Grassland bird community response to large wildfires.
Abstract: We studied breeding season communities of grassland birds on short-grass and mixed-grass prairie sites during the second and third breeding seasons following two large wildfires in March 2006 in the Texas panhandle, USA. There was an apparent temporary shift in avian community composition following the fires due to species-specific shifts associated with life-history traits and vegetation preferences. Species that prefer sparse vegetation and bare ground on short-grass sites, such as Horned Lark (Eremophila alpestris), benefited from wildfires, while others, such as Western Meadowlark (Sturnella neglecta), that prefer more dense vegetation, were negatively impacted. Mixed-grass sites had species-specific shifts in 2007, two breeding seasons after the fires; grassland bird communities on burned plots were similar by 2008 to those on unburned plots. Avian communities appeared to return to pre-burn levels within 3 years following wildfires. Many of the responses in our study of wildfire were similar to those reported following prescribed fires elsewhere. Prescribed fires appear to have similar effects on the avian community despite differences in intensity and environmental conditions during wildfires.
Article Type: Report
Subject: Wildfires (Environmental aspects)
Grasslands (Environmental aspects)
Birds (Environmental aspects)
Authors: Roberts, Anthony J.
Boal, Clint W.
Wester, David B.
Rideout-Hanzak, Sandra
Whitlaw, Heather A.
Pub Date: 03/01/2012
Publication: Name: The Wilson Journal of Ornithology Publisher: Wilson Ornithological Society Audience: Academic Format: Magazine/Journal Subject: Biological sciences Copyright: COPYRIGHT 2012 Wilson Ornithological Society ISSN: 1559-4491
Issue: Date: March, 2012 Source Volume: 124 Source Issue: 1
Geographic: Geographic Scope: United States Geographic Code: 1USA United States
Accession Number: 285207238
Full Text: Fire is a driving ecological process of healthy grassland ecosystems. Following a history of fire suppression, the application of prescribed fire has become a contemporary method to manage grasslands. However, it is unclear how well prescribed fires can replicate the ecological values of natural fires. For example, studies of grassland bird response to fire have focused on effects of prescribed fire (e.g., Huber and Steuter 1984, Madden et al. 1999, Kirkpatrick et al. 2002, Grant et al. 2010); no published studies have examined the impact of wildfires on avian communities in Great Plains grasslands. Prescribed fires are generally conducted in low wind and high humidity conditions that promote controlled burning. Wildfires may be more intense than prescribed fires and cover larger spatial scales. Litter is decreased, woody plants are often killed or burned completely, and live plants are killed at high rates (Rideout-Hanzak et al. 2011). This removes structure from the landscape, affecting the poorly understood avian community in unknown ways (Smith 2000). There is potential for increased frequency and size of wildfires in the coming decades due to warmer temperatures and less precipitation, as predicted by current climate change models (North American Bird Initiative 2010). Numerous bird species of concern occur in the short-grass prairies of the southern Great Plains, an assemblage of some of the least ecologically understood of all grassland birds (Askins et al. 2007). The effects of wildfires on these and other species are unknown.

Two large wildfires ignited east of Amarillo in the Texas panhandle, USA on 12 March 2006. Together the fires burned 360,000 ha of predominantly private lands in what is known as the East Amarillo Complex (EAC) wildfires (Zane et al. 2006). Widespread vegetation loss on the mixed-grass and short-grass ecosystems had potentially large negative impacts on numerous species of grassland obligate songbirds that breed in the Southern High Plains. The EAC presented a rare opportunity to examine the effects of large-scale wildfires on grassland bird populations. The objectives of our study were to: (1) examine the changes in avian species densities after a wildfire, and (2) how avian community composition adjusts in the years following the wildfires.

METHODS

This study was conducted on private ranches in Roberts, Gray, and Donley counties in the Texas panhandle. This area is in the Rolling Plains ecoregion of Texas, a transition zone between short-grass and mixed-grass prairie types in the Southern High Plains. The landscape is characterized by rolling hills leading to flat plains interspersed with ephemeral wetland depressions known as playas (Williams and Welker 1966). Elevation ranges from 420 to >600 m. The climate is characterized by hot summers and cold to mild winters, but temperatures fluctuate extensively within seasons (Williams and Welker 1966). The mean summer temperature (May-Jul) for 2007 and 2008 was 22.3[degrees]C (U.S. Department of Commerce 2009). Historically the Texas panhandle received an average of 53 cm of precipitation a year (Williams and Welker 1966); the study area received ~61 cm of precipitation annually during the study period.

Study Plot Selection.--We selected 20 survey plots for study based on access to private property, burn history, and vegetation community type of either short-grass or mixed-grass prairie (centered at 14 S 342427 E, 3928890 N). The latter distinction was based on soil type and dominant vegetation. Burn type, either burned or unburned area, was established by talking with landowners and local officials, and visual examination of any woody vegetation in the area such as prickly pear cactus (Opuntia spp.), catclaw mimosa (Mimosa aculeaticarpa), or sand sagebrush (Artemisia filifolia). We were unable to initiate this study and select sites until the fall following the EAC fires and were unable to examine avian communities during the breeding season directly after the fires occurred. The 20 plots were equally distributed among areas identified as short-grass burned, short-grass unburned, mixed-grass burned, and mixed-grass unburned. Individual plots were at least 1 km apart and 0.5 km from a known fire boundary, roads, or other vegetation or topographic changes. We analyzed each vegetation type separately to examine within-type differences among five replicates each of burned and unburned plots. All study sites were on private property and we were unable to alter grazing regimes; sites ranged from no grazing to moderate stocking levels.

Breeding Season Surveys.--We used fixedradius point counts to survey avian populations within the 20 plots, May-June, 2007 and 2008. We conducted surveys using a three by three grid of nine 75-m radius point counts for a total survey area of ~16 ha at each plot. We used three observers throughout the study, all of whom had either prior experience with grassland bird identification or were trained prior to surveys.

Point-count centers were placed 200 m apart to minimize risk of recounting individuals (Ralph et al. 1993). We conducted surveys between 0.5 hrs before and 3 hrs after sunrise. We did not survey points during inclement weather such as rain, or in winds >16 km/hr (Ralph et al. 1993). Observers recorded all birds flushed within 75 m of the point when walking to a point. All birds heard or seen in the 75-m radii within a 7-min window were recorded and the distance from the observer was estimated (Reynolds et al. 1980). Birds seen while walking between points and birds that flew overhead but not using the area within the radii were not recorded.

Data Analysis.--We used both the May and June surveys to create a measure of average abundance and species diversity measures over the breeding season. Average abundance was calculated by averaging the count of each species between the two survey periods. We calculated species diversity using the Shannon diversity index (H'; Shannon and Weaver 1963). Taylor (1978) suggested that diversities calculated over a variety of samples are normally distributed, but we used the more robust t-test suggested by Hutcheson (1970) to compare H' across burn conditions. Hutcheson's t-test uses the number of individuals to calculate degrees of freedom, often resulting in large numbers. We derived evenness (E) from H' using the ratio of observed to maximum diversity as described by Magurran (1988).

We only used singing males from June surveys to calculate density estimates. We were only interested in the number of breeding territories supported in each habitat type in contrast to richness and diversity measures. June surveys were during the height of the breeding season when territories were established, and indicative of the density of breeding pairs. We used actual counts of singing males rather than estimates of density derived using detection probabilities. Species-specific estimates of detection probabilities introduce additional sources of variability (Johnson 2008), and we believed detection probability in a grassland landscape is close to one and similar across burn conditions, especially given our survey was based on territorial males that are announcing their presence (Thompson et al. 2009). Density estimates are an average of the five plots in each treatment. We compared densities among years and burn treatments using a t-test with an alpha level of 0.05. Our interest was the effect of wildfire, not vegetation type, and we compared densities only between burned and unburned 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 [greater than or equal to] 0.8 considered a large effect, and a value [less than or equal to] 0.2 a small effect. We present Cohen's d supplemental to t-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 shortgrass plots in 2007 with 11 occurring on burned and 12 on unburned plots (Table 1). Fourteen species were detected on burned plots and 10 on unburned plots in 2008 (Table 1). Avian diversity was higher ([t.sub.239] = 2.06, P = 0.04) on unburned areas in 2007 but was similar across burn conditions in 2008 (Table 1). Diversity on burned plots was lower ([t.sub.223] = 4.99, P < 0.001) in 2007 but there was no difference between years on unburned plots.

We performed density analyses for the four most common species detected: Grasshopper Sparrow (Ammodramus savannarum), Lark Sparrow (Chondestes grammacus), Horned Lark (Eremophila alpestris), and Western Meadowlark (Sturnella neglecta). On average, Grasshopper Sparrows were present at the highest density of all species recorded during point-count surveys, ranging from 0.32 to 0.44 birds/ha. Differences between burn conditions ([t.sub.8] = 0.10, P = 0.46) or between years ([t.sub.8] = 0.53, P = 0.30) were not significant. Estimated densities of Horned 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; [t.sub.8] = 0.20, P = 0.42). Despite a 50% decrease in density (0.11/ha) among unburned plots in 2008, there was no evidence of statistical or biological significance to the data ([t.sub.8] = 0.84, P = 0.21, d = -0.6). However, moderate effect sizes suggest densities in 2008 were higher ([t.sub.8] = 0.94, P = 0.19, d = 0.60) on burned plots. Estimated densities of Western Meadowlarks in 2007 were higher ([t.sub.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 Meadowlarks decreased to 0.39/ha in 2008 on unburned plots ([t.sub.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 Sparrow densities were greater ([t.sub.8] = 1.18, P = 0.14, d = 0.73) on burned (0.35/ha) compared to unburned (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 unburned (0.15/ha) plots. Moderate effect sizes suggests densities were higher on burned plots in 2008 (d = 0.57).

Mixed-grass.--We observed 12 species on mixed-grass plots in 2007 during the breeding season with nine detected on burned and 11 on unburned plots (Table 1). We detected 17 species on mixed-grass plots in 2008. Barn Swallow (Hirundo rustica), Eastern Kingbird (Tyrannus tyrannus), Killdeer (Charadrius vociferous), and Lesser Prairie-Chicken (Tympanuchus pallidicinctus) were all observed in low numbers on burned plots, but were not detected on unburned plots (Table 3). There was no difference in diversity between burned and unburned plots in 2007. However, diversity on unburned mixed-grass plots in 2008 increased ([t.sub.268] = 3.45, P < 0.001) from that in 2007 and was higher ([t.sub.235] = 2.59, P = 0.01) among burned plots (Table 1). No change was detected in diversity between years on burned plots.

We analyzed Western Meadowlark, Cassin's Sparrow (Peucaea cassinii), Lark Sparrow, and Grasshopper Sparrow densities on mixed-grass plots. Western Meadowlark densities ranged from 0.31 to 0.45 birds/ha; no differences were detected between burn conditions ([t.sub.8] = 0.39, P = 0.35) or years ([t.sub.8] = 0.17, P = 0.43). Estimated densities of Cassin's Sparrows in 2007 were 0.36/ha on unburned compared to 0.29/ha on burned plots ([t.sub.8] = 0.35, P = 0.36, d = 0.3). Densities did not change significantly on burned plots ([t.sub.8] = 0.07, P = 0.47, d = 0.1) or unburned plots ([t.sub.8] = 0.39, P = 0.35, d = -0.3); Cassin's Sparrows occurred at identical abundance by 2008 on both plot types (0.30/ha). Grasshopper Sparrows occurred at significantly higher ([t.sub.8] = 2.2, P = 0.031, d = 1.5) densities on unburned (0.45/ha) than burned plots (0.12/ha) in 2007. Densities numerically decreased ([t.sub.8] = 1.26, P = 0.12, d = -0.9) in 2008 on unburned plots (0.35/ha) and effect size suggest densities increased ([t.sub.8] = 1.17, P = 0.13, d = 0.8) on burned plots (0.32/ha). Lark Sparrow densities were nearly identical on burned (0.23/ ha) and unburned (0.24/ha) plots in 2007. The following year densities on both burn conditions were 0.15/ha; although the numerical decreases were not significant, it appears there was a noticeable effect of year on both burned ([t.sub.8] = 0.83, P = 0.22, d = 0.53) or unburned ([t.sub.8] = 0.85, P = 0.21, d = 0.55) plots.

DISCUSSION

Grasshopper Sparrows were the most abundant species among short-grass plots, and were present in consistent numbers regardless of year or burn condition. This species was significantly more abundant on unburned plots after a wildfire in Montana shrubsteppe (Bock and Bock 1987), suggesting preference for denser vegetation in wildfire in Arizona (Bock and Bock 1992). High effect sizes indicate the higher densities of Western Meadowlarks on burned plots in 2007 may have been biologically relevant, but were not statistically significant in our study. The above-ground plant biomass among burned and unburned plots was similar by 2008 (Rideout-Hanzak et al. 2011), likely providing similar nesting sites and foraging opportunities across burn conditions. Horned Larks prefer areas with a high percentage of bare ground across their range (Beason 1995). Consistent with this general habitat association, Horned Larks decreased in density as burned areas were revegetated and more litter formed.

The composition of avian communities differed on mixed-grass plots in 2007 despite similar diversity and evenness measures across burn conditions. Abundances of Cassin's and Grasshopper sparrows were higher on unburned than burned plots in mixed-grass areas. However, densities of these species on burned plots were similar to unburned plots by 2008. Lark Sparrows on both short- and mixed-grass plots decreased on burned areas from 2007 to 2008. Long-term Lark Sparrow abundance decreased along with the decrease in woody vegetation after a fire in sagebrush (Artemisia spp.) grasslands in Washington State (Earnst et al. 2009). This suggests the avian community may have returned to densities similar to unburned areas by the third breeding season after the wildfires. A homogeneous landscape with plant biomass and structure similar to unburned areas 3 years after the wildfires (Rideout-Hanzak et al. 2011) may have promoted similar avian communities across the landscape.

Historically, fire was a major ecological factor in both short- and mixed-grass ecosystems until intense livestock grazing and fire suppression altered vegetation and fuels so fires could not burn with historic frequency or intensity (Wright and Bailey 1982). Some areas of the Great Plains have seen fire return to the landscape in the form of prescribed fire. The EAC wildfires occurred during high winds and low humidity, different conditions than proscribed for prescribed fires. Prescribed fires appear to have similar influences on the avian community as the EAC wildfires despite differences in intensity and environmental conditions during the wildfire.

Many of the responses measured in our study of wildfire were similar to those observed following prescribed fires. Wintering Cassin's Sparrows in Arizona responded negatively to burning after a prescribed fire, but Grasshopper Sparrows showed no response (Gordon 2000). Abundance of Grasshopper and Cassin's sparrows increased after a prescribed fire in Texas mesquite (Prosopis spp.) savanna (Lee 2006). Prescribed fire in Noah Dakota mixed-grass prairie decreased populations of most species during the breeding season following the fires (Grant et al. 2010); however, 3 years after the prescribed fires, avian populations had increased and stabilized, recovering in a similar time span as in our study. Many species, including Grasshopper Sparrows and Western Meadowlarks, were positively correlated with use of prescribed fire in mixed-grass prairies (Madden et al. 1999). Western Meadowlarks in prairie Canada declined in abundance during the breeding season following prescribed fire, but had comparable densities on burned and unburned areas 3 years post-fire (Pylypec 1991).

We found an apparent temporary shift in avian community composition following wildfires due to species-specific shifts associated with life-history traits and vegetation preferences. The avian community appeared to be similar to that on unburned plots of similar grass types 3 years following the wildfires. This was consistent with vegetation recovery (Rideout-Hanzak et al. 2011). A homogeneous landscape in grasslands decreases the diversity of grassland birds (Fuhlendorf et al. 2006) and the grassland bird community reaches peak densities with increased periodic disturbance in short-grass and mixed-grass landscapes. Two of the most common species detected on short-grass plots, Grasshopper Sparrow and Horned Lark, are among 20 common North American birds experiencing the steepest population declines (Butcher and Niven 2007). The area burned by the EAC wildfires may not only provide important habitat for continued persistence of species of concern, but fire may be an integral component of habitat health for the avian community.

Persistence of a diverse and abundant avian community is dependent on periodic disturbances such as wildfire or prescribed fire, grazing, and drought to provide patches of habitat in varying stages of growth after disturbance (Fuhlendorf and Engel 2001). Prescribed fire has been used to mimic wildfire effects and reduce wildfire potential (Pattison 1998). Rideout-Hanzak et al. (2011) suggest the EAC fires may not have created drastically different conditions than a prescribed fire in this ecosystem; this was corroborated by the avian community response. The wildfires may have been ecologically beneficial in providing similar services to plants and soil as historic fire regimes on the Southern High Plains. The combination of varying grazing regimes and periodic prescribed fire in the Texas panhandle would facilitate development of a mosaic of grassland patches in varying stages of recovery from disturbance, and offer a wide variety of niches for grassland birds.

ACKNOWLEDGMENTS

We thank the many landowners who allowed access to their properties for this research. This study was funded by the Natural Resources Conservation Service, Texas Parks and Wildlife Department, and Texas Tech University.

Received 8 November 2010. Accepted 10 October 2011.

LITERATURE CITED

ASKINS, R. A., F. CHAVEZ-RAM1REZ, B. C. DALE, C. A. HASS, J. R. HERKERT, F. L. KNOPF, AND P. D. VICKERY. 2007. Conservation of grassland birds in North America: understanding ecological processes in different regions. Ornithological Monographs 64:1-46.

BEASON, R. C. 1995. Horned Lark (Eremophila alpestris). The birds of North America. Number 195.

BOCK, C. E. AND J. H. BOCK. 1987. Avian habitat occupancy following fire in a Montana shrubsteppe. Prairie Naturalist 19:153-158.

BOCK, C. E. AND J. H. BOCK. 1992. Response of birds to wildfire in native versus exotic Arizona grassland. Southwestern Naturalist 37:73-81.

BUTCHER, G. AND D. K. NIVEN. 2007. Combining data from the Christmas Bird Count and the Breeding Bird Survey to determine the continental status and trends of North American birds. National Audubon Society, New York, USA.

COHEN, J. 1988. Statistical power analysis for the behavioral sciences. Lawrence Earlbaum Associates, Hillsdale, New Jersey, USA.

EARNST, S. L., H. L. NEWSOME, W. L. LAFRAMBOISE, AND N. LAFRAMBO1SE. 2009. Avian response to wildfire in interior Columbia Basin shrubsteppe. Condor 111:370-376.

FUHLENDORF, S. D. AND D. M. ENGLE. 2001. Restoring heterogeneity on rangelands: ecosystem management based on evolutionary grazing patterns. BioScience 51:625-632.

FUHLENDORF, S. D, W. C. HARRELL, D. M. ENGLE, R. G. HAMILTON, C. A. DAVIS, AND D. M. LESLIE JR. 2006. Should heterogeneity be the basis for conservation? Grassland bird response to fire and grazing. Ecological Applications 16:1706-1716.

GRANT, T. A., E. M. MADDEN, T. L. SHAFFER, AND J. S. DOCKENS. 2010. Effects of prescribed fire on vegetation and passerine birds in northern mixed-grass prairie. Journal of Wildlife Management 74:1841-1851.

GORDON, C. E. 2000. Fire and cattle grazing on wintering sparrows in Arizona grasslands. Journal of Range Management 53:384-389.

HUBER, G. E. AND A. A. STEUTER. 1984. Vegetation profile and grassland bird response to spring burning. Prairie Naturalist 16:55-61.

HUTCHESON, K. 1970. A test for comparing diversities based on the Shannon formula. Journal of Theoretical Biology 29:151-154.

JOHNSON, D. H. 2008. In defense of indices: the case of bird surveys. Journal of Wildlife Management 72: 857-868.

KIRKPATRICK, C., S. DESTEFANO, R. W. MANNAN, AND J. LLOYD. 2002. Trends in abundance of grassland birds following a spring prescribed burn in southern Arizona. Southwestern Naturalist 47: 282-292.

LEE, S. L. 2006. Post-fire successional effect on breeding grassland birds in mesquite savanna habitats of the Texas rolling plains. Thesis. Texas A&M University, College Station, USA.

MADDEN, E. M., A. J. HANSEN, AND R. K. MURPHY. 1999. Influence of prescribed fire history on habitat and abundance of passerine birds in northern mixed-grass prairie. Canadian Field-Naturalist 113:627-640.

MAGURRAN, A. E. 1988. Ecological diversity and its measurement. Princeton University Press, Princeton, New Jersey, USA.

NORTH AMERICAN BIRD CONSERVATION INITIATIVE. 2010. The state of the birds 2010 report on climate change, United States of America. U.S. Department of the Interior, District of Columbia, Washington, D. C., USA.

PATTISON, M. 1998. Fighting fire with fire: a policy to improve resource management and reduce risk. Renewable Resources Journal 16:13-17.

PYLYPEC, B. 1991. Impacts of fire on bird populations in a fescue prairie. Canadian Field-Naturalist 105:346-349.

RALPH, C. J., J. R. SAUER, AND S. DROEGE. 1993. Monitoring bird populations by point counts. USDA, Forest Service, General Technical Report PSW-GTR149. Albany, California, USA

REYNOLDS, R. T., J. M. SCOTT, AND R. A. NUSSBAUM. 1980. A variable circular-plot method for estimating bird numbers. Condor 82:309-313.

RIDEOUT-HANZAK, S., D. B. WESTER, C. M. BRITTON, AND H. WHITLAW. 2011. Biomass not linked to perennial grass mortality following severe wildfire in the Southern High Plains. Rangeland Ecology and Management 64:47-55.

SHANNON, C. E. AND W. WEAVER. 1963. The mathematical theory of communication. University of Illinois Press, Urbana, USA.

SMITH, J. K. (Editor). 2000. Wildland fire in ecosystems: effects of fire on fauna. USDA, Forest Service, General Technical Report RMRS-GTR-42. Rocky Mountain Research Station, Ogden, Utah, USA.

TAYLOR, L. R. 1978. Bates, Williams, Hutchinson-a variety of diversities. In Diversity of insect faunas: 9th Symposium of the Royal Entomological Society (L. A. Mound and N. Warloff, Editors). Blackwell Publishing, Oxford, United Kingdom.

THOMPSON, T. R., C. W. BOAL, AND D. LUCIA. 2009. Grassland bird associations with introduced and native grass Conservation Reserve Program fields in the Southern High Plains. Western North American Naturalist 69:481-490

U.S. DEPARTMENT OF COMMERCE. 2009. National Oceanic and Atmospheric Administration, Silver Spring, Maryland, USA. http://www7.ncdc.noaa.govllPS/cd/cd.html

WILLIAMS, J. C. AND A. J. WELKER. 1966. Soil survey: Gray County, Texas. USDA, Soil Conservation Service, Washington, D.C., USA.

WRIGHT, H. A. AND A. W. BAILEY. 1982. Fire ecology, United States and southern Canada. John Wiley and Sons, New York, USA.

ZANE, D., J. HENRY, C. LINDLEY, P. W. PENDERGRASS, D. GALLOWAY, T. SPENCER, AND M. STANFORD. 2006. Surveillance of mortality during the Texas panhandle wildfires (March 2006). Final Report to Wildland Fire Lessons Learned Center, Tucson, Arizona, USA. www.wildfirelessons.net

ANTHONY J. ROBERTS, (1,6,7) CLINT W. BOAL, (2) DAVID B. WESTER, (3,4) SANDRA RIDEOUT-HANZAK, (3) AND HEATHER A. WHITLAW (5)

(1) Department of Natural Resources Management, Texas Tech University, Lubbock, TX 79409, USA.

(2) U.S. Geological Survey, Texas Cooperative Fish and Wildlife Research Unit, Texas Tech University, Lubbock, TX 79409, USA.

(3) Department of Animal, Rangeland, and Wildlife Sciences, Texas A&M University-Kingsville, Kingsville, TX 78363, USA.

(4) Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, Kingsville, TX 78363, USA.

(5) U.S. Fish and Wildlife Service, West Texas Sub-Office, Texas Tech University, Lubbock, TX 79409, USA.

(6) Current address: Wildland Resources Department, 5230 Old Main Hill, Logan, UT 84322, USA.

(7) Corresponding author; e-mail: tony.roberts@aggiemail.usu.edu
TABLE 1. Avian community measures for breeding season birds among
burned and unburned plots associated with the East Amarillo, Texas
Complex wildfires of 2006.

                           Short-grass

             Burned (n = 5)         Unburned (n = 5)

Species
abundance
(#/ha)

2007         1.806                  1.425
2008         1.714                  1.220

Species
richness

2007         11                     12
2008         14                     10

Shannon
diversity
index (H')

2007         1.165 [+ or -] 0.119   1.336 [+ or -] 0.092
2008         1.669 [+ or -] 0.071   1.582 [+ or -] 0.070

Species
evenness
(E)

2007         0.589                  0.693
2008         0.798                  0.835

                           Mixed-grass

             Burned (n = 5)         Unburned (n = 5)

Species
abundance
(#/ha)

2007         1.164                  1.702
2008         1.570                  1.446

Species
richness

2007         9                      11
2008         13                     13

Shannon
diversity
index (H')

2007         1.470 [+ or -] 0.075   1.442 [+ or -] 0.067
2008         1.605 [+ or -] 0.078   1.804 [+ or -] 0.061

Species
evenness
(E)

2007         0.826                  0.782
2008         0.753                  0.853

TABLE 2. Avian abundance (percent composition) on burned and unburned
short-grass plots associated with the East Amarillo, Texas Complex
wildfires of 2006.

                                            Short-grass
                                               2007
Species                            named (n = 5)   Unburned (n = 5)

Northern Bobwhite                        0                0
(Colinus virginianus)
Scaled Quail                             0             2 (1.9)
(Callipepla squamata)
Killdeer (Charadrius vociferous)      1 (0.7)             0
Mourning Dove (Zenaida macroura)         0                0
Common Nighthawk                      8 (5.8)          1 (0.9)
(Chordeiles minor)
Scissor-tailed Flycatcher             2 (1.4)          3 (2.9)
(Tyrannus forficatus)
Horned Lark                          31 (22.4)        15 (14.4)
(Eremophila alpestris)
Cliff Swallow                            0             1 (0.9)
(Petrochelidon pyrrhonota)
Barn Swallow (Hirundo rustica)        1 (0.7)          1 (0.9)
Dickcissel (Spiza americana)          2 (1.4)          1 (0.9)
Cassin's Sparrow                      4 (2.9)          2 (1.9)
(Peucaea cassinii)
Grasshopper Sparrow                  33 (23.9)        33 (31.7)
(Ammodramus savannarum)
Lark Sparrow                         26 (18.8)        11 (10.6)
(Chondestes grammacus)
Western Meadowlark                   28 (20.3)        33 (31.7)
(Sturnella neglecta)
Brown-headed Cowbird                  2(l.4)           1 (0.9)
(Molothrus ater)
Common Grackle                           0                0
(Quiscalus quiscula)
Totals                                  138              131

                                             Short-grass
                                                2008
Species                            Burned (n = 5)   Unburned (n = 5)

Northern Bobwhite                     1 (0.8)              0
(Colinus virginianus)
Scaled Quail                             0                 0
(Callipepla squamata)
Killdeer (Charadrius vociferous)      1 (0.8)           1 (0.8)
Mourning Dove (Zenaida macroura)      4 (3.1)           5 (4.3)
Common Nighthawk                      7 (5.3)           5 (4.3)
(Chordeiles minor)
Scissor-tailed Flycatcher             2 (1.5)           4 (3.4)
(Tyrannus forficatus)
Horned Lark                          25 (19.1)         15 (12.9)
(Eremophila alpestris)
Cliff Swallow                         1 (0.8)              0
(Petrochelidon pyrrhonota)
Barn Swallow (Hirundo rustica)        2 (1.5)              0
Dickcissel (Spiza americana)             0                 0
Cassin's Sparrow                      6 (4.6)           6 (5.2)
(Peucaea cassinii)
Grasshopper Sparrow                  27 (20.6)         30 (25.9)
(Ammodramus savannarum)
Lark Sparrow                         21 (16.0)         12 (10.3)
(Chondestes grammacus)
Western Meadowlark                   26 (19.8)         33 (28.4)
(Sturnella neglecta)
Brown-headed Cowbird                   6(4.6)           5 (4.3)
(Molothrus ater)
Common Grackle                         2(l.5)              0
(Quiscalus quiscula)
Totals                                  104                89

Species                            Totals

Northern Bobwhite                   1 (0.2)
(Colinus virginianus)
Scaled Quail                        2 (0.4)
(Callipepla squamata)
Killdeer (Charadrius vociferous)    3 (0.6)
Mourning Dove (Zenaida macroura)    9 (1.8)
Common Nighthawk                    21 (4.3)
(Chordeiles minor)
Scissor-tailed Flycatcher           11 (2.2)
(Tyrannus forficatus)
Horned Lark                        86 (17.6)
(Eremophila alpestris)
Cliff Swallow                       2 (0.4)
(Petrochelidon pyrrhonota)
Barn Swallow (Hirundo rustica)       4(0.8)
Dickcissel (Spiza americana)        3 (0.6)
Cassin's Sparrow                    18 (3.7)
(Peucaea cassinii)
Grasshopper Sparrow                124 (25.3)
(Ammodramus savannarum)
Lark Sparrow                       70 (14.3)
(Chondestes grammacus)
Western Meadowlark                 120 (24.5)
(Sturnella neglecta)
Brown-headed Cowbird                14 (2.9)
(Molothrus ater)
Common Grackle                      2 (0.4)
(Quiscalus quiscula)
Totals                                490

TABLE 3. Avian abundance (percent composition) on burned and
unburned mixed-grass plots associated with the Eas Amarillo, Texas
Complex wildfires of 2006.

                                          Mixed-grass
                                            2007
Species                        Burned (n = 5)   Unburned (n = 5)

Northern Bobwhite                 ( (1 .1)           2(l.5)
Lesser Prairie-Chicken
(Tympanuchus pallidicinctus)         0                 0
Killdeer                             0                 0
Mourning Dove                        0              3 (2.3)
Common Nighthawk                  4 (4.5)           7 (5.3)
Eastern Kingbird                     0                 0
(Tyrannus tyrannus)
Scissor-tailed Flycatcher         3 (3.4)              0
Horned Lark                          0                 0
Cliff Swallow                        0                 0
Barn Swallow                         0              5 (3.8)
Blue Grosbeak                        0              1 (0.8)
(Passerina caerulea)
Dickcissel                        3 (3.4)           3 (2.3)
Cassin's Sparrow                 22 (24.7)         28 (21.1)
Grasshopper Sparrow               9 (10.1)         35 (26.3)
Lark Sparrow                     18 (20.2)         19 (14.3)
Western Meadowlark               25 (28.1)         29 (21.8)
Eastern Meadowlark                   0                 0
(Sturnella magna)
Brown-headed Cowbird              4 (4.5)           1 (0.8)
Bullock's Oriole                     0                 0
(lcterus bullockii)
Totals                               89               120

                                             Mixed-grass
                                             2008
Species                        Burned (n = 5)   Unburned (n = 5)

Northern Bobwhite                  2(l.7)            6(4.3)
Lesser Prairie-Chicken
(Tympanuchus pallidicinctus)      1 (0.8)              0
Killdeer                           2(l.7)              0
Mourning Dove                      2(l.7)          16 (11.4)
Common Nighthawk                 12 (10.0)          7 (5.0)
Eastern Kingbird                  1 (0.8)              0
(Tyrannus tyrannus)
Scissor-tailed Flycatcher         2 (1.7)           3 (2.1)
Horned Lark                          0              1 (0.7)
Cliff Swallow                        0              3 (2.1)
Barn Swallow                      1 (0.8)              0
Blue Grosbeak                        0                 0
(Passerina caerulea)
Dickcissel                           0                 0
Cassin's Sparrow                 31 (25.8)         27 (19.3)
Grasshopper Sparrow              23 (19.2)         22 (15.7)
Lark Sparrow                     12 (10.0)          12(8.6)
Western Meadowlark               29 (25.2)         30 (21.4)
Eastern Meadowlark                   0              3 (2.1)
(Sturnella magna)
Brown-headed Cowbird               2(l.7)           8 (5.7)
Bullock's Oriole                     0              2 (1.4)
(lcterus bullockii)
Totals                              133               140

Species                        Totals

Northern Bobwhite               11 (2.3)
Lesser Prairie-Chicken
(Tympanuchus pallidicinctus)    1 (0.2)
Killdeer                        2 (0.4)
Mourning Dove                   21 (4.4)
Common Nighthawk                30(6.2)
Eastern Kingbird                1 (0.2)
(Tyrannus tyrannus)
Scissor-tailed Flycatcher       8 (1.7)
Horned Lark                     1 (0.2)
Cliff Swallow                   3 (0.6)
Barn Swallow                     6(l.2)
Blue Grosbeak                   1 (0.2)
(Passerina caerulea)
Dickcissel                      6 (1.2)
Cassin's Sparrow               108 (22.4)
Grasshopper Sparrow            89 (18.5)
Lark Sparrow                   61 (12.7)
Western Meadowlark             113 (23.4)
Eastern Meadowlark              3 (0.6)
(Sturnella magna)
Brown-headed Cowbird            15 (3.1)
Bullock's Oriole                 2(0.4)
(lcterus bullockii)
Totals                            482
Gale Copyright: Copyright 2012 Gale, Cengage Learning. All rights reserved.