Impacts of supplemental feeding on survival rates of black-capped chickadees

Parus atricapillus with access to supplemental food had higher average monthly survival rates (95 vs. 87%), higher over-winter survival rates (69 vs. 37%), and higher standardized body masses (an additional 0.13 g) than birds on control sites. Differential survival occurred primarily during months with severe weather (>5 d below -18^oC). During these months, high energy demands probably made it difficult for birds without access to supplemental food to obtain sufficient energy from dispersed natural sources. Also, during periods of extreme weather when foraging may be difficult, the extra fat carried by individuals that are supplementally fed may increase the probability of survival. -from Authors