Can foxes be controlled by reducing their fertility?

Pech, Roger P.; Hood, G. M.; McIlroy, John; Saunders, Glen

doi:10.1071/r96059

Cited by 47 publications

(41 citation statements)

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“…Virus-vectored immunocontraception (VVIC), for example, utilises a species-specific virus to disseminate this vaccine through a pest population by placing the gene encoding the reproductive protein into the genome of the virus (Tyndale-Biscoe, 1994). This potentially powerful new technique would be used mainly for rodents and small herbivores, such as rabbits and possums (Cowan, 1996;Rodger, 1997;Smith, Walmsley & Polkinghorne, 1997), but also could be very efficient for small carnivores as well (Bradley et al, 1997;Pech et al, 1997;Verdier et al, 1999;Courchamp & Cornell, 2000).…”

Section: (B ) Decreasing the Reproduction Of Alien Mammalsmentioning

confidence: 99%

Mammal invaders on islands: impact, control and control impact

Courchamp¹,

Chapuis²,

2003

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The invasion of ecosystems by exotic species is currently viewed as one of the most important sources of biodiversity loss. The largest part of this loss occurs on islands, where indigenous species have often evolved in the absence of strong competition, herbivory, parasitism or predation. As a result, introduced species thrive in those optimal insular ecosystems affecting their plant food, competitors or animal prey. As islands are characterised by a high rate of endemism, the impacted populations often correspond to local subspecies or even unique species. One of the most important taxa concerning biological invasions on islands is mammals. A small number of mammal species is responsible for most of the damage to invaded insular ecosystems : rats, cats, goats, rabbits, pigs and a few others. The effect of alien invasive species may be simple or very complex, especially since a large array of invasive species, mammals and others, can be present simultaneously and interact among themselves as well as with the indigenous species. In most cases, introduced species generally have a strong impact and they often are responsible for the impoverishment of the local flora and fauna. The best response to these effects is almost always to control the alien population, either by regularly reducing their numbers, or better still, by eradicating the population as a whole from the island. Several types of methods are currently used : physical (trapping, shooting), chemical ( poisoning ) and biological (e.g. directed use of diseases ). Each has its own set of advantages and disadvantages, depending on the mammal species targeted. The best strategy is almost always to combine several methods. Whatever the strategy used, its long-term success is critically dependent on solid support from several different areas, including financial support, staff commitment, and public support, to name only a few. In many cases, the elimination of the alien invasive species is followed by a rapid and often spectacular recovery of the impacted local populations. However, in other cases, the removal of the alien is not sufficient for the damaged ecosystem to revert to its former state, and complementary actions, such as species re-introduction, are required. A third situation may be widespread : the sudden removal of the alien species may generate a further disequilibrium, resulting in further or greater damage to the ecosystem. Given the numerous and complex population interactions among island species, it is difficult to predict the outcome of the removal of key species, such as a top predator. This justifies careful pre-control study and preparation prior to initiating the eradication of an alien species, in order to avoid an ecological catastrophe. In addition, long-term monitoring of the post-eradication ecosystem is crucial to assess success and prevent reinvasion.

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Section: (B ) Decreasing the Reproduction Of Alien Mammalsmentioning

confidence: 99%

Mammal invaders on islands: impact, control and control impact

Courchamp¹,

Chapuis²,

2003

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“…Sterilization has been discussed as a wildlife management tool (Garrott 1995) in many contexts, including control of rabies (Linhart and Enders 1964) and limiting the distribution and numbers of animals such as feral horses (Kirkpatrick et al 1990), geese (Branta canadensis) (Converse and Kennelly 1994), deer (Odocoileus virginianus) (Matschke 1977;Plotka and Seal 1989), burros (Turner et al 1996), and red foxes (Vulpes vulpes) (Linhart and Enders 1964;Oleyar and McGinnes 1974;Pech et al 1997). However, the effect of sterilization on wild carnivore behavior has not been widely investigated (Asa 1995).…”

Section: Introductionmentioning

confidence: 99%

Effects of sterilization on territory fidelity and maintenance, pair bonds, and survival rates of free-ranging coyotes

Bromley¹,

Gese²

2001

Can. J. Zool.

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Predation on sheep by coyotes (Canis latrans) is a longstanding problem for sheep producers. Current research suggests that surgical sterilization of coyotes could prove to be an effective method of reducing their depredation rates on domestic sheep by modifying their predatory behavior. However, for sterilization to be a viable management tool, the territorial and affiliative behaviors of pack members would need to remain in place. We tested whether surgically sterilized coyotes maintained pair bonds and territories in the same manner as intact coyotes. We also examined if territory fidelity and survival rates differed between sterile and intact coyotes. From June 1997 to April 2000, 10 males and 9 females were sham-operated and radio-collared, while 20 males and 6 females were surgically sterilized and radio-collared. We monitored members of 5 sterile and 4 intact packs during 1998, 6 sterile and 7 intact packs during 1999, and 4 sterile and 6 intact packs through the 2000 breeding season. Behaviorally, sterile packs appeared to be no different than intact packs. A half-weight association index showed that social dyads within sterile coyote packs were located together as frequently as dyads within intact packs. Simultaneous radiolocations of members of sterile packs showed that members of sterile packs were significantly closer to each other than would be expected from random locations. There was no difference in size or degree of overlap between territories of sterile and shamoperated coyote packs. Sterile coyotes had a higher annual survival rate than reproductive animals in 2 of the 3 years, and there was no difference in the level of territory fidelity. We concluded that surgical sterilization did not modify the territorial or affiliative behaviors of free-ranging coyotes, and therefore sterile coyotes could be used as a management tool to exclude other potential sheep-killing coyotes.Résumé : La prédation opérée sur les moutons par les Coyotes (Canis latrans) est un problème de longue date pour les éleveurs de moutons. Des recherches récentes indiquent que la stérilisation chirurgicale des coyotes pourrait être une façon efficace de diminuer les taux de prédation exercée sur les moutons domestiques car elle modifie le comportement prédateur des coyotes. Cependant, pour que la stérilisation soit un outil de gestion efficace, il faudrait que les comportements territoriaux et les comportements d'affiliation restent les mêmes. Nous avons vérifié si les coyotes stéri-lisés par chirurgie sont capables de maintenir la fidélité à un territoire et les liens entre deux individus aussi bien que les coyotes témoins. Nous avons également vérifié si la fidélité au territoire et les taux de survie diffèrent chez les coyotes stérilisés et les coyotes intacts. De juin 1997 à avril 2000, nous avons procédé à des opérations simulées sur 10 mâles et 9 femelles et stérilisé vraiment 20 mâles et 6 femelles et nous avons muni tous ces animaux d'un collier émetteur. Nous avons suivi ainsi 5 meutes stériles et 4 intactes en 1998, ...

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“…Determining the reproductive performance of fox (Vulpes vulpes) is of great interest because such data are needed for management decisions and population modelling (Llyod et al 1976;Vos 1994;Villafuerte et al 1996;Pech et al 1997;Chautan et al 2000;Marlow et al 2000;Harding et al 2001;McIlroy et al 2001). Since uteri from all categories of females are readily obtained from hunters and trappers; placental scars are often the best source of information on fox reproduction.…”

Section: Introductionmentioning

confidence: 99%

Reproduction of the red fox Vulpes vulpes in western France: does staining improve estimation of litter size from placental scar counts?

Ruette

Albaret

2010

Eur J Wildl Res

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We tested a staining method on uteri for counting placental scars on red fox. We estimated reproduction parameters on 358 females collected in three study areas in western France from 1st February 2002 to 31st January 2005. Placental scars (n=103) were described by macroscopic examinations using the following variables: (1) the width and (2) the aspect of placental scars, (3) the abundance of macrophages or the presence of blood, (4) the presence of swellings, (5) the presence and colour of a central band and (6) the presence and colour of lateral bands. A factorial correspondence analysis showed strong associations between the month when scars were examined and categories of variables. Staining on placental scars made macrophages more visible, facilitating identification of 'active' placental scars, i.e. related to the last pregnancy. However, distinction between placental scars due to earlier pregnancies and resorptions was not possible. The staining method used provides a standard that could be useful for obtaining comparable and repeatable results. The mean number of placental scars was 4.85±1.46 (n=103) per vixen. The mean number of embryos per vixen was 4.66± 1.35 (n=68) for yearlings and 5.53±1.50 (n=96) for older females. Including percentages of barren vixens, the total population productivity was significantly smaller for yearlings (3.62±1.86, n=158) than for older females (4.28± 1.75, n=186). We discuss these results in relation to fox densities, culling and food availability.

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Can foxes be controlled by reducing their fertility?

Cited by 47 publications

References 0 publications

Mammal invaders on islands: impact, control and control impact

Mammal invaders on islands: impact, control and control impact

Effects of sterilization on territory fidelity and maintenance, pair bonds, and survival rates of free-ranging coyotes

Reproduction of the red fox Vulpes vulpes in western France: does staining improve estimation of litter size from placental scar counts?

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