of wolves to harvest. We created pedigrees from genotypes of non-invasively collected scats to estimate the expected proportion of the wolf population composed of 3 different age classes (pup, yearling, and sexually mature or ≥2 years old) and compared them to the observed number of each age class harvested during biologically significant periods (i.e., dispersal and breeding). We found that pups were more vulnerable to harvest in December when wolf harvest transitioned largely to trapping (accounts for 66% of harvest), and found evidence that adults were more vulnerable to harvest during their breeding season in January and February. In contrast, we found no difference in the expected versus observed number of wolves ≥2 years old in the harvest during peak dispersal season (December), or in the expected versus observed number of yearlings in the harvest during September and October when pups are mobile and groups of wolves abandon the use of pup-rearing sites. Some age classes were disproportionally harvested during certain periods for specific years, but this was not consistent across all years, suggesting there is more to learn about the vulnerability of different age classes to harvest. We found harvest can disproportionally affect some demographic classes of individuals depending on year, biological period, and harvest type. With wolves continuing to recolonize historical ranges, our approach can benefit managers and future studies with the goal of identifying how interannual harvest affects groups of wolves.

Idaho↗

USGS2024

Gray wolf breeders are more vulnerable to harvest during the breeding season

In cooperatively breeding carnivores, breeders are vital to perpetuating the group; the death or removal of an individual breeder can greatly affect group composition, genetic content, and short-term population growth. Understanding the number of breeders harvested and timing of harvest can increase our knowledge of how mortality affects groups of cooperative breeders. Gray wolves ( Canis lupus ) in Idaho, USA, are exposed to annual harvest and are an ideal species for studying the effects of harvest on breeder turnover. We combined genotypes from tissue samples of harvested wolves with parentage analyses and cementum annuli ages and estimated when and how many breeding wolves were harvested. We genotyped and aged 229 adults and 203 pups using tissue and tooth samples from wolves harvested between 2014 and 2016. We identified a minimum count of 33 breeders in the harvest and found that they were disproportionately harvested more during the breeding season. We estimated that a minimum of ~14.5% of adult wolves harvested annually, or approximately 1 in 7, were breeders. We posit their behavior during breeding season may increase their vulnerability to harvest. By linking animal life history with vulnerability to human-caused mortality we show that managers could structure harvest seasons so there is less overlap with wolves’ breeding season if there is concern about the demographic consequences of harvesting breeders.

Idaho↗

USGS2024

The effects of human-caused mortality on mammalian cooperative breeders: A synthesis

Human-caused mortality can be pervasive and even highly selective for individuals in groups of cooperative breeders. Many studies of cooperative breeders, however, do not address human-caused mortality. Similarly, studies focused on the effects of human-caused mortality on wildlife populations often do not consider the ecology of cooperative breeders. We searched the literature and identified 58 studies where human-caused mortality affected a group characteristic, vital rate, or population state of a cooperative breeder. Of studies reporting population growth or decline, 80% reported a link between human-caused mortality and population declines in cooperative breeders. Such studies often did not identify the mechanism behind population declines, but 28% identified concurrent declines in adult survival and another 21% reported concurrent declines in recruitment or reproduction. There was little overlap between the cooperative breeding and human-caused mortality literatures, limiting our ability to accrue knowledge. Future work would be beneficial if it ( i ) identified the vital rate(s) causing population declines, ( ii ) leveraged management actions such as lethal removal to ask questions about the ecology of group-living in cooperative breeders, and ( iii ) used insights from cooperative breeding theory to inform management actions and conservation of group-living species.

Biological Reviews↗

USGS2024

Treat yourself: Pilot testing a new method to treat mange in wild carnivores

Mange is a skin disease caused by mites that parasitize an animal's skin, often yielding inflamed immune responses and hair loss. At a population level, mange may reduce survival and cause population declines. Many forms of mange can be treated quite effectively when an animal is in hand; however, this is not often feasible for many free-ranging wildlife populations. Some animals, particularly territorial carnivores, will rub or roll to scent mark and transmit information about their presence to other individuals. We posited that rub stations comprised, in part, of anthelmintic medication and foreign scents that induce rubbing could be used to remotely treat mange in the wild. We deployed 39 rub stations containing lure and dye in Santa Monica Mountains National Recreation Area, Southern California, USA, October–November 2022. Carnivores rubbed or rolled at .97% of rub stations, with coyotes ( Canis latrans ), gray foxes ( Urocyon cinereoargenteus ), and bobcats ( Lynx rufus ) being the most abundant species. Time to first rub or roll was generally <1 wk. Several sympatric species (e.g., mule deer, Odocoileus hemionus ) were detected at rub stations but did not rub. Our pilot test provides strong evidence that treating mange in wild carnivores may be possible using the remote medicinal rub stations we describe. Future efforts to add medicine to rub stations and monitor for a change in mange prevalence are a logical next step.

Journal of Wildlife Diseases↗