BLM Technical Note 432

Raptor Nesting Near Oil and Gas Development:

An Overview of Key Findings and Implications

for Management Based on Four Reports

by HawkWatch International

BLM
BLM/WY/ST-10/007+1110
Mark R. Fuller

U.S. Geological Survey

Forest and Rangeland Ecosystem Science Center

970 Lusk St., Boise, Idaho 83706

BLM Technical Note 432

Raptor Nesting Near Oil and Gas Development:

An Overview of Key Findings and Implications

for Management Based on Four Reports

by Hawk Watch International

Prepared for:

U.S. Department of Interior, 

Bureau of Land Management

Utah State Office, Salt Lake City

Colorado State Office, Denver, and

Wyoming State Office, Cheyenne

iii Raptor Nesting Near Oil and Gas Development • BLM Technical Note 432

Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Summary of HWI Reports . . . . . . . . . . . . . . . . . . 5

An Assessment of the Effects of Oil and Gas

Field Activities on Nesting Raptors in the

Rawlins, Wyoming and Price, Utah Field 

Offices of the Bureau of Land Management . . . . 5

Artificial Nest Structures as Mitigation for

Natural-Gas Development Impacts to

Ferruginous Hawks (Buteo regalis) in

South-Central Wyoming . . . . . . . . . . . . . . . . . . . . 9

Accipiter Use of Pinyon–Juniper Habitats for

Nesting in Northwestern Colorado . . . . . . . . . . . 9

Recommendations for Improved Raptor

Nest Monitoring in Association with

Oil and Gas Development Activities . . . . . . . . . 10

Implications From the Four Reports . . . . . 11

Table of Contents

1 Raptor Nesting Near Oil and Gas Development • BLM Technical Note 432

• Artificial Nest Structures as Mitigation for

Natural-Gas Development Impacts to

Ferruginous Hawks (Buteo regalis) in

South-Central Wyoming. TN-434

• Accipiter Use of Pinyon–Juniper Habitats for

Nesting in Northwestern Colorado. TN-435

• Recommendations for Improved Raptor

Nest Monitoring in Association with

Oil and Gas Development Activities. 

TN-436

The results of the projects will be most meaningful if read 

in full with the methodology and discussion offered by 

HWI. 

This is an overview of key findings about the 

effectiveness of stipulations used to manage the potential 

effects of disturbance to raptor nesting in areas where 

oil and gas are being extracted from Bureau of Land 

Management (BLM) lands in Utah, Wyoming, and 

Colorado. These findings come from research by 

HawkWatch International, Inc. (HWI) and provide 

information for management decisions about land 

where oil and gas (OG) extraction occurs or might 

occur on public lands. HWI identified factors that fairly 

consistently are associated with increases or decreases in 

raptor nest use and activity. 

This overview comprises information from the four BLM 

Technical Notes written by HWI. 

• An Assessment of the Effects of Oil and Gas

Field Activities on Nesting Raptors in the

Rawlins, Wyoming and Price, Utah Field 

Offices of the Bureau of Land Management. 

TN-433 

Purpose

3 Raptor Nesting Near Oil and Gas Development • BLM Technical Note 432

HWI compiled information from federal bureaus, 

state agencies, and industry, and determined how to 

evaluate the effectiveness of spatial and temporal buffer 

restrictions that have been applied within areas of OG 

extraction. HWI used the historical data to describe 

patterns of OG development relative to raptor nests, and 

to document changes in the distribution and breeding 

status of raptor nests relative to OG activities. HWI 

evaluated how these historical datasets were useful for 

quantifying the relationship between OG development 

and other human activities and nesting raptors. HWI 

assessed changes in Ferruginous Hawk (Buteo regalis) 

nesting success and productivity, and in use of artificial 

nest structures (ANSs), which had been erected to reduce 

the use by raptors of OG structures as nest substrates. 

Also, HWI studied Accipiter species’ use of pinyon–

juniper vegetation communities in the Piceance Basin 

of Colorado, described basic vegetation and landscape 

characteristics of nests, and offered recommendations 

about surveying for accipiter hawks in pinyon–juniper 

landscapes. Please read the HWI reports for details.

The project was undertaken because of a paucity of 

information about the possible effects of OG operations 

and resource management on nesting raptors. BLM 

raptor management has included stipulations that 

restricted human activity near raptor nests during the 

raptor nesting season. The BLM and the Department of 

Energy (DOE), which provided financial support for the 

study, seek information that will contribute to enhancing 

OG extraction operations while providing environmental 

protection, including raptor conservation. 

This project used historical data from Utah and Wyoming. 

The Price, Utah study area, as of 2006, contained more 

than 1,100 wells, in a nearly uniform distribution at a 

density of one per quarter section (160-acre spacing). 

Some development occurred closer to existing nests 

because the nest sites had not been discovered or because 

the land is administered by the State of Utah, without 

these stipulations. The Rawlins, Wyoming study area 

included more than 4,200 OG wells in 2006. Compared to 

the Price study area, wells at Rawlins were less regularly 

distributed; reaching densities of one well per quarter 

section (160-acre spacing) in some areas, but less dense 

elsewhere. 

Background

5 Raptor Nesting Near Oil and Gas Development • BLM Technical Note 432

An Assessment of the Effects of Oil 

and Gas Field Activities on Nesting

Raptors in the Rawlins, Wyoming 

and Price, Utah Field Offices of the 

Bureau of Land Management. 

Jeff P. Smith, Steve J. Slater, 

and Mike C. Neal

The goal was to assess protective spatial and temporal 

buffers and provide guidance to minimize potential 

disturbance to raptors nesting near OG activities. 

HWI uses “development” to refer collectively to factors 

(e.g., wells and roads) associated with the development 

and maintenance of OG extraction. A nest cluster was 

a group of proximate individual nests that likely were 

alternative nests maintained by one pair using the 

immediate vicinity. The nest cluster associated with an 

individual breeding pair was a single sample unit. 

Two overlapping classifications account for uncertainties 

inherent in the historical data about reproduction attempts 

and the status of nests. HWI conducted separate analyses 

to evaluate two categories of nest status:

The first category type was “used” = evidence 

of recent nest tending, occupation or actual 

breeding, or “unused” = no such evidence 

obtained.

The second category type was “active” = 

breeding attempt confirmed (i.e., egg or nestling), 

or “other”= all other cases, including some used 

(i.e., evidence of tending, but not actual breeding) 

and all unused classifications.

HWI measured the distance from a nest cluster centroid 

or an active nest to wells or roads and analyzed these 

distances relative to nest status categories. Most 

measurements including coverage of various vegetation 

types (e.g., black sagebrush, juniper) were made 

within two spatial scales: 0.8-km and 2.0-km of nests, 

to correspond to typical nest protections in the study 

areas, and to encompass the majority of the study 

species’ home ranges, respectively. HWI designated 

development “hotspots” as areas with well densities 

>0.6 per square km (>1.2 wells within a 0.8-km radius) 

by 2006, and continual additional OG development 

since 1998.

The number of nest clusters of a species, number of well 

sites, and associated features varied depending on the 

relationships being analyzed. For many analyses the 

number was the sum of all the nests in all the years. HWI 

used standard statistical procedures and Geographic 

Information System (GIS) software to analyze spatial 

relationships among development and nest clusters. HWI 

used multiple regression to analyze the proportion of 

years nest clusters surveyed a minimum of 5 years were 

used during OG development and to investigate whether 

the status of nest cluster was affected by OG 

development.

Using data that resulted from analyzing relationships 

among nest cluster use and development and between nest 

cluster activity and development, HWI added vegetation 

and climate factors to determine the relationships between 

use, activity, and development, after accounting for the 

potential influence of vegetation and yearly climate. This 

modeling included combinations of parameters and 

predictor variables. They also modeled Ferruginous 

Hawk nest success and productivity, and nesting on ANSs 

relative to these variables and to nest accessibility. For 

each species and study area, HWI presented the top 

models (i.e., the most likely models based on accepted 

model selection procedures, given the data under 

consideration) from many possible models. HWI reminds 

the reader: “...it must be noted that all results derived 

from this investigation serve only to reveal potential 

correlations between OG development and raptor nesting 

activities; i.e., cause-effect inferences cannot be 

assumed.” HWI provides interpretations of those results 

deemed most important.

This overview contains more details from the results and 

discussion associated with Golden Eagle (Aquila 

chrysaetos) nests in the Price study area than for other 

species or for the Rawlins area. In this overview, 

information about other species and the Rawlins area is 

drawn largely from the report discussion. Please read the 

HWI report to learn about the methods used, to see many 

additional results, and to consider discussion of the 

results. 

Price, Utah Study Area

The average density of OG wells proximate to raptor 

nest clusters increased three to four-fold at the 0.8 and 

2.0-km scales from 1998–2006, and the average distance 

Summary of HWI Reports
6 BLM Technical Note 432 • Raptor Nesting Near Oil and Gas Development

to the nearest well decreased by roughly 20 percent. 

The number of nest clusters distant from wells was 

decreasing, and by 2006, 71 percent of nest clusters had 

no wells within 0.8 km and, 54 percent had no wells 

within 2.0 km.

Golden Eagle

HWI reports extensive results that reveal complex 

relationships among the factors included in their analyses. 

During the greatest OG development expansion (1999–

2002), Golden Eagles used nest clusters that were farther 

from OG development hotpots than were unused clusters; 

however, this tendency diminished as new development 

subsided in the hotspots after 2002. This suggests that: 

1) the development of new well sites temporarily deterred 

some Golden Eagles from nesting, and 2) some Golden 

Eagles habituated to established wells and associated 

maintenance.

Golden Eagle nest cluster use and activity varied 

between the 0.8-km and 2.0-km scale depending on 

development and vegetation factors, and with the Palmer 

Drought Severity Index (PDSI). Decreased drought 

severity, during a preceding year and the current year, 

was correlated with increased Golden Eagle nest cluster 

activity. 

As more OG development occurred, Golden Eagle nest 

cluster use decreased, and nesting activity declined within 

0.8 km. Golden Eagle nest cluster use increased within 

2.0 km, as did activity within 0.8 km and 2.0 km, when 

there was a greater density of primary and secondary 

roads (i.e., roads that were not constructed to access OG 

well sites). A significant interaction existed between 

development factors and vegetation factors in models of 

the birds’ nest cluster use and activity. For example, the 

models suggested that the probability of Golden Eagle 

nest clusters being used or active in May increased as: 

• overall OG development decreased near clusters

• the prevalence of non-OG roads increased at the 

2.0-km scale

• drought severity decreased

• cover of mountain, basin big, and black sagebrush 

increased

• pinyon and juniper decreased 

• human infrastructure and rabbitbrush decreased 

Between 1998 and 2006 the likelihood that a nest 

cluster was used was greater where the types of OG 

development varied or where there was high diversity 

of OG development levels among alternative nests 

within clusters. This might be another indication that 

Golden Eagles respond differently to various types of 

development, and that when alternative nest sites exist, 

the birds can choose a site where they are less disturbed. 

Golden Eagle proportional nest use increased in areas of: 

• mountain or basin big sagebrush, mountain shrub, 

conifer, and aspen, and high proportions of black 

sagebrush cover 

• relatively high proportion of open water 

Proportional nest use decreased in areas of: 

• high pinyon-juniper and Wyoming or mixedspecies sagebrush cover

• rabbitbrush, and riparian forest cover

• high human habitation 

Golden Eagle proportional nest activity was greater in 

areas where 

• extents of non-OG roads were more diverse at 

the 0.8-km scale among alternative nests within 

clusters 

• cover of pinyon-juniper and barren lands within 

2 km was low

• cover of desert shrub and agricultural habitats 

was relatively high 

These proportional use models resulted in some 

relationships that when considered with other results 

reveal consistently positive factors (e.g., black sagebrush) 

and negative factors (e.g., human habitation) for Golden 

Eagle nest use and activity. HWI reiterated that the 

discrimination ability of the proportional use/activity 

models was low, and hence “these results must be 

considered with great caution.” However, these results 

reveal characteristics of the environment with which to 

experiment for enhancing nest use and activity.

Red-tailed Hawk

These results suggest that the probability of Red-tailed 

Hawk (Buteo jamaicensis) nest clusters being used 

increased in association with development within 0.8 

km of the cluster, but decreased with OG development 

within 2.0 km. Additionally, use increased in habitats 
7 Raptor Nesting Near Oil and Gas Development • BLM Technical Note 432

dominated by a mix of mountain and basin big sagebrush 

cover, but decreased in habitats dominated by a mix of 

pinyon, juniper, and mixed-species sagebrush. The results 

for active clusters were similar and suggest that the 

relationships of development and nesting are modified by 

spatial scales and vegetation.

Prairie Falcon

Using only metrics of development, models of Prairie 

Falcon (Falco mexicanus) nest cluster use and activity 

data revealed no relationships to the development factors. 

Nest cluster use and activity were positively related to 

desert shrub and agricultural cover, but negatively related 

when relatively high cover of riparian forest, grass, forbs, 

and black sagebrush or pinyon, pinyon-juniper mix, and 

barren lands occurred. More activity at nest clusters was 

suggested with decreasing drought severity, but excessive 

winter precipitation might be detrimental. 

Price area summary

HWI summarized some results as “patterns” for the Price 

study area, including:

•	 Price Golden Eagle data produced consistent 

negative relationships within 0.8 and 2.0 km of 

OG development.

•	 Red-tailed Hawk data produced mixed 

relationships with OG development; suggesting 

a benefit from some OG development within 0.8 

km of nest clusters, but a diminished or reversed 

relationship to OG development within 2.0 km. 

•	 The top Golden Eagle and Red-tailed Hawk 

model results suggested positive associations 

with non-OG roads, depending on the spatial 

scale.

•	 Use of the drought index revealed a generally 

positive effect of wetter conditions, as long as 

pre-nesting moisture was not extreme.

Rawlins, Wyoming Study Area

The number of wells increased from 1,438 to 4,258 

between 1978 and 2006, most dramatically from 1978–

1985 to 1994–2006. The total length of roads within 2.0 

km of nest clusters increased significantly between 1978 

and 2006, and the distance between nest clusters and OG 

wells decreased significantly, while the number of nearby 

wells increased significantly. The percentage of nest 

clusters with no wells nearby declined by 9 percent at the 

0.8-km scale (from 95 percent to 86 percent) and 

12 percent at the 2.0-km scale (from 86 percent to 

74 percent).

Golden Eagles

The model using only development factors suggested that 

Golden Eagle nesting activity was negatively related to 

OG development within 0.8 and 2.0 km, and positively 

related with non-OG roads at the 2.0-km scale. Nest 

cluster use did not appear to be affected by development 

after accounting for vegetation and climate, although 

there was an indication that increasing OG development 

within 2.0 km of nest clusters was associated with 

decreasing nest activity. Integrating development, 

vegetation, and climate factors suggested that nest use 

and activity were: 

• greater during periods of drought recovery

• positively related to greater cover of riparian 

forest, grass, mountain mahogany, agriculture, 

and less high-growing sagebrush species 

The results from proportional Golden Eagle nest use and 

activity suggested that the proportion of years in which 

clusters were used or active increased:

• with relatively stable OG development,

• when alternative nests allowed eagles to change 

nesting locations relative to non-OG roads

Ferruginous Hawks

In the Rawlins study area, Ferruginous Hawks used a 

variety of nest substrates that included OG structures 

(mostly condensation tanks) and ANSs. Since 1987, the 

BLM has erected ANSs to discourage Ferruginous Hawks 

from nesting on oil and gas infrastructure.

Regarding nests that were not on ANSs, the models 

suggest that nest cluster use and activity were greater 

with less OG development and proportionately more 

non-OG roads within 0.8 km, but that these relationships 

diminished at the 2.0-km scale. When vegetation and 

climate were modeled with development, only nestcluster activity in the 0.8-km radius of the nest had a 

negative relationship with OG development. Some use 

and activity models suggested a positive relationship 

with non-OG roads at the 0.8-km scale, but a negative 

relationship at 2.0-km. The positive relationships 

between non-OG roads within 0.8 km and non-ANS 

cluster use and activity increased when there was more 
8 BLM Technical Note 432 • Raptor Nesting Near Oil and Gas Development

evergreen forest cover, but less Wyoming big sagebrush 

or agriculture. The proportional use and activity models 

also suggested a negative effect of OG development 

within 0.8 km of nest clusters, and a positive effect of 

non-OG roads at the 0.8-km scale.

Artificial nest structures often were erected within 1 

km of where Ferruginous Hawks had constructed nests 

on OG facilities such as a condensation tank; thus, 

the majority of ANSs were near OG development. 

Ferruginous Hawk nest use and activity had a positive 

relationship with OG development at both spatial scales, 

and were positively related to non-OG roads at the 2.0-km 

scale. Positive relationships between OG development 

and ANS use and activity were enhanced by more riparian 

forest, grass, mountain mahogany, or agriculture. HWI 

notes, “Perhaps most importantly, compared to many 

natural-substrate nests, all ANSs were inaccessible from 

the ground and likely provided nesting birds with a 

sense of security in the face of development activities... 

inaccessible nests were nearly always successful, and 

therefore nearly all such nests were at least minimally 

productive.”

Red-tailed Hawks 

Relationships between development alone and annual 

nest cluster use and activity indicated negative Redtailed Hawk responses to OG development within 2.0 

km of nests. Incorporating development, vegetation, and 

climate in models revealed that nest use was influenced 

by development levels, but nest activity was not. Redtailed Hawk cluster use was negatively related to OG 

development within 0.8-km, but positively related at 

the 2.0-km scale, suggesting that the negative effects of 

OG development diminished with distance. However, 

cluster use was negatively related to non-OG roads within 

2.0 km. Red-tailed Hawks in Rawlins also responded 

positively to reduced drought severity, and to greater 

cover of riparian forest, grass, mountain mahogany, and/

or agriculture.

Prairie Falcons

Prairie Falcon nest cluster use and activity had a negative 

association with increased OG development and the 

extent of and proximity to non-OG roads. HWI suggests 

that Prairie Falcons might have been the most sensitive 

to general human activities of the four species it studied. 

When vegetation and climate variables were modeled 

with OG and development, the result again was a negative 

relationship of annual Prairie Falcon nest use and activity 

with OG development and non-OG roads. The negative 

association of OG development increased with more 

barren land, but diminished with relatively high cover of 

Wyoming big sagebrush.

Rawlins area summary

Use or activity models for the four species in the 

Rawlins study area resulted in negative relationships at 

various scales with OG development factors, except for 

Ferruginous Hawk nesting on ANSs: 

• Development and vegetation interacted variously 

among species and measurement scales to 

influence raptor nest use and activity. 

• Vegetation relationships were complex for each 

raptor species, but all had positive relationships 

that suggest enhanced nesting in the presence 

of riparian forest, grass, mountain mahogany, or 

agricultural cover in the surrounding landscape, 

which might reflect productive bottomland, 

drainage areas, and agricultural uses.

Conclusions and Management 

Implications

The results from modeling only the relationships among 

raptor nest cluster use and nest cluster activity with 

development often differed from those resulting from 

including climate and vegetation variables in a model. 

This indicates the importance of considering factors 

of other human influences, vegetation, climate, etc., 

when evaluating the potential effects of OG activities 

near nests. HWI reminds the reader that the results are 

potential correlations between OG development and 

raptor nesting and that cause-effect inferences cannot be 

assumed.

HWI concludes that there were consistent results 

of negative relationships of OG development in the 

Price and Rawlins study areas after accounting for the 

occurrence of vegetation and climate conditions. Only 

Ferruginous Hawks using ANS exhibited consistent 

positive relationships among nest use and nest activity 

and OG development factors. The data were insufficient 

to determine if the apparent negative effects of 

development were associated with raptor population 

characteristics such as fledging young from the nest or a 

trend in numbers of nesting raptors. 

HWI suggests that existing nesting-season protection 

buffers of 0.8-km radius should not be reduced, 

because the four focal raptor species exhibited negative 

relationships with OG development that occurred 

within 0.8 km of nest clusters. At the 2.0-km spatial 
9 Raptor Nesting Near Oil and Gas Development • BLM Technical Note 432

in areas of low overall OG development and where 

primary and secondary road occurrence was high within 

0.8 km but low at the 2.0 km scale. 

HWI considered a nest or an ANS 2.5 m above ground 

to be inaccessible to human disturbance and predators. 

Accessibility was a predictor of nest success. The most 

“successful” category of nests was natural-inaccessible, 

followed by manmade-inaccessible, manmade-accessible, 

and least successful were accessible nests on natural 

substrates. HWI concluded that Ferruginous Hawks in 

the study area responded to ANSs and were successful on 

them, and this likely was due to ANSs providing a secure 

nesting location within foraging habitat that previously 

lacked secure natural nest sites.

The results from this research indicate that ANSs may be 

an effective mitigation tool where Ferruginous Hawks are 

nesting on inappropriate man-made structures, but HWI 

also suggests:

•	 Extensive use of ANSs could create a “population 

sink” wherein Ferruginous Hawks are attracted 

to nest sites, but then incur detrimental effects 

associated with use of the area. 

• Studying post-fledgling survival, foraging-range 

habitat use, and long-term population growth and 

recruitment in comparison to an area where ANSs 

are not used. 

• The extensive use of ANSs as mitigation must 

be accompanied by a long-term commitment to 

their maintenance to avoid a situation in which a 

large proportion of a nesting population becomes 

dependent on nest structures that eventually are 

unavailable.

Accipiter Use of Pinyon–Juniper 

Habitats for Nesting in Northwestern

Colorado.

Steven J. Slater and Jeff P. Smith

BLM biologists documented nesting by three hawk 

species of the genus Accipiter in the Piceance Basin, 

Colorado in pinyon–juniper vegetation, which is an 

extensive cover type that previously had been largely 

overlooked as potential nesting areas for such species. 

The objectives of the HWI research were to survey 

for the hawks, and describe vegetation and landscape 

scale, negative relationships were found between OG 

development and Price-area Golden Eagles and Rawlinsarea Golden Eagles and Prairie Falcons. The Golden 

Eagle results presented in this overview provide examples 

of the complexity of relationships among raptor nesting, 

OG development, and other environmental factors. 

As noted, these results reveal characteristics of the 

environment with which to experiment for enhancing 

raptor nesting. Many additional examples of results that 

provide a basis for developing additional management 

practices can be found in the report.

Artificial Nest Structures 

as Mitigation for NaturalGas Development Impacts to 

Ferruginous Hawks (Buteo regalis) 

in South-Central Wyoming. 

Mike C. Neal, Jeff P. Smith, 

and Steven J. Slater

Ferruginous Hawks were documented nesting on naturalgas structures in the Rawlins BLM district during the 

1980s. Nests on structures such as condensation tanks 

commonly failed, so the BLM staff installed 105 artificial 

nest structures (ANS) from 1987 to 2004 to provide the 

hawks with alternative nest substrates. This report draws 

upon results presented in the lead author’s thesis (M. 

Neal, University of Wyoming, 2007) and the previous 

Assessment report (above) to evaluate the efficacy of 

ANSs as a mitigation tool for Ferruginous Hawks nesting 

in areas of OG development.

HWI termed “active” nests as those where reproductive 

behavior (e.g., copulation, incubation, brooding, or nest 

attendance) was observed. Evidence of “occupied” nests 

included the observation of one or more hawks in the 

immediate vicinity of the nest or signs of hawk presence 

(e.g., recent nest material, prey remains) during the 

breeding season. From BLM records, HWI used 417 nest 

clusters and 1,234 nests in the analyses. Of these 1,234 

nests, 750 (61 percent) occurred at 89 different ANSs, 88 

(7 percent) at 13 other manmade nest substrates, and 396 

(32 percent) at 315 natural-substrate nests (e.g., rockysubstrate, the ground on hillside, nests in evergreen-tree).

The nesting distribution of Ferruginous Hawks shifted 

to ANS, and active nests were closer to developmenthotspot centers than inactive nests. Results from modeling 

indicated that nesting on other substrates only increased 
10 BLM Technical Note 432 • Raptor Nesting Near Oil and Gas Development

characteristics of nests. Surveys involved broadcasting 

vocalizations of each species from stops along unpaved 

roads in areas of large stands of pinyon-juniper cover, and 

subsequent searches on foot to find new nest structures 

and visit historical nest sites. 

Accipiters often flew toward survey stops before the birds 

were detected, and detections occurred as far as 540 m 

from nests. Nest-site characteristics of the three species 

commonly overlapped and each used pinyon and juniper 

trees for nesting in pinyon–juniper patches of at least 4.8 

ha. The relatively small Sharp-shinned Hawk (Accipiter 

striatus), medium sized Cooper’s Hawk (A. cooperii), 

and large Northern Goshawk (A. gentilis) used nest sites 

with similar average canopy cover (64–65 percent) and 

densities of live trees between 23–38 cm DBH (168–175 

trees/ha). Most commonly, nests were found on sloped 

terrain facing from northwest to east.

The surveys by the BLM and HWI have revealed an 

unexpected abundance of nesting accipiters in pinyonjuniper vegetation. Because federal lands are estimated 

to contain 65 percent of current pinyon-juniper cover, 

HWI recommends that accipiters be included when 

planning land management in this vegetation type. 

Recommendations for survey methods are provided in the 

report (p. 9-11).

Recommendations for Improved 

Raptor Nest Monitoring in 

Association with Oil and Gas 

Development Activities. 

Jeff P. Smith, Steven J. Slater, 

and Mike C. Neal

The BLM and the DOE wanted to evaluate raptor nesting 

in areas of OG exploration and extraction. The BLM and 

industry had gathered information about raptor nesting 

occurrence and OG development, and HWI used this 

information and gathered new material for evaluating 

the relationships among development and raptor nest 

use. HWI found that some historical information was 

inadequate for use in addressing BLM and DOE interests. 

Some of the problems HWI encountered to varying 

extents included:

•	 Terms and phrases used to label data often were 

not defined or used consistently within or among 

study areas. 

• Inadequately documented (e.g., what was 

observed, when, or where) survey records.

• Lack of pre-development, baseline monitoring 

data. 

• Little survey effort in areas not affected by that 

development (i.e., no control area data). 

• Vague identification of nest locations.

• No report of the raptor species using the nest. 

• Inconsistent data gathering (e.g., not surveying a 

nest cluster some years, not gathering the same 

information through time). 

• A paucity of data about clutch and brood sizes.

• Insufficient information about the timing and 

extent of OG activities. 

• Few current maps of existing road networks, 

accurate and current well-pad roads, and current 

powerline data.

The full report by HWI contains detailed 

recommendations to guide future monitoring of nesting 

raptors in conjunction with OG development. Included 

are key procedures that would facilitate more informative 

future evaluations:

•	 Training persons to conduct survey protocols. 

• Regular use of Global Positioning System (GPS) 

technology. 

• Budgeting time and personnel for regular entry of 

data and detailed metadata to electronic archives. 
11 Raptor Nesting Near Oil and Gas Development • BLM Technical Note 432

• Conduct surveys to document raptor nesting 

and associated environmental factors in areas 

unaffected by OG, especially areas where OG 

might occur;

• Implement survey and monitoring of select 

factors (species, vegetation, anthropogenic) at 

OG activity sites and at control sites;

• Gather raptor food habits data, and prey – 

vegetation association data and use results to 

manage habitat for prey;

• Conduct management to conserve and enhance 

existing vegetation that is presumed to be 

beneficial based on these HWI study results;

• Compare Ferruginous Hawk use of ANSs and 

associated survival and reproduction among 

ANSs in OG areas and non-OG areas; 

• Provide ANSs for other species and evaluate their 

use and effectiveness as a mitigation method; 

• Refine time and space stipulations by 

experimentally manipulating when and where OG 

activities occur relative to raptor nesting. 

Spatial and temporal buffer stipulations have contributed 

to raptor conservation in the study areas at Rawlins, 

Wyoming and Price, Utah where oil and gas development 

activities occur. The results of the HWI study reveal that 

OG operations near nests are associated with reduced 

raptor use and activity at nests in many circumstances. 

Sometimes the reductions of use and activity are 

temporary. Presumably, more disturbances would 

occur and there would be less habituation by raptors 

to disturbance if no restrictions had been placed on the 

distance and timing of OG operations near raptor nest 

sites. Consequently, there would have been greater 

reductions of use and activity than what has occurred. 

It could not be determined by HWI if there has been 

a change in the populations of raptors in conjunction 

with oil and gas development. Nonetheless, it can be 

concluded that applying spatial and temporal buffers 

around nests is a useful management practice to continue 

as part of a raptor conservation strategy.

Results from the four reports reveal many aspects of 

the environment that in combination with OG activities 

might influence raptor nesting, and thus have implications 

for management of areas where OG development is 

underway or where it might occur. Anthropogenic 

features other than those resulting from OG development, 

as well as vegetation cover and weather are associated 

with increases and decreases in raptor nest use and 

activity near OG activities. Whether or not the factors 

modeled were associated with more or less raptor nesting 

varied among species, study area, and measurement scale 

(within 0.8 or 2.0 km from nest). 

The BLM can use results from the reports to further 

develop management strategies to conserve raptor nesting 

habitat near OG activities. For example:

• Develop survey designs with thorough, consistent 

methods for monitoring raptor nesting, and 

for monitoring factors that likely affect raptor 

nesting;

Implications From the Four Reports

The mention of trade names or commercial products does not constitute endorsement

or recommendation for use by the Federal Government.
BLM Technical Note 432 Raptor Nesting Near Oil and Gas Development:

An Overview of Key Findings and Implications

for Management Based on Four Reports by

Hawk Watch International 

BLM Technical Note 433 An Assessment of the Effects of Oil and Gas Field 

Activities on Nesting Raptors in the Rawlins, 

Wyoming and Price, Utah Field Offices of the 

Bureau of Land Management

BLM Technical Note 434 Artificial Nest Structures as Mitigation for NaturalGas Development Impacts to Ferruginous Hawks 

(Buteo regalis) in South-Central Wyoming

BLM Technical Note 435 Accipiter Use of Pinyon–Juniper Habitats for 

Nesting in Northwestern Colorado

BLM Technical Note 436 Recommendations for Improved Raptor Nest 

Monitoring in Association with Oil and Gas 

Development Activities

These five documents are an integrated series.