Nuthatch fecundity improves with mountain pine beetle outbreak

Submitted by avianbiology on 7 April 2014.

Kathy Martin and her lab group have been studying cavity-nesting bird communities in British Columbia since 1995. In 2003, they noticed a steep increase in Red-breasted Nuthatch populations. At the same time, a Mountain Pine Beetle outbreak was sweeping across British Columbia, which they also detected on vegetation surveys. The number of Red-breasted Nuthatch individuals doubled in one year on point counts, which correlated with an increase in mountain pine beetle (Norris and Martin 2010, Oikos). In addition, they found more Red-breasted Nuthatch nests than usual (a four-fold increase relative to early years of the study; Norris and Martin 2012, Ecoscience).  Red-breasted Nuthatches were very motivated to breed during this time, as one pair was found sharing a nest at the same time with a pair of Mountain Chickadees (Robinson et al. 2005, Wilson Bulletin). Mountain pine beetle is a good food source for bark insectivores, such as nuthatches, so the purpose of this study was to determine whether the increase in food availability provided by Mountain Pine Beetle influenced fecundity, in addition to the increase in breeding activity that they had observed. Here they show that indeed fecundity of Red-breasted Nuthatches increased, with the beetle outbreak enabling pairs to lay larger clutches later in the season including some second clutches, and fledging more young per nest.

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