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THE WILSON JOURNAL OF ORNITHOLOGY . Vol. 123, No. 2. June 2011 
to investigate densities of nesting Black-backed 
Woodpeckers using a 93-ha subset of the 404-ha 
bum during the 2008 breeding season, the second 
opportunity for nesting (second year) after the fire. 
Our objectives in this paper are to report: (1) very 
high nest densities, and (2) a summation of general 
nesting phenology and site characteristics. 
METHODS 
We located three Black-backed Woodpecker 
nests within the burn in 2007 during limited 
surveys immediately following the fire. The 93-ha 
study area was delineated in early 2008 and two 
and three times weekly, 2- to 7-hr surveys were 
made on toot to locate as many Black-backed 
Woodpeckers and nests as possible. We slowly 
searched the study area for nests during each 
survey, bisecting the habitat in a series of 
transects spaced at 20- to 40-m intervals. When 
a Black-backcd Woodpecker was located, we 
attempted to infer from its behavior whether it 
was (1) paired and (2) near an active nest. We 
recorded the following data when nests were 
located: tree species, tree diameter at breast height 
(DBH). nest height, nest orientation, tree status 
(killed by fire, snag, etc.), and latitude and 
longitude. We revisited previously located nests 
during successive surveys recording data on nest 
phenology for: start of nest excavation, first young 
heard, last young in nest, and first date of no nest 
activity. The entire 93-ha study area was not 
completely covered during each day's survey, but 
cumulative visits over the entire area ensured 
systematic sampling. The nature of the habitat 
with relatively small, discrete blocks of burned 
pines with little understory vegetation, set within 
a matrix of burned dear-cuts, made it relatively 
easy to keep track ol our location in relation to 
woodpeckers. The desire to find all Black-backed 
Woodpecker nests in the study area and limited 
hours available prevented following any one pair 
or nest intensively. We conducted surveys from 7 
January 2008 through 7 December 2009 with 40 
surveys totaling 160 hrs concentrated in March 
through July: 199.5 survey hrs were accumulated 
in the total survey period of January-December. A 
period from 28 May through 3 June had no 
surveys at all. 
We used circular statistics (Rao's spacing test, 
U\ mean vector length, r) following Rendell and 
Robertson (1994) for nest tree data to ascertain if 
nest entrance orientation was correlated with 
compass direction. Significance was set at P < 
0.05. Nest locations were also plotted, based on 
Global Positioning System (GPS) locations, to 
calculate accurate densities of nests within the 
study area (of known si/e). We were able to 
calculate the actual density of nesting individuals’ 
ha in the 93-ha study area (and a 19-ha subset of 
the 93-ha study area where nests were densest) 
based on documentation of woodpecker pairs at 
each nest cavity. 
RESULTS 
Twenty active Black-backed Woodpecker nests 
were found in 2008 within the 93-ha study area 
(Fig. 1). Thirty percent of the 20 nests (n =6) 
were confined to a discrete 19-ha subset of the 93- 
ha study area, and another was in a clear-cut just 
outside the 19-ha stand (Fig. 1). One active nest 
was also found during a 1 -hr survey through a 
stand of mature jack pine -1 km outside the bum 
and study area. The overall nest density for the 
entire 93-ha study area was 0.21/ha, while the 19- 
ha stand had a nest density of 0.3I/ha mid also 
included a successful Hairy Woodpecker il’i- 
coides villosus) nest. 
The first date of nest excavation was 24 March 
('fable 1). One nest failed before young were 
heard (4 Jun), two nests failed after young were 
heard (21-26 Jun) and 17 nests advanced to the 
stage of single large young visible in the nest 
entrance (16-26 Jun ). No evidence of nest failure 
was observed at the 17 remaining nests during >he 
next nest survey, and we projected fledge date 
estimates for each of the 17 nests, based on die 
median date between surveys (Table I). The first 
young heard in nests were on 4 June and the last 
young observed in nests were on 29 June. The 
intermittent nature of visits to each nest (not all 
nests were visited each survey day), the non- 
intrusive observation methods, and the 7-dav gup 
in late May and early June limited the exact 
delineation of nesting phenology. 
Nest heights in the 93-ha study area ranged from 
0.71 to 8.32 m with a mean ± SD of 3.18 ~ 2.25 m- 
Nest tree diameter at breast height (DBH) ranged 
from 16.51 to 40.64 cm with a mean ± SD of 23.62 
± 5-82 cm (Table 1). Eighteen of 20 located nests 
(90%) were in jack pines, of which 77*7 were 
killed by the 2008 fire (Table 1). Orientation of 
nest entrances did not vary significantly with 
respect to compass direction, indicating nests were 
randomly distributed within a 360 field (Rao s 
U = 133.85, P > 0.10); mean vector length was 
