European rabbit (Oryctolagus cuniculus)
Ecosystem Engineering
The designation ecosystem engineering was coined by Jones et al. (1994) to refer to the organisms responsible for major habitat changes, not only of them but for other species. All species interact with their physical environment but some organisms substantially influence environmental conditions and resource availability affecting other species and consequently the attributes of natural species assemblages.
It is easy to imagine that large species like elephants can easily modify the environment. In fact, elephants are also considered ecosystem engineers because their impact highly affects other species lives. They can easily put trees down and originate clear patches within forested areas, for instance.
But this has nothing to do with size. In fact, perhaps the most classic example is the beaver that not only alters the river-flow patterns but also the surrounding vegetation and the nutrient cycle (Naiman et al. 1994).
Why is the European rabbit considered an Ecosystem Engineer?
First of all, I must say I’m focusing on European rabbit’s role on its native area and not in the locations where it was introduced and became a pest. Despite its current wide distribution, the European rabbit is native of the Iberian Peninsula and is adapted to the Mediterranean landscapes formed by a mosaic of agriculture, open lands and bushes.
Rabbits are special among leporids because they form colonies that may reach high densities (Gibb 1990). Living in large groups, an everyday task may turn into something meaningful regarding the environment.
- Digging ability
Rabbits dig large warrens that can provide refuge areas for many other species (Delibes-Mateos et al. 2008). Amphibians, reptiles, mammals, and some birds frequently use rabbit warrens. Blázquez and Villafuerte (1990) observed the Montpellier snake (Malpolon monspessulanus) nesting inside rabbit warrens. Gálvez Bravo et al. (2009) found that lizards were positively associated with burrows, and that burrows determined lizard presence at otherwise unfavourable habitats. Small mammals like the garden dormouse (Eliomys quercinus) or the wood mouse (Apodemus sylvaticus) have been found inside rabbit warrens. Even Eurasian badgers (Meles meles) often construct their diurnal resting dens by enlarging existing rabbit warrens (Revilla et al. 2001)
- Soil fertility
Rabbit use latrines for communication and for territory marking. Because they serve a social function, latrines can be used for a number of years (Gibb 1993) and its use can be very high when rabbits are abundant. Rabbit fecal pellets have N and P content comparable to the dung of stock animals. For that reason, latrines have a clear effect on soil fertility and consequently on plant growth (Willot et al. 2000). Rabbits import nutrients to latrines which locally create diversity in the Mediterranean ecosystems (Petterson 2001).
- Grazing impact
Rabbits are herbivore and because they live in colonies, they can alter significantly the vegetation in the area. Some studies have been undertaken in the Iberian Peninsula but I highlight the results obtained by Rueda (2006) in Central Spain: rabbits eat 42% of the total aboveground biomass, equivalent to 80% of the biomass consumed by all vertebrate herbivores in the area. In locations where rabbits are abundant, they influence greatly the effects on the flow of energy and materials, so excluding them from the ecosystem would cause marked changes in the plant communities (García-Fuentes et al. 2006).
But they don’t just eat…
They are selective and that causes a difference in the abundance of herbaceous species. Those they tend to eat decrease the abundance and those they don’t like tend to maintain or increase their numbers (García-Fuentes et al. 2006). So rabbits are also shaping the vegetation and their action promotes the maintenance of open scrubland, which is their preferred habitat (Moreno and Villafuerte 1995). They are indirectly benefiting several species of small mammals whose preferred habitat is similar.
This are some of the reasons of why rabbits are so important around here.
I'll cover additional ones in future posts.
References
Blázquez MC, Villafuerte R (1990) Nesting of the Montpellier snake (Malpolon monspessulanus) inside rabbit warrens at Doñana National Park (SW Spain): phenology and a probable case of communal nesting. Journal of Zoology 222:692–693.
Delibes-Mateos M, Delibes M, Ferreras P, Villafuerte R (2008) Key Role of European Rabbits in the Conservation of the Western Mediterranean Basin Hotspot. Conservation Biology 22:5
Gálvez Bravo L, Belliure J, Rebollo S (2009) European rabbits as ecosystemengineers: warrens increase lizard density and diversity. Biodiversity and Conservation 18: 869.
García-Fuentes A, Muñoz-Rodríguez JJ, Cano-Carmona E (2006) Alteraciones florísticas en los pastizales sometidos a altas densidades de conejos. Revista del Colegio Oficial de Biólogos de Andalucía 5: 2-5.
Gibb JA (1990) The rabbit, Oryctolagus cuniculus. Pages 116–120 in J. A. Chapman and J. E. C. Flux, editors. Rabbit, hares and pikas: status survey and conservation action plan. IUCN/SCC Lagomorph Specialist Group, Information Press, Oxford, United Kingdom.
Gibb JA (1993) Sociality, time and space in a sparse population of rabbits (Oryctolagus cuniculus). Journal of Zoology 229:581–607.
Jones CG, Lawton JH, Shachack M (1994) Organisms as ecosystem engineers. Oikos 69:373–386
Moreno S, Villafuerte R (1995) Traditional management of scrubland for the conservation of rabbits Oryctolagus cuniculus and their predators in Doñana Nacional Park, Spain. Biological Conservation 73:81–85.
Naiman RJ, Pinay G, Johnston CA, Pastor J (1994) Beaver influences on the long term biogeochemical characteristics of boreal forest drainage networks. Ecology 75:905-921.
Petterson, DA (2001) The effects of the European rabbit (Oryctolagus cuniculus) on soils and vegetation in semi-arid, south-eastern Spain. PhD thesis. University of Leeds, Leeds, United Kingdom.
Revilla E, Palomares F, Fernández N (2001) Characteristics, location and selection of diurnal resting dens by Eurasian badgers (Meles meles) in a low density area. Journal of Zoology 255:291–299.
Rueda M (2006) Selección de hábitat por herbívoros de diferente tamaño y sus efectos sobre la vegetación. PhD thesis. Universidad de Alcalá, Alcalá de Henares, Spain.
Willott S, Miller A, Incoll L, Compton DG (2000) Biology and Fertility of Soils 31: 379.
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