Study of territorial behaviour and stress for the improvement of European wild rabbit restocking programs

The European rabbit (Oryctolagus cuniculus L.) is a keystone species that is native to the Iberian Peninsula and whose populations have undergone a dramatic decline in abundance in their natural ranges throughout the second half of the 20th century. The economic and ecological importance of the wild rabbit has now led to the need to perform management actions aimed at boosting the remaining populations and establishing new ones, particularly in Mediterranean areas. Restocking actions are one of the handiest management tools, and scientific research whose objective is to define and solve the major methodological problems is abundant in literature. However, the majority of research has focused on factors which are extrinsic to wild rabbits, such as predation, diseases and habitat, while neglecting other factors that are intrinsic to wild rabbit biology. The principal aim of this PhD thesis is to improve the efficiency of wild rabbit restocking programs by taking into account intrinsic aspects of rabbit biology such as social behaviour and stress. In order to do so, I have performed five experiments whose intention has been to test Fecal Near Infrared Reflectance Spectroscopy and indigestible faecal markers as cheap, easy, user-friendly and non-invasive tools by which territorial marking by wild rabbits can be studied; I have also measured restocked wild rabbit populations’ responsiveness to acute stressors in a non-invasive manner as a predictor of population growth during the breeding season; I have additionally studied the density-dependence phenomenon inside wild rabbit restocking plots, with the aim of providing a better management of these plots and improving their efficiency as extensive breeding sites; and finally, I have performed a supplementary experiment with wild-type rats with the intention of attaining a better understanding of the relationship between physiological stress and territorial behaviour. The first four chapters are framed..

The high abundance of wild ungulates in a mediterranean region: is this compatible with the European rabbit?

This is an Open Access article.The landscape in southern Iberia has, over the last four decades, altered as a result of the land abandonment, while the abundance of wild boar Sus scrofa and red deer Cervus elaphus has simultaneously increased, and some key prey species such as the European rabbit Oryctolagus cuniculus have declined. In this work we explore: 1) the relationships between big game species (red deer and wild boar) and rabbit abundance, and 2) whether these relationships could have effects on food quality (total nitrogen available in the pasture and percentage of leguminosae) and food availability of (herbaceous cover). We therefore selected nine big game estates with a range of abundance as regards ungulates and similar Mediterranean habitat. Wild boar abundance was statistically negative in relation to rabbit abundance, while no significant statistical relationships between rabbit abundance and habitat structure and forage quality were evidenced. However, wild boar abundance, but not that of red deer, was negatively associated with leguminosae cover, and the percentage of surface rooted by wild boar was negatively associated with the percentage of herbaceous cover. Overall, our results suggest that the abundance of wild boar is negatively related to that of rabbits, and could have a negative effects on rabbit abundances by food competition as a result of: 1) a decrease in herbaceous coverage and leguminosae in the pasture and 2) an increase in the total percentage of soil disturbed as a result of rooting.We should like to thank to the Andalucía Autonomous Government’s Environmental Council for financing this work via a project to improve the habitat of the black vulture in Córdoba province.Peer Reviewe

Efecto de la densidad de ungulados silvestres sobre los invertebrados en un ecosistema Mediterráneo

[EN]: Effect of wild ungulate density on invertebrates in a Mediterranean ecosystem.— In recent decades, the abundance and distribution of certain big game species, particularly red deer (Cervus elaphus) and wild boar (Sus scrofa), have increased in south central Spain as a result of hunting management strategies. The high density of these ungulate species may affect the abundance of epigeous invertebrates. We tested the relationships between big game abundance and biodiversity, taxon richness, the biomass of invertebrates and their frequency on nine hunting estates and in comparison to ungulate exclusion areas. Ungulate exclusion itself affected invertebrate richness, since lower values were found in the open plots, whereas the highest differences in invertebrate diversity between fenced and open plots was found in areas with high wild boar density. Where wild boar densities were high, the number of invertebrates decreased, while where they were low, red deer had a positive effect on invertebrate abundance. Fenced plots thus seemed to provide refuge for invertebrates, particularly where wild boar were abundant. This study supports the idea that the structure of fauna communities is damaged by high density populations of ungulates, probably due to decreased food availability owing to overgrazing, modified conditions of ecological microniches and direct predation. However, the effects depended on the group of invertebrates, since saprophytic species could benefit from high ungulate abundance. Our findings reflect the need to control ungulate population density under Mediterranean conditions in south-western Europe and to implement ungulate exclusion plots.[ES]: En las últimas décadas, la abundancia y distribución de determinadas especies de caza mayor, especialmente el ciervo rojo (Cervus elaphus) y el jabalí (Sus scrofa), han aumentado en la zona centromeridional de España como resultado de las estrategias de gestión cinegética. La alta densidad de estas especies de ungulados puede afectar a la abundancia de los invertebrados epigeos. Estudiamos la relación entre la abundancia de las especies de caza mayor y la biodiversidad, la riqueza de taxones, la biomasa de invertebrados y su frecuencia en nueve fincas de caza, y se comparó con las zonas de exclusión de ungulados. De por sí, la exclusión de ungulados afectó a la riqueza de invertebrados, ya que se encontraron valores más bajos en las parcelas abiertas, mientras que las mayores diferencias en la diversidad de invertebrados entre parcelas abiertas y cercadas se encontraron en zonas con una alta densidad de jabalíes. Donde la densidad de jabalíes era alta, el número de invertebrados disminuyó, mientras que donde era baja, el ciervo rojo tuvo un efecto positivo en la abundancia de invertebrados. Así, las parcelas cercadas parecían ofrecer refugio a los invertebrados, sobre todo donde los jabalíes eran abundantes. Este estudio apoya la idea de que las poblaciones con una alta densidad de ungulados perjudican a la estructura de las comunidades faunísticas, probablemente debido a la disminución de la disponibilidad de alimentos como consecuencia del sobrepastoreo, la modificación de las condiciones de los micronichos ecológicos y la depredación directa. Sin embargo, los efectos dependieron del grupo de invertebrados, ya que las especies saprofitas podrían beneficiarse de la alta abundancia de ungulados. Nuestros resultados reflejan la necesidad de controlar la densidad de las poblaciones de ungulados en condiciones mediterráneas en el suroeste de Europa y de establecer parcelas de exclusión de ungulados.We are grateful to the estate keepers for their hospitality and assistance in the field work, and to the Andalucía Autonomous Government’s Environmental Council for financing this work via a project to improve the habitat of the black vulture in Córdoba province, thanks to which we have been able to carry out this work.Peer Reviewe

Factors affecting wild rabbit production in extensive breeding enclosures: how can we optimise efforts?

[EN] The declining rabbit population in the Iberian Peninsula has led hunters and authorities to rear rabbits in captivity systems for their subsequent release. One alternative method to intensive rabbitry systems is the use of extensive breeding enclosures, since they produce animals of greater quality for hunting and conservation purposes. However, some of the factors that affect rabbit production in breeding enclosures are still unknown. The present study used partial least squares regression (PLSR) to analyse the effects of plot size, scrub cover, slope, initial rabbit abundance, the resources needed to dig warrens, predation and proximity to other enclosures on rabbit abundance. The results of our study show a positive effect of the number of other fenced plots within a radius of 3 km, a positive relationship with the availability of optimal resources for building warrens and a positive influence of intermediate values of scrub cover. According to our results, to maximise rabbit production in the enclosures it would be advisable to concentrate the restocking effort by ensuring that the restocking plots are close to each other, thus avoiding isolated enclosures. Furthermore, the selection of plots with an appropriate scrub cover and high availability of elements that favour the construction of warrens, such as large stones, sloping land or tall shrubs, may optimise results.We would like to thank S. Crespo for her help during data collection; S. Newton for reviewing the English, and I.C. Barrio for her statistical assistance. The staff of the Andalusia Environmental Government provided logistical and technical support. The Andalusia Environmental Government funded this work through a project for the conservation of the Black Vulture in Cordoba province.Guerrero-casado, J.; Ruiz-aizpurua, L.; Carpio, AJ.; Tortosa, FS. (2013). Factors affecting wild rabbit production in extensive breeding enclosures: how can we optimise efforts?. World Rabbit Science. 21(3):193-199. doi:10.4995/wrs.2013.1259.SWORD19319921

Acute and lasting effects of single mineralocorticoid antagonism on offensive aggressive behaviour in rats

<p>Aggression is a major component of territorial behaviour. However, different mechanisms evolved to fulfil the defence function while reducing the cost derived from agonistic interactions, as a differential response to the same stimulus, depending on the outcome of past conflicts - priming, which makes the aggressive response adaptable. Aggressive behaviour is facilitated by the stress response, so, we tested the effect of a single injection of a mineralocorticoid antagonist (spironolactone) on the escalation of territorial aggression in a resident-intruder paradigm, and its modulation by social stimulus. We used naive Wild Type Groningen - WTG - rats as residents, and naive and previously defeated Wistar rats as intruders. The first encounter was 1 h after the injection, and then repeated in 3 consecutive days. When WTG rats were confronted with naive Wistar rats, single injections of spironolactone completely abolished the attack behaviour in the short term while enhancing it in the long term. When we used defeated Wistar rats, the spironolactone effect was not as great. The short-term reduction in aggressive behaviour was attributable to the blockade of mineralocorticoid receptors during the first encounters, while the enhancement in aggressive behaviour in the long term was suggested to be related to the imbalance between mineralocorticoid and glucocorticoid receptors during the stress response associated to the encounters. (C) 2013 Elsevier B.V. All rights reserved.</p>