Annual breeding bird surveys have been conducted on
the Idaho National Laboratory (INL) since 1985 (no surveys were
conducted in 1992 and 1993) to monitor bird populations. In 2007,
surveys were conducted in late May and early June along 13
permanently established routes, five of which are part of the U.S.
Geological Survey’s nationwide program and eight around facilities
specific to the INL. A total of 5,412 birds were observed during the
2007 survey which is slightly above the 1985-2007 average of 4,991
birds. A total of 69 different species were documented during the
2007 BBS which is above the average of 59 species recorded since
Similar patterns of species abundance were found with horned lark (Eremophila
alpestris; n = 1416) the most abundant species in 2007 and
previous years. Western meadowlark (Sturnella neglecta; n =
987), Brewer’s sparrow (Spizella breweri; n = 528), sage
sparrow (Amphispiza belli; n = 459), and sage thrasher (Oreoscoptes
montanus; n = 410) constitute the next four most abundant
species. In the 21 years of INL breeding bird surveys, these five
species have been the most abundant 16 times, and are among the six
most abundant species recorded in all years. Considering the
declines observed in sagebrush obligate species throughout the
intermountain west, this trend of abundance suggests the quality of
INL sagebrush steppe habitat remains high.
The 2007 survey yielded four species never recorded during the INL
survey. A single observation of a greater scaup (Aythya marila),
bald eagle (Haliaeetus leucocephalus), osprey (Pandion
haliaetus), and turkey vulture (Cathartes aura) was made
this year. This is the first documented field observation of a bald
eagle observed on INL during spring.
Species observed during the 2007 BBS that have been assigned an
Idaho state ranking of critically imperiled or imperiled include
greater sage-grouse (Centrocercus urophasianus; n=4),
ferruginous hawk (Buteo regalis; n=8), long-billed curlew (Numenius
americanus; n=7), Franklin’s gull (Larus pipixcan;
n=178), Brewer’s sparrow (n=528), and the grasshopper sparrow (Ammodramus
The North American Breeding Bird Survey (BBS) was
developed by the U.S. Fish and Wildlife Service (USFWS) in
conjunction with the Canadian Wildlife Service to initiate the
collection of data to document bird population trends. Pilot surveys
began in 1965 and immediately expanded to cover the U.S and Canada
east of the Mississippi and by 1968 included the entire North
American Continent (Bystrak 1981, Robbins et al. 1986). The North
American BBS program is managed by the U.S. Geological Survey (USGS)
and currently consists of over 4100 routes with approximately 3000
sampled each year.
BBS survey data continue to provide some of the only long-term bird
population information covering broad geographic scales. These data
have been used to estimate population changes for hundreds of bird
species, and remain the primary data source for regional
conservation programs and modeling efforts (Sauer et al. 2003).
Numerous statistical pathways for exploring and analyzing BBS data
have been proposed and discussed amongst researchers (James et al.
1996, Link and Sauer 1997, McCulloch et al. 1997, Bart et al. 2004,
Sauer et al. 2005). Regardless of differences in opinion concerning
the most appropriate analysis techniques, the BBS undeniably
provides a wealth of information about North American bird
population trends that form the foundation for broad conservation
assessments extending beyond local jurisdictional boundaries.
The Idaho National Laboratory (INL) has five permanent official BBS
routes originally established in 1985 (hereafter referred to as
remote routes) and eight additional survey routes around INL
facilities (hereafter referred to as facility routes). The facility
routes were developed to monitor avifauna populations in proximity
to anthropogenic activities and disturbances. The annual BBS survey
provides land managers with breeding bird population trend
information relative to the activities conducted on the INL. This
report summarizes the results from the 2007 BBS survey, and compares
observed species abundance across survey routes with long-term
The INL is a Department of Energy facility
encompassing almost 900 mi2 (2315 km2) located on the Upper Snake
River Plain in southeast Idaho (Figure 1). The INL was designated as
a National Environmental Research Park in 1975 to facilitate field
research assessing environmental impacts from nuclear energy
development technologies. The INL lies within portions of Bingham,
Bonneville, Butte, Clark, and Jefferson counties.
Topography across the INL is mostly flat with an average elevation
of 4985 ft (1520 m) above sea level. Other than minor topographic
variation created by basalt outcrops, the only significant relief
occurs around East and Middle Buttes and the southern extent of the
Lemhi mountain range located on the northwest corner of the INL.
Anderson et al. (1996) provide a detailed description of the
climate, geology, and vegetation communities found on the INL. In
general, the INL is located in a semi-arid desert that experiences
hot, dry summers and cold winters. Annually the INL receives on
average eight inches (20 cm) of precipitation with a peak common in
the spring. The geology is dominated by Quaternary basalt lava flows
producing the outcrops and lava tubes found across the site today.
Aeolian soils consisting primarily of silt loam and sandy loam are
the most common soil type found throughout the INL, while alluvial
soils are more commonly found along the Big Lost River flood plain.
The INL is a shrub-steppe ecosystem dominated by a woody shrub
overstory and perennial bunchgrass and forb understory. Wyoming big
sagebrush (Artemisia tridentata wyomingensis) is the most dominant
shrub on the INL, while other sagebrush species, green rabbitbrush (Chrysothamnus
viscidiflorous), spiny hopsage (Grayia spinosa) shadscale (Atriplex
confertifolia) and winterfat (Krascheninnikovia lanata) can be
commonly found. The most common native grasses include thickspiked
wheatgrass (Elymus laceolatus), bottlebrush squirreltail (Elymus
elymoides), Indian ricegrass (Achnatherum hymenoides), and
needle-and-thread grass (Hesperostipa comata).
Very little surface water is present on the INL during the spring
and summer. The Big Lost River and Birch Creek drainages are both
diverted upstream for agricultural purposes and consequently little
if any stream water reaches the INL. During years of high flow
volume the Big Lost River can reach the INL and drains into an
ephemeral wetland known as the Lost River Sinks. The Lost River
Sinks wetland provides the only substantial water source for
waterfowl and shorebirds on the INL, however a number of man-made
waste treatment ponds near facilities also provide aquatic habitat
for migrating birds.
The Idaho Comprehensive Wildlife Conservation Strategy (CWCS)
recognizes wildlife species that are listed by either State or
Federal agencies and provides a comprehensive listing of the Idaho
Species of Greatest Conservation Need (SGCN) (Appendix B: Idaho
Department of Fish and Game 2005). The CWCS also identifies Idaho
Important Bird Areas (Appendix H: Idaho Department of Fish and Game
2005), and the INL has received such designation.
The BBS is a roadside count of all birds seen or heard along
predefined routes. Thirteen BBS routes (Figure 1)
were surveyed between May 22 and June 12, 2007, consisting of five
official USGS BBS remote routes in addition to eight facility routes
developed specifically for the INL. Each remote survey route is
24.5 miles (39.2 km) long with 50 systematically spaced sampling
locations located every 0.25 miles (0.4 km). The facility routes
vary in total length depending on the size of the facility, and
sampling locations are spaced approximately 0.2 miles (0.4 km)
The North American BBS protocols provided by the USGS Patuxent
Wildlife Research Center were followed during these surveys. At
each sampling location, a trained observer records every bird
species visually observed within a quarter mile radius or heard
(song) during a 3-minute time period. Any bird that was suspected
of being counted on the previous stop was not recorded a second time
at the next sequential stop. A number of additional data such as
temperature, wind speed, and sky condition are recorded at the
beginning and end of each survey route and each route is only
surveyed when weather conditions are appropriate (e.g., no heavy
rains or strong wind). BBS surveys begin a half-hour before sunrise
and can continue for up to 6 hours until the route is complete. The
total number of cars that pass during the 3-min sampling period are
recorded on all remote routes, and if background noise becomes loud
enough to interfere with audible detection it is also noted.
Bird Abundance Correlation
In previous INL BBS reports, environmental abiotic factors were
investigated in an attempt to explain the variation in observed bird
abundance. Belthoff et al. (1998) found a relationship between cool
and wet June weather and bird abundance for 1985-1991. Belthoff and
Ellsworth (1999) found that bird abundance was significantly
negatively correlated with mean June temperature, where higher bird
abundance corresponded to lower temperatures. A relationship between
bird abundance and June precipitation was noted, and although not
statistically significant, the removal of an outlier from 1995 would
have resulted in a significant p-value (Belthoff and Ellsworth
1999). Belthoff and Ellsworth (1999) used the Spearman rank
correlation coefficient to identify correlations with June
temperature and precipitation, and the same statistic was
recalculated this year to compare current relationships in the 2007
The Spearman rank correlation is a non-parametric test used to
investigate the relationship between variables (Spearman 1904).
Instead of using the raw abundance data, both variables are ranked
in increasing order and the assigned ranks are used in the
statistical analysis. The Spearman rank correlation coefficient (rs)
is calculated using the following equation, where (d) is the
difference between the ranks and (n) is the sample size.
In cases where two data values have a tied rank, a
different equation is used to account for the tied ranks (Thomas
1989). The first equation is calculated for both variables (x and y)
where (ti) is the number of tied values, and the second
equation calculates the Spearman Rank Correlation coefficient
corrected to rank ties (rs)c .
Mean June temperature and total June precipitation
data collected since 1985 at the Central Facilities Area (CFA) were
used to test bird abundance correlations. Statistical significance
was calculated using a two-tailed hypothesis with an alpha of 0.05.
The June precipitation data contained a tied ranking, and the
corrected equation described above was calculated for these data.
Community Diversity Indices
Diversity describes the number of interacting
organisms in an ecological system and is commonly defined by species
abundance and richness. A community with low species diversity may
be indicative of an unhealthy or improperly functioning community.
Higher species diversity is often interpreted as a stable,
functioning system and increasing diversity is the goal of many
Species diversity indices are a mathematical way to quantify
community composition. There is a number of diversity indices
commonly used in ecology and each has particular strengths depending
on the data and the questions. The simplest estimate of community
diversity is species richness, which represents the total number of
unique species present. Although species richness is a useful
measure of diversity it does not account for differences in
abundance between communities. For example, if there are many
species with a single individual observed, richness will be high but
may not be comparable to another community with the same number of
species and large abundances across all species. Diversity indices
that consider both species richness and species abundance may
provide a more useful measure of community diversity.
One of the most popular diversity indices used by biologists is the
Shannon diversity index (H) (Shannon 1948). Shannon’s
diversity index takes into account both species richness (S)
and relative abundance of each species present in the community.
Shannon’s diversity index is derived by first calculating the
proportion of species i relative to the total number of
species (pi), and then multiplied by the natural
logarithm of this proportion (lnpi). The resulting
product is then summed across species and multiplied by -1.
Shannon’s H can range from zero to about 4.6 with higher
values representing increasing diversity.
Another useful measure that can be derived is
Shannon’s Equitability (EH). Shannon’s
Equitability represents a measure of evenness which is how similar
species abundance is among the community. EH
ranges from 0-1 with one representing a completely even community
where all species abundances are equal.
H and EH were calculated for all BBS
routes, and compared to standard species richness information
reported in past reports. Each survey route was considered as a
representation of the local bird community, and community diversity
index values reflect BBS route diversity.