Behneyelal • RAPTOR AND LESSER PRAIRIE-CHICKEN INTERACTIONS 
333 
1988. Haukos and Broda 1989, Hagen and Giesen 
2005. Hagen et al. 2007, Wolfe et al. 2007). 
Specific to our study area. Northern Harriers 
[Circus cyaneus ) have been observed predating 
Lesser Prairie-Chickens in eastern New Mexico 
'Campbell 1950) and the Texas Southern High 
Plains (Haukos and Broda 1989). Our objectives 
were to examine: (1) encounter rates and inci¬ 
dences of raptor predation al Lesser Prairie- 
Chicken leks, and (2) behavioral responses of 
prairie-chickens to different raptor species and 
Chihuahuan Ravens (Corvus cryptoleucus) at leks 
in the Texas Southern High Plains. 
METHODS 
Study Area —Our study occurred on private 
lands in Cochran and Yoakum counties in the 
Texas Southern High Plains ecoregion (Llano 
Eslacado). The topography is Hat to gently 
undulating with small vegetated dunes. The 
dominant vegetation in most areas was shinnery 
oak (Quereus havardii) intermixed with sand 
sagebrush (Artemisia filifolia ) and grasses. The 
major land use in this area was agriculture with a 
high proportion of the area under intensive 
cultivation and cattle production. Oil development 
occurred throughout the study area with Yoakum 
County producing 23,730,647 barrels of oil in 
-007 (Railroad Commission of Texas 2010). 
f/eW Methods .—We used a combination of 
direct observation and video-recording to monitor 
ra Ptor-lesser Prairie-Chicken encounters at leks 
during spring 2007 and 2008. We used four leks 
known by landowners and Texas Parks and 
Wildlife Department staff in 2007, and included 
>hree new leks located hy roadside surveys in 
’008 (Behney 2009). We excluded two of the 
7007 leks due to logistical constraints in 2008. 
Direct observations were conducted from small, 
camouflaged, pop-up style blinds placed among 
' cgeiation at the edge of the Ick, or from a vehicle 
parked within 15 m of the Ick. We arrived al leks 
before prairie-chickens were present: typically 
^1-5 hrs before sunrise and remained stationary 
,or the duration of the observation period. Wc 
used binoculars and spotting scopes to monitor 
prairie-chickens and identify predators. We did 
n °t depart the lek until 20 min after the last 
prairie-chicken departed each morning. 
We placed two video-recording systems at each 
lek being video-monitored. One system was 
Placed sufficiently far from the lek to ensure the 
entire area was recorded (far) and the second 
system was placed close to or zoomed in (close) to 
record behaviors of grouse and predators. This 
camera arrangement was not possible on one lek 
and we used two camera systems placed the same 
distance from the lek but at different angles. 
Each video-reeortling system consisted of a 
security style camera connected to a video camera 
recorder (VCR) or digital video camera recorder 
(DVDR). Camera systems were powered by a 12- 
volt deep-cycle marine battery connected to a 
power inverter, and enclosed in weatherproof 
housing. A power suip was connected to the 
inverter, into which the VCR and the security 
camera were connected. The VCR or DVDR 
recorded real-time video to facilitate identification 
of flying raptors and behavior of prairie-chickens. 
Recording occurred 2—4 days/week at each lek. 
We recorded lek activities from 0.5 hrs before 
sunrise to 2-4 hrs post-sunrise and from 2 hrs 
before sunset to 0.5 hrs after sunset. All tape and 
battery changes were at mid-day (1100-1400 hrs) 
when prairie-chickens were not present to mini¬ 
mize risk of disturbance. We used an editing VCR 
to review the collected video footage of activities 
at leks. Wc initially viewed the far camera 
recordings to identify behaviors (predator, flush¬ 
ing. disturbance) and then viewed the close up 
tape for a more in-depth view. We reviewed both 
tapes completely in the case where two cameras 
were placed the same distance from the lek. 
Wc noted the time, date, lek, species, age (if 
possible), raptor approach type, and prairie- 
chicken response type if a raptor or raven was 
observed. The raptor or raven had to be within 
35 m of the lek (visually estimated) to be included 
in the analysis. At this distance the raptor or raven 
and Lesser Prairie-Chickens should have been 
able to sec each other. Wc classified raptors to the 
lowest taxonomic level possible when we could 
not identify the raptor species. We pooled 
Peregrine Falcon (Falco peregrinus'), Prairie 
Falcon (F. mexicanus). Merlin (f columbarius). 
and unknown falcons (Falco spp.) in a “falcon 
group and Red-tailed Hawk [Buteo jomaicensis ), 
Ferruginous Hawk ( B. regal is), and unknown 
buteos (Buteo spp.) in a “buteo” group. We 
pooled Cooper’s Hawks (Accipiter cooperii) and 
Sharp-shinned Hawks (A. striatus ) into an “ac- 
cipiter" group. 
Statistical Analysis.— Raptor approach types 
were classified as predation attempt, course, 
perch, or fly-by. “Predation attempts” were 
obvious dives at or chases of Lesser Prairie- 
