Binmix models fitted to count data of singing male Marsh Tits from Białowieża Forest, eastern Poland, 1987–2019. λ is abundance, and P is detection probability. In the submodel for abundance, λ was modeled as: (.) = constant, year = year dependent, plot = plot dependent, and plot + year = plot and year dependent. The detection probability P was modeled as survey dependent, countersinging dependent, or both. k is the number of parameters, ΔAIC is the difference between the top-supported model and a given model in AIC units, and w_i is the model weight. Models ranked according to AIC. The top-supported model is indicated in bold. Symbol (+) in the last column indicates w_i < 2e-13.