26 
THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 124. No. 1. March 2012 
1 ABLE 1. Avian community measures for breeding season birds among burned and unburned plots associaled with ihe 
East Amarillo, Texas Complex wildfires of 2006. 
Short- 
•grass 
Mixed- 
grass 
Burned In = 5) 
Unburned In = 5) 
Bunted In = 5) 
Unbumed <n = 5) 
Species abundance (#/ha) 
2007 
1.806 
1.425 
1.164 
1.702 
2008 
1.714 
1.220 
1.570 
1.446 
Species richness 
2007 
11 
12 
9 
| ] 
2008 
14 
10 
13 
13 
Shannon diversity index (H') 
2007 
1.165 ± 0.119 
1.336 ± 0.092 
1.470 ± 0.075 
1.442 ± 0.067 
2008 
1.669 ± 0.071 
1.582 ± 0.070 
1.605 ± 0.078 
1.804 ± 0.061 
Species evenness (E) 
2007 
2008 
0.589 
0.798 
0.693 
0.835 
0.826 
0.753 
0.782 
0.853 
was the effect of wildfire, not vegetation type, 
and we compared densities only between burned 
and unbumed plots within short- and mixed-grass 
vegetation types, not between the two vegetation 
types. Effect sizes were calculated using Cohen’s 
d (Cohen 1988) with a value ^0.8 considered a 
large effect, and a value <0.2 a small effect. 
We present Cohen’s d supplemental to /-tests to 
facilitate assessments of the effects of year and 
burn treatment. Results may not be statistically 
significant, but the effect size can provide insights 
on biological importance. 
RESULTS 
Short-grass— We detected 13 species on short- 
giass plots in 2007 with II occurring on burned 
and 12 on unbumed plots (Table I). Fourteen 
species were detected on burned plots and 10 on 
unbumed plots in 2008 (Table I). Avian diversity 
was higher (r 239 = 2.06, P = 0.04) on unbumed 
areas in 2007 but was similar across burn 
conditions in 2008 (Table 1). Diversity on burned 
plots was lower (/ 223 = 4.99, P < 0.001) in 2007 
but there was no difference between years on 
unburned plots. 
We performed density analyses for the 
most common species detected: Grasshor 
^parrow (Ammodramus savanna nan). Lark S: 
ow Chandestes grammacus). Horned L 
( (StunZ a 'r tris) ' and Wcs,ern Meadowl 
c n ' rr neHteaa) - ° n average, Grasshop 
Sparrows were present at the highest density of 
species recorded during point-count 2ve 
ranging from 0.32 to 0.44 birds/ha. Differences 
between burn conditions (/* = 0.10. P = 0.46) or 
between years (/ 8 = 0.53, P = 0.30) were not 
significant. Estimated densities of Homed Lark 
were 0.21 /ha on unburned and 0.24/ha on burned 
plots in 2007. Densities on burned plots were not 
different between 2007 and 2008 (0.21 /ha; /* = 
0.20, P — 0.42). Despite a 50% decrease in 
density (0.1 I /ha) among unburned plots in 2008. 
there was no evidence of statistical or biological 
significance to the data (/ 8 = 0.84, P = 0.21. t/ = 
-0.6). However, moderate effect sizes suggest 
densities in 2008 were higher (/« = 0.94, P = 
0.19, (1 = 0.60) on burned plots. Estimated 
densities of Western Meadowlarks in 2007 were 
higher (r 8 = 1.41, P = 0.098. d = 1.0) on 
unburned (0.45/ha) compared to burned plots 
(0.36/ha). The abundance of Western Meadow¬ 
larks decreased to 0.39/ha in 2008 on unbumed 
plots (/ 8 = 0.85, P = 0.21, d — - 1.4), but was not 
significant (Table 2). Lark Sparrows occurred in 
greater numbers on burned plots in both years 
and accounted for >10% of all species detected 
overall (Table 2). Effect sizes suggest Lark 
SpaiTow densities were greater (/ 8 = 1.18, P = 
0.14, d = 0.73) on burned (0.35/ha) compared to 
unbumed (0.14/ha) plots in 2007: differences 
between years within plot types were not 
significant (Table 2). Lark Sparrow densities were 
similar in 2008 on both burned (0.28/ha) and 
unbumed (0.15/ha) plots. Moderate effect sizes 
suggests densities were higher on burned plots in 
2008 (d = 0.57). 
