Figure 1.
Number of breeding pairs (solid squares) and territories (open squares) of bearded vultures in the Spanish Pyrenees from 1985 to 2007.
Figure 2.
Variation in survival rates of adult (>5y and older; open dots) and young birds (4y and younger; solid dots) with time and age using the parameters obtained with the model [φ(1_4+5)+T, pA].
Mean values and 95% lower confidence intervals are shown, as well as the linear negative trends for adults (dashed line) and young (solid line). Survival rates estimated as 1 were actually estimable parameters, i.e. years in which all individuals survived. Note that the two trends were parallel in the logit scale.
Table 1.
Models of survival and resighting probabilities for bearded vultures in the Spanish Pyrenees.
Figure 3.
Response of population growth rate (λ) of Spanish bearded vultures to changes in survival of young and adult birds.
For each combination of two parameters, a stochastic population simulation was run over 50 years. The horizontal plane shows the population stability, i.e. the area above that plane indicates the combination of survival parameters with positive growth. The open dot shows the actual combination of parameters estimated by capture-recapture modelling, while the vertical arrow shows the minimum pre-adult and adult survival to attain a positive population growth rate.
Table 2.
Survival and fertility parameters used in Monte Carlo simulations for estimating extinction risk in prospective models for the bearded vulture in the Spanish Pyrenees depending on the scenario considered.
Figure 4.
Retrospective analysis of the dynamics of the Spanish population of bearded vultures in the Pyrenees during 1985–2007.
Simulations were carried out using estimated values of (a) actual survival rates, i.e. with the effects of poison and AFS; and (b) survival with poison effects but without AFS. Dashed lines show the mean value of stochastic trajectories using Monte Carlo simulations, while open dots are the maximum and minimum values of that run. For comparison, we show the observed number of breeding territories through time (solid lines).
Figure 5.
Stochastic population projections estimated through Monte Carlo simulations (50y of temporal window, 500 runs) for some of the scenarios considered: (a) actual values of adult survival without temporal autocorrelation in poisoning, (b) actual values of adult survival with temporal autocorrelation in poisoning, (c) no impact of poisoning, assuming that young and adult survival were equal, and (d) no impact of poisoning, assuming that survival of young and adults were the same t (see text for details).
Lines are mean values of the stochastic runs for each time step, while dots shows the maximum and minimum values of those runs. Projections were carried out on density of females of any age, which have different scales in each graph.
Figure 6.
Life cycle of the bearded vulture study population with post-breeding census.
The nodes show the different age-classes considered in the models: J for juveniles and Si for survival of each age-class i; F: fecundity (reproductive success); sr: sex ratio (0.5); Pi: breeding probability of each age-class i. The model is only for females.