International Journal of Biometeorology

, Volume 57, Issue 3, pp 437–450 | Cite as

Tree structure and cavity microclimate: implications for bats and birds

  • Matthew J. ClementEmail author
  • Steven B. Castleberry
Original Paper


It is widely assumed that tree cavity structure and microclimate affect cavity selection and use in cavity-dwelling bats and birds. Despite the interest in tree structure and microclimate, the relationship between the two has rarely been quantified. Currently available data often comes from artificial structures that may not accurately represent conditions in natural cavities. We collected data on tree cavity structure and microclimate from 45 trees in five cypress-gum swamps in the Coastal Plain of Georgia in the United States in 2008. We used hierarchical linear models to predict cavity microclimate from tree structure and ambient temperature and humidity, and used Aikaike’s information criterion to select the most parsimonious models. We found large differences in microclimate among trees, but tree structure variables explained <28 % of the variation, while ambient conditions explained >80 % of variation common to all trees. We argue that the determinants of microclimate are complex and multidimensional, and therefore cavity microclimate cannot be deduced easily from simple tree structures. Furthermore, we found that daily fluctuations in ambient conditions strongly affect microclimate, indicating that greater weather fluctuations will cause greater differences among tree cavities.


Cypress-gum swamp Hierarchical linear model Humidity Microclimate Temperature Tree cavity 



We thank C. Carpenter for field assistance and Bat Conservation International for loaning data loggers. The Georgia Department of Natural Resources provided access and housing at all study sites. Funding was provided by the Georgia Department of Natural Resources Wildlife Resources Division and the Daniel B. Warnell School of Forestry and Natural Resources at the University of Georgia.


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Copyright information

© ISB 2012

Authors and Affiliations

  1. 1.D.B. Warnell School of Forestry and Natural ResourcesUniversity of GeorgiaAthensUSA
  2. 2.Western Ecosystems TechnologyBloomingtonUSA

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