Feral Goats Capra Hircus Research Articles

Sex-driven neighborhood effects on herbivory in the dioecious Mediterranean palm Chamaerops humilis L.

Although it is well recognized that the strength of plant-herbivore interactions can vary with the plant sex, the distance, and the density of conspecific neighbors, no study has yet assessed their combined influence. Here, we filled this knowledge gap by focusing on the dioecious palm Chamaerops humilis L., and its two main herbivores, the invasive moth Paysandisia archon Burmeister and the feral goat Capra hircus L. We evaluated levels and spatial patterns of herbivory, as well as those of plant size and number of inflorescences in two palm populations in Mallorca (Balearic Islands, Spain). Our spatial point pattern analyses revealed that palms not affected by moth herbivory or goat florivory were spatially aggregated, goats fed more strongly upon inflorescences in palms with more neighbors, but they consumed more leaves in isolated palms. Interestingly, we could reveal for the first time that plant sex is a key plant trait modulating neighborhood effects. For instance, whereas aggregated female palms experienced lower intensity of goat florivory than isolated ones, male palms showed the opposite pattern. Palm size and number of inflorescences also showed sex-related differences, suggesting that sexual dimorphism is a key driver of the observed neighborhood effects on herbivory. Our study highlights the importance of considering relevant plant traits such as sex when investigating plant neighborhood effects, calling for further research to fully understand the dynamics governing plant-herbivore interactions in dioecious systems.

From seed dispersal service to reproductive collapse: density‐dependent outcome of a palm–mammal interaction

Interspecific ecological interactions are inherently context‐dependent. They may vary in both magnitude and sign depending on the biotic and abiotic conditions, depicting a mutualism–antagonism continuum. However, how population abundances and the activity of interacting species modulate these interactions remains underexplored. Here, we chose the interaction between the Mediterranean palm Chamaerops humilis and the feral goat Capra hircus in Mallorca (Balearic Islands, Spain). We selected three study plots with low, intermediate and high intensities of goat activity where we characterized palm distribution, seed rain, seed predation and early palm recruitment during two consecutive years. Since goats can cause both costs (e.g. florivory) and benefits (e.g. seed dispersal) to C. humilis performance, we investigated the following three questions: 1) does the spatial distribution of adult palms vary depending on the intensity of goat activity? 2) Does the intensity of goat activity influence seed rain and its potential spatial association with adult palms? 3) To what extent does the intensity of goat activity determine post‐dispersal events such as seed predation and seedling emergence? We found that adult palms showed a more clumped and complex distribution (double‐cluster process) in plots with low and intermediate goat activity compared to that with high goat activity (simple‐cluster process). In the low goat activity plot, dispersed seeds were spatially aggregated around adult palms, showing twice as much insect‐seed predation and nearly three times lower seed germination success than those in the intermediate goat activity plot. Palm seed dispersal and recruitment were almost nil in the high goat activity plot due to heavy consumption of palm inflorescences and developing fruits by goats. Our findings demonstrate how the net outcome of plant–animal interactions can change from mutualism to antagonism, from reproductive service to reproductive collapse, depending on the abundance and the activity of the interacting species.

A review of mammal eradications on Mediterranean islands

Abstract Impacts of alien invasive species on island communities and ecosystems may be even more detrimental than on the mainland. Therefore, since the 1950s, hundreds of restoration projects have been implemented worldwide, with the aim of controlling or eradicating alien species from islands. To date, no review has been focused on eradication on Mediterranean islands. To fill the gap, I reviewed the available information concerning mammal eradications so far carried out on Mediterranean islands, examining the details of several aspects of project implementation and monitoring. I obtained data for 139 attempted eradications on 107 Mediterranean islands in eight countries, with Greece, Italy, and Spain accounting for the highest number. Eradication projects targeted 13 mammal species. The black rat Rattus rattus was the target of over 75% of the known attempted eradications in the Mediterranean Basin; other species targeted were feral goat Capra hircus, house mouse Mus musculus, European rabbit Oryctolagus cuniculus, and domestic cat Felis catus. The most widely adopted technique was poisoning (77% of all eradications), followed by trapping (15%) and hunting (4%). However, techniques were largely target‐specific. The average failure rate was about 11%. However, this percentage varied according to the specific mammalian order, and eradications of Carnivora failed more often than those of other mammals. Among rodents, house mouse eradication attained a very high failure rate (75%). Reinvasion occurred after 15% of successful eradications. A better understanding of the motivations of animal rights activists may improve the chance of success when eradicating charismatic or domesticated species. Furthermore, it is crucial to collect data and case studies about reinvasions, in order to strengthen biosecurity programmes following eradication. As in other parts of the world, the next frontier in alien mammal management on Mediterranean islands concerns the eradication of invasive species from inhabited islands.

Adaptive management of an iconic invasive goat Capra hircus population

AbstractWe describe the first use of fertility control to manage a free‐living mammal population in Europe. An immunocontraceptive vaccine (GonaCon) was used to reduce female fertility in an invasive feral goat Capra hircus population. Adaptive management was implemented to assess the feasibility of fertility control and to allow prediction of the required level of vaccination to limit goat numbers. The individual probability of breeding success decreased for two years following treatment. Understanding the population demographics alongside modelling of the individual and population‐level responses to the vaccine is important for future management.

Monitoring ungulates in steep non-forest habitat: a comparison of faecal pellet and helicopter counts

Faecal pellet counts have been widely used to monitor the abundances of introduced ungulates in New Zealand, but ground-based sampling cannot be conducted safely in the steep non-forest habitats that are common in New Zealand's Southern Alps. Helicopter counts may be an effective technique for monitoring ungulates in steep non-forest habitat. We evaluated the relationship between faecal pellet and helicopter counts of ungulates (primarily feral goat Capra hircus) at 12 non-forest sites in the Southern Alps. Within each site we counted the numbers of ungulates from a helicopter on three occasions and the number of intact faecal pellets along 30 transects. Mean observed densities of feral goats derived from helicopter counts ranged from 0.0 to 20.2 km−2. There was a positive curvilinear (concave down) relationship between faecal pellet and helicopter counts. Compared with faecal pellet counts, helicopter counts were cheaper, could identify ungulate species and provided estimates of absolute density. Helicopter counts are a cost-effective method for monitoring ungulates in the steep non-forest habitats of New Zealand's Southern Alps.

Changes in wild ungulate populations in Aragon, Spain between 2001 and 2010

To update the information on the distributions of wild ungulates in Aragon, Spain, populations were surveyed based on questionnaires sent to rangers of the Government of Aragon. The data were analyzed in two five-year periods: 2001-2005 and 2006-2010. Our analysis was based on the 242 and 278 questionnaires, corresponding approximately with 80-90% answers that were analyzed in 2006 and 2011, respectively. The survey documented the presence/absence of up to eight wild ungulate species within a UTM 10x10 km grid on maps that were specific to the counties in which the rangers worked. In 2006-2010, wild boar Sus scrofa was the most widely distributed species as it occurred in all of the grid blocks. Roe deer Capreolus capreolus were documented in 89% of the grid blocks, Iberian wild goat Capra pyrenaica in 37%, red deer Cervus elaphus in 31%, Pyrenean chamois Rupicapra p. pyrenaica in 10%, feral goat Capra hircus in 8%, fallow deer Dama dama in 3%, and mouflon Ovis aries in 0.3%. The Pyrenees had the highest and the Middle Ebro Valley had the lowest diversity of ungulates. In the Iberian System, diversity was intermediate. Overall, the distribution of ungulates increased 21% between the two periods. Feral goat populations expanded the most (111%), although Iberian wild goat (61%), roe deer (50%), and red deer (4%) also expanded. The range of wild boar populations remained stable, but the ranges of chamois and fallow deer populations were reduced 6%. By 2010, typically, in most block grids three or more species of wild ungulates coexist. We recommend that ungulate populations in Aragon be surveyed at least every five years.

Size and density of a feral goat Capra hircus population in a protected area in the Pyrenees

To estimate the number and density of feral goats Capra hircus in Guara Nature Park (Pyrenees, Spain), 30 observation points were established throughout a 440-km2 portion of the park occupied by goats. In April and May, 2009, goats were counted daily during 3-h observation periods that began at dusk. The counts documented 282 goats in 39 groups. Their locations were mapped and, to calculate the area occupied by the groups, the data were analysed using ArcInfo, which indicated that the total visual area was 8,075 ha. Based on Distance Sampling, the estimated density was 2.1 goats km2 (CV 32%), which implied a population of about 940 individuals. That sub-population is part of a larger population in the southern Pyrenees that s distributed over an area of at least 2,100 km2 and, probably, is one of the largest populations in continental Europe. In the Pyrenees feral goats might be an important food resource for the endangered Golden Eagle Aquila chrysaetos. The conservation, control, or eradication of those goats should be based on a comprehensive analysis of its role in the ecology of the Pyrenees.

Abundance and management of Mariana Fruit Bats and feral ungulates on Anatahan, Mariana Islands

A survey of Mariana Fruit Bats Pteropus mariannus and feral ungulates was conducted on Anatahan, Mariana Islands, in July 1995. We estimated that a population of 1 902-2 136 bats persists on the island, based on a combination of direct colony counts, departure counts, and station counts of non-colonial animals. Our data suggest that bat numbers have declined since the last surveys were made in 1983 and 1984. We located seven colonies, which held approximately 85-92% of the total population. Most colonies and foraging animals were associated with native forest or isolated native trees in other habitats. Bats fed on five species of plants, with the fruit of Pandanus tectorius eaten most frequently. Anatahan supports a very large Feral Goat Capra hircus population estimated at roughly 5 000-6 000 animals. Feral Pigs Sus scrofa are less common. Both species cause severe damage to plant communities of the island. We recommend that a legal hunting programme for fruit bats be deferred until 1) population censuses on neighbouring islands are completed and it is determined that bat populations can sustain harvesting, 2) habitat degradation is reversed through the control of feral animals, and 3) illegal hunting is curtailed.