This document discusses factors that influence the microclimate within tree cavities used by nesting birds. It hypothesizes that microclimate is influenced by both external factors like canopy cover and diameter of the tree, and internal factors like wood density and cavity dimensions. The study aims to understand how these factors impact temperature regimes within cavities and influence nesting success. Field data was collected on over 100 cavities measuring external temperature, tree properties, cavity features, and internal temperature. Statistical analyses will evaluate relationships between microclimate temperatures and external and internal cavity characteristics.

2.  Introduction
 Methods
 Literature Cited
 Questions

3.  Roles of Nest Cavities
 Management Implications
 Microclimate Selection
 Importance
 Research Question
 Hypotheses and Predictions

4.  Primary cavity nesters are
keystone species for forest
biodiversity and indicators of
ecosystem health 1, 3, 6, 9, 13, 14
 Cavities provide protection from
predators and external
environment 14, 15
 Cavity availability limits non-
excavating cavity users 3, 14

5.  Cavity nesters form complex webs 2, 9
 Guild management benefits many species 3, 6, 14

6.  Suitable snag retention critical to management 1
 Live-unhealthy and recently dead trees are most
often selected by cavity excavators2
 External decay profile poor indicator of internal
decay 2

7.  Cavity location and
depth influenced by
pockets of decay 2,13, 15
 Snag properties and
surrounding
environment affects
cavity microclimate 1
 Microclimate extremes
influence fitness costs to
nestlings and adults 11

8.  Cavity selection for stable/moderate
thermal regimes correlated with… 10, 11
Tree health 3, 13
Diameter at cavity height 3, 4, 13
Cavity orientation 3, 13
Entrance diameter 10

9.  Optimal environments may…
› Reduce energetic costs to young 7, 11
› Decrease bacterial growth 12
› Increase growth rates of young 5
 Studies have yet to consider wood density and hardness
as influencing microclimate within the cavity
 Microclimate attributed to buffering capacity 4

10.  Microclimate correlated to tree health, diameter at
cavity height, and orientation 14
 Climate change could cause shifts in snag selection
 Microclimate analysis can be used to understand:
› Influence of hardness on thermal regimes
› Aspects of ideal microclimate
› Forest management approaches

11.  How do external and internal
factors influence microclimate
(temperature) created by the
cavity?
› External factors: canopy cover,
external temperature, and
diameter at cavity height
› Internal factors: wood density,
cavity depth (horizontal and
vertical), and entrance diameter

12.  Microclimate will be influenced by canopy
cover, wood density, diameter at cavity
height and entrance diameter.
 Moderate thermal regime as a result of…
› Small entrance diameter
› Increased amount of internal decay
› Increased diameter at cavity height
› Increased canopy cover
***Orientation may be important, however,
influences can be counteracted by canopy
cover

13.  Data Collection
 Study Area
 My Data
 Data Analysis

14.  Previous study by
Teresa Lorenz in 2013:
260 cavities
Tree species
Excavator species
Snag hardness
Cavity height
Orientation
Location
And much more…

15.  Study sites concentrated: 260 110 cavities
› Elevation below 4000 ft
› Cavities between 3 and 25 ft high
› Intact (not depredated)
› Significant tree species
› Significant Study areas
› Localized proximity

16. Figure 1. Four major study areas indicated by the clustered points. Green points indicate cavities in the
Wenas study area, yellow points indicate those of the Nile study area, purple points represent Rattle,
and blue represents Rimrock. These areas occur within or near the Okanogan-Wenatchee National
Forest on the eastern slopes of the Cascade Mountain Range, Washington, USA. These areas were
plotted using Google Earth.
Yakima

17.  Internal
Factors of
Microclimate
Entrance
diameter
Hardness
Cavity
vertical and
horizontal
depth
Temperature
using
iButtons

18.  External Factors of
Microclimate
Temperature with
iButtons outside
Diameter at cavity
height 13
Canopy cover
(modified
hemispherical
approach) 8

19.  Statistical Analysis Software SAS 9.0
 Paired T-Test: temperature inside and outside
cavity
 Paired T-Test: diameter at cavity height and
depth measurements
 Analysis of best fit models (AIC): internal and
external affects on temperature difference

20. 1Aitken, K. E. H., and K. Martin. 2004. Nest cavity availability and selection in aspen-conifer
groves in a grassland landscape. Canadian Journal of Forest Research 34:2099-
2109.
2Blanc, L. A., and K. Martin. 2012. Identifying suitable woodpecker nest trees using decay
selection profiles in trembling aspen (Populus tremuloides). Forest Ecology and
Management 286:192-202.
3Cockle, K. L., K. Martin, and G. Robledo. 2011. Linking fungi, trees, and hole-using birds in
a Neotropical tree-cavity network: Pathways of cavity production and
implications for conservation. Forest Ecology and Management 264:210-219.
4Coombs, A.B., J. Bowman, and C.J. Garroway. 2010. Thermal properties of tree cavities
during winter in a northern hardwood forest. Journal of Wildlife Management
74:1875-1881.
5Dawson, R.D., C.C. Lawrie, and E.L. O’Brien. 2005. The importance of microclimate
variation in determining growth and survival of avian offspring: experimental
evidence from a cavity nesting passerine. Oecologia 144:499-507.
6Drever, M. C., and K. Martin. 2009. Response of woodpeckers to changes in forest health
and harvest: Implications for conservation of avian biodiversity. Forest Ecology
and Management 259:958-966.
7Howe, S., D.L. Kilgore Jr., and C. Colby. 1987. Respiratory gas concentrations and
temperatures within nest cavities of the northern flicker (Colaptes auratus).
Canadian Journal of Zoology 65:1541-1547.
8Jonckheere, I., S. Fleck, K. Nackaerts, B. Muys, P. Coppin, M. Weiss, and F. Baret. 2004.
Review of methods for in situ leaf area index determination: Part I. Theories,
sensors and hemispherical photography. Agricultural and Forest Meteorology
121:19-35.

21. 9Martin, K., and J. M. Eadie. 1999. Nest webs: A community-wide approach to the
management and conservation of cavity-nesting forest birds. Forest Ecology and
Management 115:243-257.
10Rhodes, B., C. O’Donnell, and I. Jamieson. 2009. Microclimate of natural cavity nests
and its implications for a threatened secondary-cavity-nesting passerine of New
Zealand, the south island saddleback. The Condor 11:462-469.
11Robertson, B.A. 2009. Nest-site selection in a postfire landscape: Do parents make
tradeoffs between microclimate and predation risk? The Auk 126:500-510.
12Ruiz-De-Castañeda, R., A.I. Vela, S. González-Braojos, V. Briones, and J. Moreno. 2011.
Drying eggs to inhibit bacteria: Incubation during laying in a cavity nesting
passerine. Behavioural Processes 88:142-148.
13Savignac, C., and C.S. Machtans. 2006. Habitat requirements of the Yellow-bellied
Sapsucker, Sphyrapicus varius, in boreal mixedwood forests of northwestern
Canada. Canadian Journal of Zoology 84:1230-1239.
14Wiebe, K.L. 2001. Microclimate of tree cavity nests: Is it important for reproductive
success in Northern Flickers? The Auk 118:412-421.
15Wesolowski, T. 2011. “Lifespan” of woodpecker-made holes in primeval temperate
forest: A thirty year study. Forest Ecology and Management 262:1846-1852.
16Zahner, V., L. Sikora, and G. Pasinelli. 2012. Heart rot as a key factor for cavity tree
selection in the black woodpecker. Forest Ecology and Management 271:98-
103.

22.  Slide 1: http://yakamafish-nsn.gov/restore/projects/woodpecker-nest-site-
characteristics-managed-ponderosa-pine-stands,
http://www.sierraforestlegacy.org/FC_SierraNevadaWildlifeRisk/Biodiversity%20
Indicators.php
 Slide 2: http://wdfw.wa.gov/living/snags/
 Slide 4: http://www.art.com/products/p357041821-sa-i4007984/gary-meszaros-
female-hooded-merganser-in-its-tree-hole-nest-cavity-lophodytes-cucullatus-
north-america.htm, http://northwestnaturalmoments.blogspot.com/2011/11/red-
squirrel-peeking-out-of-nest-hole.html, http://yakamafish-
nsn.gov/restore/projects/western-bluebird-nest-survival-managed-ponderosa-pine-
forests
 Slide 5: http://www.faculty.biol.vt.edu/walters/lblanc/CurrentResearch.html
 Slide 6: http://en.wikipedia.org/wiki/Selection_cutting,
http://www.nps.gov/fire/wildland-fire/learning-center/fireside-chats/history-
timeline/operational-inventions-and-developments.cfm
 Slide 7: http://www.peeniewallie.com/2008/07/house-wren-1.html
 Slide 8: http://fletcherwildlifegarden.wordpress.com/2013/11/08/early-november-
2013-at-the-garden/black-capped-chickadee-nest-cavity-in-birch-tree/

23.  Slide 9: http://jimmccormac.blogspot.com/2011/11/red-cockaded-
woodpecker.html, http://pictures.n3po.com/Images/Eggs-in-bird-s-nest-in-tree-
cavity.jpg.html
 Slide 11: http://www.faculty.biol.vt.edu/walters/lblanc/CurrentResearch.html
 Slide 10: http://goeddelphotography.com/portfolio/birds/woodpeckers/northern-
flicker-exiting-nest-cavity/
 Slide 14: http://yakamafish-nsn.gov/restore/projects/woodpecker-nest-site-
characteristics-managed-ponderosa-pine-stand,
http://lafeber.com/wildlife/scarlet-macaws-in-la-moskitia-honduras-what-we-
found/
 Slide 15: http://johnsonmatel.com/blog1/2009/02/ponderosa_pines.html
 Slide 16: Google Earth©
 Slide 17: http://www.fws.gov/carolinasandhills/rcw.html,
http://www.embeddeddatasystems.com/DS1921G-F5--Thermochron-iButton-
40C-thru-85C_p_5.html, Figure 6. Outline of vertical depth, horizontal depth
and sill measurements on a hypothetical cavity.
 Slide 18: Figure 7. Set up of internal and external iButtons and solar shield tent
on a tree.
 Slide 24: http://www.cleveland.com/neobirding/index.ssf/2010/03/post_16.html