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- Flea Abundance, Species Composition, and Prevalence of Rickettsioses from
Urban Wildlife in Orange County, California, 2015-2019
Abstract: Fleas infesting urban wildlife have been epidemiologically linked to the transmission of flea-borne rickettsial pathogens in urban and suburban areas of Orange County, California. To understand the prevalence of flea-borne rickettsioses caused by either Rickettsia felis or R. typhi, a survey of fleas from wildlife was conducted to determine the flea species composition of host animals and prevalence of rickettsial pathogens in fleas on host animals. This study reports flea abundance, species composition, and infestation intensity on unowned domestic cats and wildlife (i.e., coyotes, opossums, rabbits, skunks, squirrels, raccoons, and commensal rodents) collected in urban neighborhoods of Orange County. The survey revealed presence of the northern rat flea on eastern fox squirrels, and widespread distribution of the human flea on skunks and coyotes in Orange County. The flea index and prevalence of flea-bone rickettsioses in fleas has been used by the Orange County Mosquito and...
PubDate: Thu, 4 Mar 2021 00:00:00 +0000
- Vector Control in Oakland’s Homeless Encampments
Abstract: Homeless encampments are a persistent feature in the city of Oakland, California. Unsanitary conditions in these camps can contribute to large populations of Norway rats and associated vector-borne disease. Alameda County Vector Control Services District has developed a surveillance program for safe and efficient data collection in these encampments. This program includes outreach to residents, effective live-trap ping, ectoparasite collection, vector species suppression, and coordinating with other agencies. The District’s operations around Oakland’s pilot “Tuff Shed” homeless shelter strategy are presented as a case study for Norway rat and Oriental rat flea risk assessment and control.
PubDate: Wed, 13 Jan 2021 00:00:00 +000
- Preliminary Field Efficacy of Anthraquinone Repellent to Reduce Drip
Irrigation Line Damage by Cottontail Rabbits
Abstract: Unmanaged cottontail rabbit populations can cause significant damage to drip irrigation tubing. Common integrated pest management strategies to reduce damage include trapping, exclusion, and repellent use. Trapping and exclusion, while effective at managing cottontail rabbits, are impractical when applied to large scale habitat restoration projects. To evaluate repellent use under these conditions, we conducted a preliminary conditioned avoidance field trial using anthraquinone applied to drip irrigation tubing installed in a riparian habitat undergoing restoration in Silverado, CA. The postingestive repellent, anthraquinone, was selected due to prior laboratory research indicating its effectiveness in inducing conditioned avoidance feeding behaviors in cottontail rabbits. Following a complete repair of the irrigation system, alternating sections of the irrigation tubing were treated. After the first treatment, there was an estimated 50% reduction in damaged tubing between the...
PubDate: Wed, 13 Jan 2021 00:00:00 +000
- Integrated Pest Management Strategies for Round-tailed Ground Squirrels
Abstract: Round-tailed ground squirrels are common residents of natural areas throughout most of the desert southwest region of North America. They live in colonies of several adults, subadults, and young, and are diurnal during the active season that ranges from March to September. They are well adapted to desert life and live in burrows they excavate in the ground, but will also modify and occupy burrows created by other animals. Round-tailed ground squirrels are frequently seen in many human community environments. Their burrowing is usually not a significant cause of concern, nor do they cause severe damage to humans or their property. However, they very often cause concerns due to human-wildlife interactions that may include the squirrels themselves, but also their predators such as rattlesnakes, coyote, feral dogs, and other large mammals. Another cause for concern is that round-tailed ground squirrels can be hosts for fleas and other parasites and could vector plague or other diseases...
PubDate: Wed, 13 Jan 2021 00:00:00 +000
- Pest Control by Generalist Predators Depends on Prey Density and Predator
Effectiveness
Abstract: Integrated Pest Management (IPM) strategies increasingly incorporate natural predators of pest species to reduce the abundance and persistence of pest species in agricultural settings. Specialist predators and parasitoids have been demonstrated to be successful tools to reduce the damage from invertebrate pest species, but less research has focused on the effectiveness of generalist predators to reduce the abundance of vertebrate pest species. To investigate this, we employed a case study of a globally used IPM tactic: the use of barn owls (Tyto alba) for rodent biocontrol. When used as a biocontrol agent, barn owls are typically recruited to the area through the installation of nest boxes in agricultural fields. Anecdotal evidence suggests that barn owls forage within the agricultural fields and reduce rodent pest populations, but no replicated studies that monitor both rodent and owl populations exist to date. We developed models of this system, parameterized using published...
PubDate: Wed, 13 Jan 2021 00:00:00 +000
- Do the Remains Remain' The Fate of Bird Carcasses in a Hawaiian
Rainforest that is Fenced for Ungulates and Managed for Rodents using A24
Self-resetting Traps
Abstract: The introduction of rodents to islands poses a threat to native fauna, which often have no adaptation to defend their offspring or themselves from predation. To combat predation of nests and brooding females, the Kauai Forest Bird Recovery Project (KFBRP) has deployed 425 Goodnature A24 self-resetting rat traps at two field sites where high densities of native forest birds remain. One site is fenced to exclude invasive ungulates. KFBRP conducts routine trap checks every four months to assess bait and trap function and count carcasses. Typically, we find 0-3 rat or mouse carcasses at a trap, but in November 2018, we found a dead bird under a trap at the fenced site. We assume that traps kill more animals than indicated by carcass counts, because 75% of traps have counters that record when traps fire, and counter tallies exceed carcass counts. Thus, we hypothesize that some carcasses are scavenged or decompose between trap checks, and as a result we are a) underestimating target...
PubDate: Wed, 13 Jan 2021 00:00:00 +000
- Consumption of Rat Carcasses as a Pathway of Rodenticide Exposure of
Wildlife in Southern California
Abstract: The high toxicity and effectiveness of anticoagulant rodenticides have led to their widespread use for controlling rodent pests; however, significant concerns remain about the potential exposure of non-target wildlife species at the urban-wildland interface. Such species can be exposed by consuming toxic baits directly, or indirectly, by scavenging rodenticide-killed prey (secondary exposure). To investigate opportunities for secondary exposure, we used Reconyx digital game cameras to quantify the fates of 20 rat carcasses placed in residential backyards in Orange County, California. We anchored rat carcasses to the ground and then followed their fates for seven days or until carcasses were removed. We also recorded yard characteristics (e.g., vegetation density, permeability of exterior barriers, presence of pets, water, and anthropogenic foods) to help explain variation in carcass removal rates between yards. Rats were discovered fairly quickly, with 35% of carcasses visited...
PubDate: Wed, 13 Jan 2021 00:00:00 +000
- Survey of Ectoparasites Collected from Norway Rats (Rattus norvegicus) in
Homeless Camps in the City of Oakland, California
Abstract: The City of Oakland is the largest city within Alameda County, the 8th largest city in California, and the 45th largest in the United States. Due to various socioeconomic factors, the number of homeless encampments within Oakland has been increasing over the past few years. A recently completed survey showed that there has been a 47.45% increase in the number of homeless living within the city limits. Approximately 4,071 people are now living in various encampments around the city, primarily concentrated underneath freeway/infrastructure overpasses and on adjoining lands. Surveillance by our staff found that several of these encampments also had active Norway rat populations as indicated by active burrows within and adjacent to the camps, as well as resident reports. Beginning in the fall of 2017, District biologists began live-trapping at a few of the larger encampments to try and ascertain the composition and load of ectoparasites on corresponding Norway rat populations. We...
PubDate: Wed, 13 Jan 2021 00:00:00 +000
- Homeless Encampments Characteristics Critical in Reducing Vector-Borne
Disease Potential
Abstract: As of January 2019, a survey of homeless people in Alameda County, CA, documented 8,022 homeless individuals countywide, including 6,312 unsheltered people. Dozens of homeless encampments exist throughout the County, and most lack sanitation facilities (e.g., rodent-proof garbage storage and weekly waste removal; sanitary toilets; and running water for hand washing, showering, or laundry). This situation represents a breakdown of the sanitation interventions that can lead to the outbreak of vector-borne disease (e.g., 2020 outbreaks of flea-borne typhus in southern California). Some characteristics of surveyed encampments make them more or less suitable for Norway rat population establishment and the exhibition of problems associated with rodent ectoparasites. Many urban encampments are in parts of Oakland that have old infrastructure including sewers that support an endemic population of Norway rats and where there may be undetected sewer breaks that allow these rats into these...
PubDate: Wed, 13 Jan 2021 00:00:00 +000
- Evaluating Habitat Manipulation as a Strategy for Rodent Control in
Agricultural Ecosystems of Pothwar Region, Pakistan
Abstract: Habitat manipulation is an important technique that can be used for controlling rodent damage in agricultural ecosystems. It involves intentional manipulation of vegetation cover in habitats adjacent to active burrows of rodents to reduce shelter and food availability and to increase predation pressure. The current study was conducted in the Pothwar Plateau region of Pakistan during respective non-crop periods of wheat-groundnut (post-harvested and un-plowed/non-crop fallow lands). The purpose was to assess the impact of reduction in vegetation height of adjacent habitats (field borders) on rodent richness and abundance. The study area was divided into two sites: treated and non-treated. At the treated sites, habitat manipulation was carried out by removing crop cache and non-crop vegetation over 10 cm in height to a distance of approximately 20 m from the fields. The trapping sessions carried out at both treated and non-treated sites adjacent to wheat-groundnut fields were...
PubDate: Wed, 13 Jan 2021 00:00:00 +000
- Do Coyotes Eat Mesocarnivores in Southern California' A Molecular
Genetic Analysis
Abstract: Urban coyotes are commonly exposed to rodenticides used to control non-native commensal rodents, but these rodents are rare in published accounts of their diets. An alternative source of rodenticide exposure is through the consumption of mesocarnivores that have themselves eaten either toxic bait directly or poisoned rodents or invertebrates. Carcasses of 311 nuisance and road-killed coyotes from suburban and urban areas of southern California were collected from 2016-2018. Stomachs were dissected and prey items were identified visually. Stomach contents containing tissue from suspected mammalian prey (N = 178) were homogenized and DNA was extracted. Genus-specific primers (123-366 bp) were designed for Virginia opossums, raccoons, and striped skunks, regionally common species that are known to be consumed by coyotes. PCR was performed for each primer pair, and presence of PCR products of particular amplicon lengths were determined by gel electrophoresis. Coyote stomachs containing...
PubDate: Wed, 13 Jan 2021 00:00:00 +000
- Current Trends and Management of Wild Horses on the Devil’s Garden
Plateau
Abstract: In Modoc County, located in northeastern California, there is a high elevation sage-steppe rangeland ecosystem heavily populated by wild horses and managed primarily by the United States Forest Service (USFS) called the Devil's Garden Plateau. Wild horses have significantly exceeded (roughly 2,000 horses) appropriate management levels (206-402 horses) in recent years and expanded their range outside of the designated territory (258,000 acres) and onto private and tribal lands (nearly 500,000 acres). Increased pressure from wild horses on the multiple use mandate of Forest Service lands have put strains on livestock, wildlife, and the local rural economy. The Modoc National Forest has decreased grazing by roughly 5,000 AUMs (animal unit months) on the Devil’s Garden Plateau due to excessive wild horse use. Each lost AUM results in a decrease of $57.43 - $144.70 of income to Modoc County. Three helicopter gathers in recent years have removed over 1,500 horses from the Devil’s Garden...
PubDate: Wed, 13 Jan 2021 00:00:00 +000
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