Browsing by Subject "South-eastern Spain"

Now showing 1 - 4 of 4
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    Eurasian eagle owls Bubo Bubo adjust nest food stores to nestling age
    (BioOne Digital Library, ) Puche Gómez, Sara; Perales Pacheco, Pablo; Botella, Francisco; Sánchez-Zapata, José Antonio; Pérez-García, Juan Manuel; Gómez Ramírez, Pilar; Ciencias Sociosanitarias
    Some bird species, particularly owls, store prey within their nests during the breeding season. Food storage has been explained by the need to buffer the environmental variability of resources available for the offspring. This study describes food stores of the Eurasian Eagle Owl Bubo bubo in the southeast of the Iberian Peninsula and evaluates which intrinsic and extrinsic factors influence their presence and composition. Between 2003 and 2021, we studied the presence, abundance, biomass and species richness of prey in food stores found in 318 nests. Stores occurred in 63.5% of nests and included 520 prey items belonging to 23 different species. The main prey species was the European Rabbit oryctolagus cuniculus (71.43%). The greatest abundance of prey and biomass found in the stores occurred when the owlets were between 20 and 25 days old, that is when peak owlet growth occurs. Neither abundance nor biomass of prey in stores were related to brood size. Similarly, the frequency of food store occurrence in nests per year was unrelated to precipitation in the preceding months, which serves as a proxy of rabbit abundance. Globally these results support the hypothesis of that Eagle Owl parents adjust the stores according to when their owlets have their highest energy demands, irrespective of brood size and likely prey abundance. Food storage may help Eagle Owls to maximise their reproductive success in a semi-arid environment subject to high environmental variability.
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    Postfire regeneration of a thermomediterranean shrubland area in south-eastern Spain
    (Murcia: Universidad de Murcia, Servicio de Publicaciones, 2003) Götzenberger, Lars; Ohl, Constanze; Hensen, Isabell; Sánchez Gómez, Pedro; Sin departamento asociado; Facultad de Biología
    Postfire regeneration of thermomediterranean shrublands burnt in 1998 was studied in the Province of Murcia (SE Spain). The vegetation struc ture of sites with different exposures was compared with that of adja cent unburnt areas. Three years after the fire, the mean vegetation cover of the burnt sites was still significantly lower than that of the non-burnt areas. However, the results of a Detrended Correspondence Analysis indicate that fires induce only minor changes in the species composi tion and the vegetation structure. Fire seems to be a common pheno menon, and the dominant species are characterized by pre-adaptatio ns to withstand fires. The most frequent pre-adaptation is the ability to resprout rapidly from subterranean parts, whereas the regeneration from seeds is clearly less important in the most dominant species.
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    Seed predation by ants in south-eastern Spain (Desierto de Tabernas, Almería)
    (Murcia: Universidad de Murcia, Servicio de Publicaciones, 2002) Hensen, Isabell; Sin departamento asociado; Facultad de Biología
    Seed predation by ants was studied in the Tabernas Desert (Province of Almería, south-eastern Spain). Eight different species of harvester ants were found collecting seeds in single or foraging trails. Six of them feed mainly or exclusively on seeds. The most important predators are polyphagous Messor ants collecting all available seed types from the soil surface as well as directly from the mother plant. Predation of seeds was confirmed for 41 plant species. Their seed masses vary between 0.08 – 95.9 mg. Resource partitioning according to seed size was not observed, indicating that coexistence of ant species may be facilitated by different foraging strategies. To estimate the influence of seed predation on the vegetation structure, the number of collecting runs per colony per day and composition of food items brought in were determined for Messor bouvieri and M. timidus in a Stipa tenacissima dominated grassland. Collecting-activity correlates strongly with soil temperature. The major part of their diet consists of seeds of Helianthemum almeriense and Launaea lanifera. Both Messor species are very similar with respect to worker size range, size of collected seeds, and foraging strategy, which results in a high degree of dietary overlap
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    Spatiotemporal variations of organochlorine pesticides in an apex predator: Influence of government regulations and farming practices
    (Elsevier, 2019-06-20) Pérez-García, Juan Manuel; León-Ortega, Mario; Enrique Martínez, José; Francisco Calvo, José; Sánchez-Zapata, José Antonio; Botella, Francisco; María-Mojica, Pedro; Martínez-López, Emma; García Fernández, Antonio Juan; Gómez Ramírez, Pilar; Ciencias Sociosanitarias
    Background Intensification of agricultural practices has caused several negative effects to the environment. The use of fertilizers and pesticides may alter geochemical cycles or cause direct wildlife intoxication. Detrimental effects of organochlorine pesticides (OCPs) have forced the authorities to ban or restrict its use. This study evaluates the variation in levels of OCPs in a sentinel species in relation to changes in government regulations and the spatial configuration of agricultural practices around the nests. Methods Between 2003 and 2007, we analysed OCP levels in 256 blood samples of Eurasian Eagle-owl (Bubo bubo) chicks nesting in area of intensive commercial agriculture with historical frequent use of pesticides, in South-eastern Spain. We studied year-to-year variations in OCP concentrations and their relation with land use configuration around raptor nests by Generalized Linear Mixed Models (GLMM). Results OCPs were detected in 100% samples surveyed in 2003 and 2004, while dropped to 27% in 2005, 6.8% in 2006 and 6.3% in 2007, coinciding with the ban of OCPs. The presence of the main OCPs was related to agricultural practices. In particular, endosulfan and lindane were related to irrigated crops and urban areas, while DDT-related compounds and dieldrin were associated with dry land farming. Conclusions OCP concentrations in blood samples of Eurasian Eagle-owls may respond quickly to the implementations of new regulations about the use of agricultural products. This raptor was confirmed as a good sentinel species allowing rapid detection of changes in pesticides use.