Wildlife Predation Research Articles

Predator-Prey Relationships: The Manager’s Perspective

Predation effects have been studied since the early days of wildlife management, with the goal of wildlife managers to balance wildlife populations with available habitat and management objectives. Still, research and public debate focuses on the degree to which vegetative carrying capacity (K) affects prey and the degree to which predation management could benefit prey species. K, to this point, has not generally considered the secondary effects that predators have on prey habitat availability. When setting wildlife management objectives, the relationship of predation impacts (i.e., factors that may cause mortality in a given species) to prey and available habitat and habitat availability must be examined carefully and understood. This paper discusses classic predator-prey relationships and the potential effects of secondary predation on prey. Managers must consider these effects and relationships to determine if, when, and how to implement an effective wildlife enhancement or predation management strategy.

The Domestic Cat as a Predator of Israeli Wildlife

Predation of wildlife by domestic cats was studied in Israel. Analysis of stomach contents and data provided by observers revealed that many domestic cats enriched the diet provided by their owners with many species of wild animals, including 12 mammals, 26 birds, 18 reptiles, and one amphibian, and scavenged from garbage. The proportion of manufactured cat food and garbage dump food in the diet of urban cats decreased from 70% of stomach volume among those living in rural settlements to 44% among cats living in open areas, with the rest of the stomach contents consisting of wild animals. Of the wild animals hunted by cats, the most common category was mammals (75% of the stomach volume), followed by amphibians (10%), birds (9%), and reptiles (6%). Most cats do not wander more than 200 m away from either a food source or cover. Female cats living in (southern) desert settlements do not leave the inhabited area and have very small home ranges, while those living in the Mediterranean region (central and nor...

Integrated Vegetation Management On An Electric Transmission Right-Of-Way In Southeastern Pennsylvania, U.S.

Integrated Vegetation Management (IVM) via the wire­border zone method has been used for the maintenance of vegetation along an electric utility transmission right-of-way (ROW) at the Green Lane Research and Demonstration Area, Montgomery County, Pennsylvania, U.S., since 1987. The wire­border zone method creates a forb­grass­short shrub cover type in wire zones and a tall shrub cover type in border zones. The Green Lane Research and Demonstration Area has been studied annually since 1987, which makes this 18-year-old project one of the longest continuous studies documenting the effects of mechanical and herbicidal maintenance on flora and fauna along an electric transmission ROW. In this paper, our objective is to present target (undesirable) tree density and cover-type development in response to IVM prior to the most recent treatment (June 1999) and 4 to 5 years after treatment. Excellent control of target trees was noted in 1999 in wire zones of mowing plus herbicide units; in contrast, tree control was poor in wire zones of mechanical units (mowing and handcut). Maximum tree height averaged 4.3 m (14 ft) and 4.9 m (16 ft) in wire and border zones, respectively. Immediately prior to the 1999 treatment of the Green Lane ROW, cover types in wire zones of herbicidal units (mowing plus herbicide, stem­foliage spray, and foliage spray) were classified as shrub­forb­grass­tree, whereas types in border zones of these units were tree­shrub­forb. Both wire and border zones of mechanical units were considered tree­shrub­forb cover type. The overall density of target trees increased 7.3% and 26.4% in wire zones and border zones, respectively, in 2004 compared to 2003. From 1999­2004, the most common target tree species on the Green Lane ROW was white ash (Fraxinus americana). In both 2003 and 2004, shrubs and forbs were the most important cover types in wire zones of all treatment units; grass cover type, however, was important in wire zones of five of the ten units. IVM of a ROW is a "tree resistant" but not a "tree proof " means of reducing tree invasion. Competition with existing plants and wildlife predation on tree seeds on a ROW managed via the wire­border zone method keeps tree invasion to a minimum. Thus, over the years since 1987, IVM and the wire­border zone method of ROW maintenance have increased the time between treatment cycles, thereby reducing labor and chemical costs for ROW maintenance.

The efficacy of collar-mounted devices in reducing the rate of predation of wildlife by domestic cats

Volunteer cat owners from across the UK were recruited to take part in two trials designed to test the efficacy of collar-mounted warning devices in reducing cat predation rates of native wildlife. Cats equipped with a bell returned 34% fewer mammals and 41% fewer birds than those with a plain collar. Those equipped with an electronic sonic device returned 38% fewer mammals and 51% fewer birds compared with cats wearing a plain collar. There was no significant difference in prey return rates by cats wearing collars equipped with one bell, two bells or the sonic device. Warning devices mounted on quick-release collars are recommended as an effective way of reducing wildlife kill rates by domestic cats. Future research and development aimed at further improving the efficacy of sonic devices is recommended.

Straw Mulch Prevents Loss of Fall-Sown Seeds to Cold Temperatures and Wildlife Predation

Straw Mulch Prevents Loss of Fall-Sown Seeds to Cold Temperatures and Wildlife Predation

Integrated Vegetation Management On An Electric Transmission Right-Of-Way In Pennsylvania, U.S.

Integrated vegetation management (IVM) has been used for the maintenance of vegetation along an electric utility transmission right-of-way (ROW) at the State Game Lands (SGL 33) Research and Demonstration Area, Centre County, Pennsylvania, U.S., since 1987. In addition, the wire­border zone method was implemented on the ROW in 1987. The wire­border zone method results in forb­grass­shrub cover types in wire zones and shrub cover types in border zones. The SGL 33 Research and Demonstration Area has been studied since 1953, which makes this 51-year-old project the longest continuous study documenting the effects of mechanical and herbicidal maintenance on flora and fauna along an electric transmission ROW. In this paper, our objective is to present target (undesirable) tree density and cover-type development in response to IVM prior to the most recent treatment (2000) and 2 to 3 years after treatment. Results were compared to those obtained from the late 1980s and 1990s. For all units combined (except handcut) in 1999, average target tree densities prior to treatment were 288 trees/ha (117 trees/ac) in wire zones and 759 trees/ha (307 trees/ac) in border zones. Excellent control of target tree density [62 to 124 trees/ha (25 to 50 trees/ac)] was noted in wire zones of mowing plus herbicide, stem­foliage spray, and foliage spray units; moderate control [371 to 680 trees/ha (150 to 275 trees/ac)] was observed in low-volume basal spray, high-volume basal spray units, and mowing units; and poor control (4,818 trees/ha [1,951 trees/ac]) was found in the handcut unit. In 2003, the density of target trees in all treatment units combined was 1,544 trees/ha (625 tree/ac) in wire zones and 1,594 trees/ha (645 trees/ac) in border zones. If the handcut unit was omitted from the calculations, then only 340 target trees/ha (138 trees/ac) in wire zones and 501 trees/ha (203 trees/ac) in border zones were present. IVM of a ROW is not a "tree-proof" but rather a "tree-resistant" means of reducing tree invasion. Competition with existing plants and wildlife predation on tree seeds on a ROW managed via the wire­border zone method minimized but did not eliminate tree invasion. Since 1987, IVM and the wire­border zone method of ROW maintenance has increased the time between treatment cycles, thereby reducing labor and chemical costs at the SGL 33 Research and Demonstration Area.

Predation of wildlife by domestic cats Felis catus in Great Britain

ABSTRACT 1. A questionnaire survey of the numbers of animals brought home by domestic cats Felis catus was conducted between 1 April and 31 August 1997. A total of 14 370 prey items were brought home by 986 cats living in 618 households. Mammals made up 69% of the items, birds 24%, amphibians 4%, reptiles 1%, fish < 1%, invertebrates 1% and unidentified items 1%. A minimum of 44 species of wild bird, 20 species of wild mammal, four species of reptile and three species of amphibian were recorded. 2. Of a sample of 696 individual cats, 634 (91%) brought home at least one item and the back‐transformed mean number of items brought home was 11.3 (95% CI 10.4–12.2). The back‐transformed means and number of cats retrieving at least one item from each prey group were: 8.1 (7.4–8.9) mammals for 547 (79%) cats, 4.1 (3.8–4.5) birds for 506 (73%) cats, 2.6 (2.2–3.0) herpetofauna for 145 (21%) cats and 2.2 (1.8–2.7) other items for 98 (14%) cats. 3. The number of birds and herpetofauna brought home per cat was significantly lower in households that provided food for birds. The number of bird species brought home was greater in households providing bird food. The number of birds and herpetofauna brought home per cat was negatively related to the age and condition of the cat. The number of mammals brought home per cat was significantly lower when cats were equipped with bells and when they were kept indoors at night. The number of herpetofauna brought home was significantly greater when cats were kept in at night. 4. Based on the proportion of cats bringing home at least one prey item and the back‐transformed means, a British population of approximately 9 million cats was estimated to have brought home in the order of 92 (85–100) million prey items in the period of this survey, including 57 (52–63) million mammals, 27 (25–29) million birds and 5 (4–6) million reptiles and amphibians. 5. An experimental approach should be taken to investigate the factors found by this descriptive survey to influence the numbers of prey brought home by cats. In particular, investigation of potential management practices that could reduce the numbers of wild animals killed and brought home by cats will be useful for wildlife conservation, particularly in suburban areas.

Does fox baiting threaten the spotted-tailed quoll, Dasyurus maculatus?

In Australia, baiting with 1080 (sodium fluoroacetate) is widely used to reduce predation of native wildlife by the red fox. However, such control programs may place some native carnivores at risk, particularly the spotted-tailed quoll in eastern Australia. We measured the mortality in a total of 57 quolls fitted with mortality radio-transmitters during four experimental fox baitings with Foxoff® 1080 baits containing Rhodamine B in north-east New South Wales. In all experiments quolls visited bait stations regularly and removed a total of 20 baits. All but one of these baits was found in the vicinity of the bait station, indicating that quolls did not ingest baits. This was confirmed by the absence of Rhodamine B in the vibrissae of all quolls retrapped after baiting. The only quoll that may have died from a bait had eaten a cached bait some six weeks after baiting concluded. Thus, baiting did not threaten any of the quoll populations sampled. Therefore it appears that most restrictions imposed to protect spotted-tailed quolls during fox baiting are unnecessary as long as this bait type is used.

Bells reduce predation of wildlife by domestic cats (Felis catus)

AbstractTwenty‐one cat owners from a 100 km2 area, centred on Carnforth, Lancashire, England, recorded each dead prey item delivered by their cat or cats during an 8‐week period, following one of three experimental schedules, each of which required each cat to have a bell on a collar for only half of the time. The mean number of items each cat delivered to the owner was 2.9 in the 4 weeks when the cats had a bell attached, compared to 5.5 for the equivalent time when the bell was absent. The bell had no effect on the relative numbers of different prey types delivered, and there was no evidence that the cats adapted their hunting behaviour to reduce the effect of the bell over time.

Factors affecting predation by buzzards Buteo buteo on released pheasants Phasianus colchicus

Summary Information on the effects of wildlife predation on game and livestock is required to allow improved management of all organisms involved. Monitoring of prey, predators and predation mechanisms each suggests important methods, illustrated here by data from common buzzards Buteo buteo and ring‐necked pheasants Phasianus colchicus. Location data from 136 radio‐tagged common buzzards, together with prey remains from 40 nest areas, records from 10 gamekeepers and vegetation surveys, were used to investigate raptor predation at 28 pens from which pheasants were released in southern England. Among 20 725 juvenile pheasants released in 1994–95, gamekeepers attributed 4·3% of deaths to buzzards, 0·7% to owls, 0·6% to sparrowhawks, 3·2% to foxes and 0·5% to other mammals. Fresh pheasant remains were found on 7% of 91 visits to buzzard nests, and 8% of radio‐tagged buzzards had significantly more association than other buzzards with pheasant pens. Predation by buzzards was most likely to be recorded at release pens with little shrub cover, deciduous canopies and a large number of released pheasants. The number of pheasants killed was greatest in large pens with extensive ground cover, and the highest proportion of released pheasants was killed in large pens where few were released. However, only 21% of 55 releases had > 2 pheasant kills per week. Radio‐tagged buzzards were located most often at pheasant‐release pens with open, deciduous canopies. Pens were most likely to be visited by buzzards that had fledged nearby, but the proximity of buzzard nests had little influence on how much predation occurred. Only a minority of buzzards associated frequently with pheasant pens, and predation was heavy at only a minority of sites, where pen characteristics and release factors probably made it easy for individual buzzards to kill pheasants. We suggest that the occasional heavy losses could be avoided by encouraging shrubs rather than ground cover in pens, by siting pens where there are few perches for buzzards, and perhaps also by high‐density releases.

The economic costs of wildlife predation on livestock in Gokwe communal land, Zimbabwe

In areas bordering wildlife reserves in Zimbabwe, agro‐pastoralists suffer livestock depredation by wild carnivores. However, the economic value of these losses, and therefore the levels of compensation required has never been calculated. Between January 1993 and June 1996 in a 33‐km2 area of Gokwe communal land bordering the Sengwa Wildlife Research Area, 241 livestock were killed by wild carnivores. Baboons (Papio ursinus Kerr), lions (Panthera leo Linnaeus) and leopards (P. pardus Linnaeus) were the most serious predators, contributing 52%, 34% and 12% of kills, respectively. Baboons only killed young goats (Capra hircus Linnaeus) and sheep (Ovis aries Linnaeus) by day, while lions and leopards jumped into fortified kraals at night and killed cattle (Bos indicus Linnaeus), donkeys (Equus asinus Linnaeus) and smallstock. In 1995, predators killed 5% of livestock holdings, double that recorded by other African studies. The annual total value of losses depended upon the degree of lion predation on the most valuable species, cattle and donkeys. The average annual loss per livestock‐owning household was US$13, or 12% of each household's net annual income. Losses could be reduced by improving kraal defences against lion and leopard predation in the dry season, when attacks were most common.

Transmission of Feline Immunodeficiency Virus in a population of cats (Felis catus)

The increasing awareness of the ecological impact of domestic cats (Felis catus) as wildlife predators has given rise to much effort in research on cat control, but studies related to the spread of pathogens in natural populations remain almost non-existent. We aimed to determine the infection strategy of Feline Immunodeficiency Virus (FIV) in a natural population of cats, focusing on qualitative and quantitative aspects of its transmission. FIV is a lethal retrovirus infecting cats world-wide, transmitted by bites. It has an interesting potential as a control agent for this species. We studied an urban population of stray cats over three years, monitoring its epidemiology and its social and spatial structures. Despite a high cat density, both transmission rate and prevalence of FIV were relatively low. Socially dominant males were more likely to be infected. In addition, males of the study population were less often infected than in another population, where a polygynous mating system involved more fights. Infected individuals lived long enough to acquire the virus and infect another cat. Because they were subordinates, non-infected cats had a shorter life expectancy, which would not have permitted the spread of FIV. Thus, FIV infected predominantly at-risk individuals whose social ranking allowed a high probability of retransmitting the virus.

Control of Urban Wildlife Predation by Cats Through Public Education

Control of Urban Wildlife Predation by Cats Through Public Education