Annual breeding bird surveys have been conducted on
the Idaho National Laboratory (INL) since 1985 to monitor changes in
bird populations. Surveys were conducted in in 2006 during May and
June. A total of 5,974 individuals representing 66 species of birds
were recorded along 13 permanent routes. Horned lark (n=1616), western
meadowlark (n=1055), Brewer’s sparrow (n=794), sage thrasher (n=458),
sage sparrow (n=333) and mourning dove (n=333) are the top six most
abundant species on the INL. Nine species indicated as Species of
Greatest Conservation Need recorded include Brewer’s sparrow (n=794),
sage grouse (n=46), Franklin’s gull (n=41), ferruginous hawk (n=10),
western burrowing owl (n=5), long-billed curlew (n=5), short-eared owl
(n=4), Wilson’s phalarope (n=4), and Merlin (n=1). This is only the
second year that a Merlin was observed during the annual Breeding Bird
Survey since the survey began in 1985.
The Breeding Bird Survey (BBS) is a large-scale survey
of North American birds. It is a roadside route survey of avifauna
designed to monitor abundance and distribution of birds primarily
covering the continental United States and southern Canada, although
survey routes have recently been initiated in Alaska and northern
Mexico (Sauer et al. 2003). The BBS was started in the eastern U.S. in
1966 with over 3,500 routes currently surveyed each June by
experienced birders (USGS 2001a).
The primary objective of the BBS is the estimation of
population change for songbirds. However, the data have many potential
uses, and investigators have addressed a variety of research and
management objectives.
The Idaho National Laboratory (INL), located in
southeastern Idaho, is comprised of large expanses of relatively
undisturbed shrub-steppe and grassland habitat. This area was
designated as a National Environmental Research Park in 1975 and
serves as an outdoor laboratory to assess environmental impacts of
nuclear energy development technologies. Since 1985, official BBS and
unofficial facility routes have been surveyed at the INL. These
surveys yield useful information about population dynamics, effects of
weather and fire on avian abundance, affects of INL facilities on
avifauna, and the breeding status of a number of bird species of
concern, including sagebrush obligate species and other species
exhibiting declines throughout their range (e.g., see Belthoff and
Ellsworth 1996, 1999 and 2000, Belthoff et al. 1998, and Ellsworth
2001).
This report summarizes results of surveys conducted in
2006 at the INL and compares findings to BBS surveys from previous
years.
These annual surveys provide valuable long-term data
for land managers and allow them to determine impacts of activities
conducted at the INL and surrounding areas on breeding bird
populations. These data also contribute to a nationwide database of
bird population trends that is used by state and federal agencies.
The 894-mi² (2,315-km²) INL is located approximately
30 mi (48 km) west of Idaho Falls on the upper Snake River Plain in
southeastern Idaho, and occupies portions of Bingham, Bonneville,
Butte, Clark, and Jefferson counties. The area is a semi-arid, cold
desert with an elevation of approximately 4921 ft (1500 m) above sea
level. Anderson et al. (1996) detailed the climate, geology, and
vegetation of the INL. Briefly, vegetation in the study area is
typical of shrub-steppe ecosystems and is dominated by woody,
mid-height shrubs and perennial bunchgrasses. Big sagebrush (Artemisia
tridentata) dominates much of the vegetation on the site, but
other primary shrubs include green rabbitbrush (Chrysothamnus
viscidiflorus), shadscale (Atriplex
confertifolia), and winterfat (Krascheninnikovia lanata).
Native grasses that are dominant throughout the site are bottlebrush
squirreltail (Elymus elymoides), thickspike wheatgrass (Elymus
lanceolatus), needle-and-thread grass (Hesperostipa comata),
Indian ricegrass (Achnatherum hymenoides), and bluebunch
wheatgrass (Pseudoroegneria spicata). Basalt lava flows
dominate the geology of the region, and the topography is flat to
gently rolling, with the exception of East and Middle Buttes, which
protrude from the southern portion of the area. The southern
extensions of two of the largest mountain ranges in Idaho (Lost River
and Lemhi Mountains) rise above the INL site and Snake River Plain to
the north and west. The area experiences hot, dry summers and cold
winters (Short 1986). Annual precipitation averages approximately 8
in. (20 cm), and most of this occurs during the spring. Surface water
in the summer is limited to residual flows of the Big Lost River and
Birch Creek, each of which are diverted upstream of the site for
agriculture and flood prevention. During the spring, the Big Lost
River may flow into an ephemeral wetland known as the Lost River
Sinks, which can provide nesting and migratory stopover habitat for
waterfowl and shorebirds. Several human-made wastewater treatment
ponds are located near research facilities which attract birds that
prefer aquatic habitats.
Thirteen Breeding Bird Survey routes were surveyed
once each from May 18 – June 16, 2006 (Figure 1). Five remote routes are standard 25-mi (40-km) BBS routes, data
from which are reported to the USGS Biological Resources Division
annually. These routes traverse the remote areas of the INL and
include major habitat types throughout the site. Eight facility routes
are located in and around major INL facility complexes.
The North American Breeding Bird Survey protocol provided by USGS
Patuxent Wildlife Research Center (USGS 2001b), was followed during
these surveys. On remote routes, we located 50 stops at approximately
0.5 mile (0.8 km) intervals and counted all individual birds (except
dependent young) of all species seen or heard during a 3-minute period
within 0.25 mile (0.4 km) of the stop. Facility routes consist of
18–60 stop locations at approximately 0.2 mile (0.32 km) intervals and
individual birds were recorded if they were within 0.1-mile (0.16 km)
from the observer (i.e., half the distance between stops). Individuals
known or strongly suspected to have been counted at a previous stop
were not recounted. Surveys began approximately ½ hour before official
sunrise as given by the Astronomical Applications Department, U.S.
Naval Observatory (2005). A certified BBS observer relayed counts
verbally from outside the vehicle to an assistant who recorded the
information on an official data sheet. Each route took approximately
1- 6 hours to complete.
Temperature, wind speed, and cloud cover were recorded
at the start and end of each survey route. Surveys were conducted only
under satisfactory weather conditions including good visibility,
little or no precipitation, and light winds in order to be comparable
to previous years. Survey dates for each route are in
Appendix B.
Single Factor Analysis of Variance was used to test
the differences among years for all routes, and facility and remote
routes for both abundance and species diversity. Even though
comparisons between remote routes were conducted comparisons between
facility routes, and facility and remote routes are problematic since
the areas surveyed are not consistent. A level of 0.05 was used to
determine significance.
Appendix B contains summaries of the data and results from
the analysis of variance. Trends for selected species were calculated
by using least squares. Trend data is used to display what populations
of selected species have been doing over time and their responses to
habitat change.
