Does expected future habitat condition support proposed population objectives for boreal landbirds in Bird Conservation Region 6 - Boreal Taiga Plains

Background/Question/Methods

Setting and meeting population objectives for priority landbirds should be informed by:  1) the quantity and quality of available habitat, 2) a quantitative relationship between habitat condition and population response, and 3) expected future habitat conditions.  The objective of this study was to demonstrate our approach for “stepping forward” Bird Conservation Region (BCR) scale population objectives for three boreal landbirds within a 6.8 million hectare study area in northeastern Alberta, Canada.  A habitat assessment was conducted to summarize the current availability of forested habitat types within our study area using forest resource inventory data.  Data from 52,552 point counts from 13,342 survey locations within the boreal regions of Alberta was used to model predicted counts of bird abundance within all forested habitat types using local-scale attributes of forest type and age.  Habitat-specific bird density estimates were applied to current and future landscape condition to determine whether proposed BCR numerical population objectives could be achieved over the next 30 years.   

Results/Conclusions

The current forested landscape was dominated by hardwood (19.5%) following by pine (8.0%), mixedwood (6.6%), white spruce (3.1%), and hygric softwood/black spruce (0.94%).  Hardwood, pine and mixedwood forest types were dominated by mature age classes (61-80 years), white spruce forests were dominated by old age classes (101-160 years), and hygric softwood/black spruce forests were dominated by mature and old age classes.  Predicted density estimates were highest in old hardwood and old mixedwood age classes (>121 years) for Black-throated Green Warbler; old hardwood (>141 years), old mixedwood (>121 years), and old white spruce age classes (>121 years) for Western Tanager, and herb and shrub/herb age classes (1-20 years) for White-throated Sparrow.  For all species examined, simulated future population estimates for three alternate scenarios (Business As Usual, Protected Areas, Climate Change) fall short of BCR 6 proposed numerical population objectives calculated for the study area.  Our results suggest that using dynamic land use models to develop hypotheses about expected future habitat conditions can be used to 1) link habitat change to population change estimates, 2) develop population-based habitat targets, and 3) focus strategic conservation actions for multiple landbird species.