One of the most striking results of our analysis is the exquisite sensitivity of our Black Harrier populations to adult survival rates. This is consistent with previous studies that showed population of long-lived birds being largely influenced by adult survival (\citealt{Mart_nez_Abra_n_2011,Carrete_2009,Saether2000},  see also \citealt{Schorcht_2009} for bats). On the one hand this means that uncertainty in this life history parameter could potentially impact our conclusions. On the other hand, considering that fertility rates for the Black Harrier are well grounded from all habitats over multiple years \citep{Curtis2004,Garcia_Heras_2017}, there is little room for changing adult survival rates without drifting away from the current expected population trend. One of the least understood parameters in the life history of the Black Harrier is the survival rate of young birds. However, our results suggest that populations are relatively robust to changes in fledgling survival, which reinforces our confidence in our model predictions.