Integrated modeling of waterfowl distribution in western Canada using aerial survey and citizen science (eBird) data.

Studying habitat occupancy at the margins of species’ distributions can be helpful in clarifying species’ requirements and planning management measures. Spruce grouse (Canachites canadensis Linnaeus, 1758), a bird species associated with northern short-needle coniferous forests in North America, has its southeastern range limit where coniferous forests are mixed with temperate deciduous forests and agricultural lands. Some isolated populations are found in these habitats. Using a single-season occupancy modelling approach, we investigated habitat use by spruce grouse, accounting for imperfect detection, in the lowlands of the St. Lawrence River in southern Québec, Canada. We conducted call-response spruce over three years at 279 sites (59 sites in 2007, 100 sites in 2008 and 120 sites in 2009). At the site level, the probability of occupancy was 21% (IC: 10.7% - 37.9%) and probability of detection was 54% (IC: 34.7% - 73.0%). Based on the covariates in the models, occurrence increased with higher cover of coniferous trees and low deciduous shrubs, and decreased with higher cover of deciduous trees. Finally, detection probability was highest at the beginning of the survey (50% in late April) and was influenced by year.

Sandhill cranes (Antigone canadensis) were broadly extirpated from much of their historical range in North America at the beginning of the twentieth century. Various conservationrelated legislation, such as the United States Migratory Bird Treaty Act, have assisted with population recovery. The eastern population of sandhill cranes has been growing rapidly since the 1980s and is thought to have expanded its geographic range to Quebec, Canada. Understanding the colonization and habitat use by the species in previously unoccupied breeding areas is necessary to develop and apply management measures. Using a dynamic occupancy modeling approach, we investigated the recent colonization and extirpation patterns of sandhill cranes in Quebec from 2004-2019. We combined data from 3 data sets (helicopter surveys, breeding bird atlas surveys, and eBird) to increase the spatial coverage and the number of species occurrence records while accounting for imperfect detection probability. Detection probability was highest for the helicopter survey (0.70), whereas the 2 other data sets had relatively low detection levels (0.10-0.26). Based on a simulation study, we found that excluding the eBird data from the analysis produced more biased estimates than excluding the atlas and helicopter survey data sets. Throughout the study, sandhill cranes seemed to have completed their colonization of western Quebec and only recently started to nest in eastern areas. Initial occupancy increased with wetland cover and colonization probability increased weakly with the cover of agricultural areas, suggesting that in our study area sandhill cranes rely essentially on natural wetlands during the breeding season.