Microclimate of Tree Cavity Nests: Is it Important for Reproductive Success in Northern Flickers?

Abstract

I measured structural characteristics of 160 Northern Flicker (Colaptes auratus) nests at Riske Creek, British Columbia, and placed electronic data-loggers in a subsample of 86 nests to record internal temperatures after the flickers completed nesting. Using multiple regression, I found that the best predictors of a variety of nest-cavity temperature variables were tree health, diameter of the tree at cavity height, and orientation of the cavity. Small and dead trees showed the most extreme (maximum and minimum) temperatures during the day, but, on average, were the coldest nests from the perspective of incubation. South-facing cavities reached the highest temperatures during the day, and the orientation of natural cavities was also biased towards the south. I predicted that cold nests would be energetically expensive for adults and nestlings, and found that clutch size was positively correlated with mean cavity temperature. However, there did not appear to be any relationship among nest temperature and hatching or fledging success.

Microclimate of Tree Cavities Used by Great Tits (Parus Major) in a Primeval Forest

“…Martin and Ghalambor (1999) found that daily temperature amplitude in cavities of North American Pygmy Nuthatch (Sitta pygmaea) located in dead substrates (McEllin, 1979;Hay and Güntert, 1983), amounted to circa 10°C. Similar daily amplitudes were recorded by Wiebe (2001) in excavated mainly dead wood cavities used previously by Northern Flicker (Colaptes auratus). These results suggest that cavities in living wood would provide better buffered thermal conditions than the cavities in dead substrates.…”

“…An identical pattern was found in all studies done during the breeding season (papers referred to above, and Stains, 1961;Martin and Ghalambor, 1999;Wiebe, 2001), as well as in studies on roosting cavities carried out during the winter (Paclík and Weidinger, 2007;Coombs et al, 2010). Thus, tree cavities appear to dampen the daily temperature fluctuations and provide a much more stable thermal environment than the world outside.…”

“…Data on microclimate in tree cavities occupied by breeding birds are rare Hooge et al, 1999;Martin and Ghalambor, 1999;Wiebe, 2001;Ar et al, 2004;Rhodes et al, 2009, Mersten-Katz et al, 2012. We presumed that different types of cavities would provide contrasting environments, but there are hardly any data to check this.…”

“…We presumed that different types of cavities would provide contrasting environments, but there are hardly any data to check this. Available data indicate, though, that air temperatures in cavities may depend on their locality and dimensions (Hooge et al, 1999;Wiebe, 2001;Sedgeley, 2001;Packlík and Weidinger, 2007;Rhodes et al, 2009;Coombs et al, 2010). Thus, by selecting cavities with appropriate attributes, the birds would able to adjust microclimatic conditions in cavities to their requirements, at least to some extent.…”

The Effects of Nestbox Thermal Environment on Fledging Success and Haematocrit in Tree Swallows

“…In Northern Flickers (Colaptes auratus) breeding in natural tree cavities in British Columbia, nest temperature had no effect on reproductive success (Wiebe, 2001). Although, warmer internal temperatures in artificial cavities used by American Kestrels (Falco sparverius) led to increased hatching success, the overall effect on seasonal fitness is unknown (Butler et al, 2009).…”