Results

The dynamic occupancy model estimates a Black Harrier mean adult survival of \(0.715\pm0.051\), a mean fledgling survival of \(0.502\pm0.072\) and a mean fecundity (with average rainfall for the period) ranging from \(0.564\) to \(0.960\) (mean \(\pm\) standard deviation) (table \ref{tbl:post_param}). These life history parameters translate to a mean population rate of change of \(0.985\pm0.011\) (i.e. approximately 1.5% annual decline). The model also estimates an initial \(0.725\pm0.083\) Black Harriers per pentad on average, which considering that the species as been detected in \(1070\) pentads between 2008-2019, and simulating from the posterior distribution of mean initial abundance (\(\lambda_0\)) we obtain an estimate of \(776\pm92\) Black Harriers in the population of 2008.
We assessed model fit by running posterior predictive simulations of the probability of observing at least one Black Harrier in a pentad and comparing it to the actual data (figure \ref{747849}). Based on this analysis, we conclude that the model captures the general structure in the data but not a pronounced increase in reporting rates in the year 2014.
The elasticity analysis shows that changes in adult survival have a greater impact on population changes (elasticity = \(0.570\pm0.066\)) than fecundity (elasticity = \(0.215\pm0.033\)) or chick survival (elasticity = \(0.215\pm0.033\)) (see figure \ref{642524}).
Our simulations reveal that, given our model, the probability of extinction of the species in under 100 years increases substantially with each individual removed from the population (figure \ref{320177}) . Under average rainfall conditions we expect Black Harrier population to endure another 100 years with no additional mortality. With one additional adult being removed from the population per year, the species could go extinct in under 100 years with probability 0.056. With three adult individuals removed from the population per year, the probability of extinction increases to 0.573. Finally, with five adults removed per year the estimated probability of extinction in 100 years is 0.872.