Search results for " population trend"
showing 4 items of 4 documents
Status of Egyptian vulture (Neophron percnopterus) in Sicily.
2009
La población del buitre Neophron percnopterus en Sicilia se encuentra restringida a los sectores central y oeste de la isla. La población alcanzó cerca de 30 parejas durante el periodo entre 1970 y 1980, auque durante nuestro periodo de estudio (1990–2007), la población tuvo un tamaño promedio de sólo 7 ± 2 parejas más 2 ± 1 individuos no emparejados, con fluctuaciones considerables en los números. Las tasas reproductivas durante nuestro periodo de estudio (juvenil por pareja reproductiva y juvenil por nido exitoso) fueron típicas para una población europea, aunque la tasa de éxito de los nidos disminuyó y el abandono de nidos durante el período 2000–2007 fue el doble del registrado durante…
Climate and land-use changes as determinants of lesser kestrel Falco naumanni abundance in Mediterranean cereal steppes (Sicily)
2010
Monitoring of lesser kestrels Falco naumanni is necessary to promote conservation of this vulnerable species. To this end, 35 colonies of this species located in the NNW and SE of Sicily were monitored from 2003 to 2009. Counts of the active colonies and resident pairs were modelled by loglinear Poisson regressions to assess population trends over the study period. Afterwards, a GLM with an analysis of covariance design and a backward removal stepwise regression was performed to relate the observed trend to local- or global-scale climatic variation and to local land-use changes. Colony counts provided a better fit to the loglinear models than pair counts. Loglinear models separated the incr…
Different trends of neighboring populations of Lesser Kestrel: Effects of climate and other environmental conditions
2019
The sensitivity of population trends to the climate and environment is generally considered a species-specific trait. However, evidence that populations may show different responses to the climate and environmental conditions is growing. Whether this differential sensitivity may arise even among neighboring populations remains elusive. We compared the trends of two neighboring populations of the Lesser Kestrel Falco naumanni, using data from a 12-year survey of 158 colonies in Sicily, Italy; the two populations inhabiting a lowland and an highland area, respectively. Population trends were modeled through the TRIM algorithms implemented in R (package rtrim). A reversed U-shaped population t…
Strategie di controllo di Bactrocera oleae (Rossi) con metodi alternativi agli interventi convenzionali in oliveti biologici della Sicilia occidentale
2011
This work reports studies on the population dynamics and safe control strategies of Bactrocera oleae in four unsprayed olive groves of western Sicily from 2007 to 2010. The main management tools for B. oleae evaluated were the“Attract and Kill” lures (Ecotrap Vioryl), the use of sardines (traditional practice) and Nu-lure (innovative) and the spinosad (innovative) which is a selective insect control product produced by the fermentation of a naturally occurring soil bacterium, Saccharopolyspora spinosa. Flies trend were carried out by pheromone traps and the level of infestation counting the number of fruits with pest eggs, larvae and pupae and hole hatching. Results showed that in all olive…