Human-wildlife conflicts are an important factor for consideration in wildlife management at urban-wildland interfaces. Effective and adaptive management of human-wildlife conflicts is needed to promote tolerance and coexistence of humans and wildlife. Anecdotal reports suggest a recent spike in human-elk conflicts in California, yet there has not been a systematic analysis of human-elk conflicts in the state. To better understand human-elk conflicts in California, we conducted thematic analysis of human-elk conflicts reported in the California Department of Fish and Wildlife’s Wildlife Incident Reporting (WIR) system. We also conducted a hotspot analysis using locations of human-elk conflicts reported in the WIR system and evaluated reports for principles of adaptive management. The WIR system contained n = 89 reports for elk and n = 78 of these described conflicts with elk. Overall, property damage (including crop damage) was the most common type of human-elk conflict reported, occurring in 69% of reports (n = 54/78), followed by non-competitive conflict with domestic animals (13%), competition with domestic livestock (12%), and habituation to humans (24%). We identified three hotspots of human-elk conflict in California in Del Norte, Kern, and San Luis Obispo counties. All incidents of human-elk conflict reported in the WIR system included at least one principle of adaptive management. We recommend modifications to the WIR system and interactions with property owners and stakeholders to enhance and facilitate adaptive management of human-elk conflicts in California.
Concrete-lined water conveyance canals can be a significant source of mortality for ungulates and other wildlife, which can drown or become entrapped. Various types of wildlife escape structures have been deployed in canals with limited success. From 2011 to 2018, we used camera traps to monitor mule deer (Odocoileus hemionus) use of three different temporary wildlife escape structure designs with the goal of developing an effective escape structure for fawns. We monitored three to five locations at a hydroelectric water conveyance canal, operated by Pacific Gas and Electric Company in the foothills of Central California on the Sierra National Forest, in which trapped fawns had been detected previously during the maintenance period when the canal was dry. Mule deer activity and ramp use varied by year. During the monitoring period, deer were detected in the canal in all years except 2016 and 2017. Fawns and adults used the temporary escape structures to exit the canal in four of these years and 50% of mule deer detections showed ramp use overall. No deer were detected using the escape structures until jute netting and debris were added to the surface of the escape ramps in the third monitoring year. Prior to this modification, fawns were detected trapped in the canal investigating the ramps, but not using them to exit the canal. Deer may be more likely to utilize ramps covered with materials that mimic native ground cover. Seven other wildlife species were detected entering and exiting using the ramps with a general increase in use over years. Our temporary escape ramp design for small canals, when dry, appears to be novel and may be applicable in other areas. When compared to fencing or covering the canal, it is a relatively low-cost solution to reduce animal entrapment.
Black bear (Ursus americanus) populations in California have increased in abundance and distribution despite rising trends in the urban encroachment of wildlands. As human-black bear conflicts increase, opportunities to study the relocation of black bears in an adaptive management setting are important for improving the management of this high-profile species. Habituated black bears, some tamed and made tractable through human-controlled food conditioning, were relocated to a remote region of the Klamath Mountains to analyze home range use, survival, return rates, and mortality. Relocated black bears with known outcomes demonstrated an 80% return rate, with 55% not surviving beyond five months. Female bears established home ranges significantly larger than males, and may suggest an enhanced maternal instinct in search of similar nutritional conditions prior to relocation. This study showed that the relocation of food-conditioned black bears resulted in high return rates, poor survival, and risk to public safety.
The California Department of Fish and Wildlife (CDFW) uses fiberglass mate-rial for forensic analysis of oil sheens, while the United States Coast Guard (USCG) method uses a tetrafluoroetheylene-fluorocarbon (TFE-fluorocarbon) polymer net. We performed a field trial of these two materials by sampling natural oil seeps, two in Santa Monica Bay, and three sheen areas in the Santa Barbara Channel. Though the fiberglass material did collect less mass on some trials, the forensic chemistry results demonstrated that both materials were satisfactory for purposes of chemical forensic analysis as each pair of the sampling materials yielded results that were consistent with a common oil seep source.
Livestock operations in California face livestock losses due to a range of carnivore species. Simultaneously, there is an increased call to reduce the use of lethal predator control methods and replace them with nonlethal methods. Livestock guardian dogs (Canis lupus familiaris) are one such nonlethal livestock protection tool (LPT), yet research is still lacking on the factors and situations that impact their effectiveness. Using three case studies, we demonstrate the value of objective analyses that explicitly address the inherent differences in ranch management, environment, and surrounding land uses in examining livestock guardian dogs as an LPT. We used semi-structured questionnaire surveys of livestock operators to collect information on effectiveness, behavior, and producer satisfaction of LGDs protecting poultry (Gallus gallus domesticus), calves (Bovus taurus), and sheep (Ovis aries) on private and public land and in conjunction with a variety of other livestock protection tools. We aimed to address all aspects related to the use of LGDs as a means of informing livestock operators’ decisions on whether LGDs are an appropriate tool for a particular operation. The case studies demonstrated the complexities involved in applying LGDs as a LPT within the context of a livestock operation. In two of the three case studies, LGDs did not entirely eliminate livestock losses yet operator satisfaction remained high.
To inform management and conservation of the species, we investigated the distribution of anadromy and residency of steelhead/rainbow trout (Oncorhynchus mykiss) in the Eel River of northwestern California. We determined maternal anadromy versus residency for 106 juvenile O. mykiss using otolith microchemistry. To attempt to relate patterns of anadromy with environmental factors known to influence its distribution in O. mykiss in other places, fish were collected from 52 sites throughout the drainage covering a range of stream size (0.1–7.7 m3/s estimated mean annual run-off) and distance from the ocean (23–219 km). Sixty-one of 91 fish sampled below prospective barriers had anadromous mothers, while 1 of 15 fish sampled above barriers had an anadromous mother. We did not detect any influence of stream size or distance from the ocean on the occurrence of anadromy. Fish with resident mothers were found at 21 of 46 sites below barriers. The current broad distribution of fish with resident mothers indicates the importance of maintaining freshwater conditions suitable for resident adults and juveniles age-1 and older, such as preserving dry-season streamflows.
Recent museum, archaeological, and observer record evidence suggests that North American beaver (Castor canadensis) were historically native to the watersheds of California's coast, including San Francisco Bay. A wide variety of animals are abundantly represented in Native American petroglyphs and pictographs with their representations fulfilling intentions ranging from the mundane to ceremonial and mythological purposes. However, beaver symbols are poorly represented in California rock art and absent from the San Francisco Bay Area. A novel record, in the form of Western Message Petroglyphs, suggests that a beaver lodge was present in the late nineteenth century in the Alameda Creek watershed, potentially the last evidence of beaver prior to their extirpation in the region by the fur trade.
Survival during the nonbreeding season, when mortality from food shortages and raptor predation is highest, influences shorebird population growth. These selection pressures, as well as anthropogenic influences, can shape wintering shorebird habitat use patterns. The western snowy plover (Charadrius alexandrinus nivosus) is a small shorebird that uses sand-spits, dune-backed beaches, open areas around estuaries for foraging and roosting. The Pacific Coast population of western snowy plovers is listed as a federally threatened species and a California Species of Special Concern. Previous studies suggest humans, dogs and corvids are sources of disturbance to plovers on public beaches. During 2014 to 2019, these disturbance factors were examined at Robert W. Crown Memorial State Beach in Alameda, California. In decreasing order of impact, the beach using public, corvids, and dogs were found to be the major stressors to over wintering plovers. Both the public and corvids respectively, resulted in disturbance and avoidance behaviors by plovers nearly 40% of the time. In 2015, the District created the Plover Protection Zone (PPZ) by installing symbolic fencing, signage, and establishing a volunteer team to monitor plovers and educate the public. In 2016, the potential prey abundance within the plover protection zone and areas directly north and south were examined using core samples and sticky traps. Statistical analysis showed a significant difference in the amount of macro-invertebrate prey available in the area used by the plovers as compared to other locations. Habitat choice and prey availability are vital to wintering shorebird. During this study, the wintering population of western snowy plovers increased from six to over 54 individuals.
Photovoltaic solar power generating facilities are proliferating rapidly in California and elsewhere. While this trend is welcomed for many reasons (e.g., reducing greenhouse gas emissions), these facilities also can have profound environmental impacts, particularly to local species populations. These impacts become more significant when species of conservation concern are affected. In the San Joaquin Desert region in central California, a number of conservation measures have been routinely implemented on solar facilities, and these measures have facilitated continued use of the facilities by a number of species of conservation concern. Some of the more significant measures include permeable security fences, vegetation management, movement corridors, avoiding critical features such as dens and burrows, and vehicle speed limits. Detailed studies have been conducted on San Joaquin kit foxes (Vulpes macrotis mutica) using solar facilities in the San Joaquin Desert. Demographic and ecological attributes of foxes are similar between foxes using the facilities and foxes on nearby reference sites, and values for foxes on solar sites are within the ranges of values for foxes reported from sites within core population areas. Facilitated by the conservation measures, kit foxes are using at least six facilities in the San Joaquin Desert as are a variety of other species of conservation concern. This successful model also potentially could be adapted to other ecosystems and applied to facilities in regions outside of the San Joaquin Desert, such as the Mojave Desert. Determining whether species in other regions can use photovoltaic solar facilities and identifying the most efficacious conservation measures will require time and testing, and these efforts would benefit from collaborative efforts among landowners, solar developers, natural resources agencies, researchers, and others. The San Joaquin Desert facilities and a recent demonstration facility in the Mojave Desert provide strong evidence that solar facilities can be constructed and operated in a manner that also accommodates continued use of the facilities by some species of conservation concern.
2015; Murray et al. 2019). For a time, the boon of ecotourism seemed an irreproachable alternative to the extractive exploitation of wildlife, and many communities derived benefits by preserving living, thriving natural areas and encouraging tourism in a non-consumptive manner (Duffus and Dearden 1990;Gössling 1999;Stronza et al. 2019).However, as more people have sought experiences in nature and encounters with wildlife, the risks of overcrowding sensitive habitats and disturbing the vital behavior patterns of the species living in those habitats have mushroomed.Without intervention, upsurges in outdoor recreation (e.g.,
Recreational fishing for Rainbow Trout (Oncorhynchus mykiss) is important economically in California. We determined the upstream and downstream distribution of Rainbow Trout in a southern California stream, and classified all available habitat within that area as riffle, pool, cascade-pool-complex, and flatwater. Approximately 10% (based on length) of each habitat type was sampled using depletion electrofishing. We estimated Rainbow Trout abundance, both <100 mm and ≥100 mm, by extrapolating average number of fish per m² in each habitat type sampled to the total m² of each habitat type. A total of 854 fish were captured, with the greatest proportion coming from the cascade-pool-complex habitat type, followed by pool, flatwater, and riffle. The population estimate for Rainbow Trout <100 mm was 1,763 fish (95% CI ±442), and for Rainbow Trout ≥100 mm was 5,383 fish (95% CI ±1,688).
Ecological attributes of a species can vary as resource requirements and social interactions change in response to the annual reproductive cycle. We examined variation in home range size, home range overlap, activity (2005–2006), and food item selection (2006–2007) of island foxes (Urocyon littoralis) on San Nicolas Island relative to reproduction-related events. Home ranges, particularly for males, were larger during the mating period compared with the post-mating, pup-rearing, and non-reproduction periods. Home range overlap with non-mate neighbors also increased during the mating period. The greater home range size and overlap during the mating season is consistent with foxes, particularly males, traveling into the ranges of neighboring pairs in an attempt to secure extra-pair copulations. Daily activity patterns did not vary among the reproductive periods. Use of vertebrate prey items increased during the period when adults would have been provisioning weaning young. These items (e.g., mice, birds, lizards) are protein-rich and easier to transport compared with smaller items (e.g., fruits, snails, insects) that also are commonly consumed by island foxes. Variation in ecological attributes among island foxes across the different seasons defined by reproductive events likely represents efforts to maximize mating opportunities, particularly among adult males, and to secure optimal resources for provisioning growing young. These patterns are consistent with those observed among other small canid species.
The Tipton kangaroo rat (Dipodomys nitratoides nitratoides; TKR) is listed as endangered both Federally and by the state of California due to profound habitat loss throughout its range in the southern San Joaquin Valley of California. Habitat loss is still occurring and critical needs for TKR include identifying occupied sites, quantifying optimal habitat conditions, and conserving habitat. Our objectives were to (1) conduct surveys to identify sites where TKR were extant, (2) assess habitat attributes on all survey sites, (3) generate a GIS-based model of TKR habitat suitability, (4) use the model to determine the quantity and quality of remaining TKR habitat, and (5) use these results to develop conservation recommendations. We surveyed for TKR on 44 sites by live-trapping and detected TKR on 15 sites. Sites with TKR tended to have larger alkali scalds and no obvious sign of past tilling compared to sites without TKR. Also, sites with TKR usually had relatively sparse ground cover and seepweed (Suaeda nigra) was present. The non-protected Heermann’s kangaroo rat (Dipodomys heermanni), a larger competitor, was either absent or present in relatively low numbers at sites with TKR, and when present its abundance was inversely related to that of TKR. Based on our habitat suitability modeling, an estimated 30,000 ha of moderately high or high quality TKR habitat and 60,000 ha of lower or medium quality habitat remain. However, habitat is still being lost and conversion of at least one survey site with TKR occurred during this project. Recommendations for TKR conservation are to (1) conduct additional TKR surveys on unsurveyed but suitable sites, (2) conserve suitable habitat on unprotected lands, (3) manage vegetation on occupied sites if necessary, (4) restore disturbed lands to increase suitability for TKR, and (5) research methods and conduct translocations of TKR to unoccupied sites with suitable habitat.
