From June 1-24, 2004, 14 permanent routes located at the Idaho National Laboratory (INL) was
surveyed for breeding birds. A total of 6,479 individuals
representing 62 species of birds were recorded along the routes.
This was higher than the average of 4,719 birds/year recorded from
1985-2003. Although current trends show that the total number of
birds that breed on the INL are increasing with the greatest
increases in grassland birds such as Horned Lark and Western
Meadowlark, species of special concern show an overall decline since
1985. Species of special concern recorded in 2004 included
Long-billed Curlew (N = 2), Ferruginous Hawk (N = 19), Swainson’s
hawk (N = 8), Sage Grouse (N=4), and Loggerhead Shrike (N = 44).
Burrowing Owl (Athene cunicularia), a species of special
concern, has not been observed on a Breeding Bird Survey at the
INL since 2000.
Abundance
A total of 6,479 individual birds were recorded along the 14 survey
routes in 2004. This is the second highest year of bird abundance
since the surveys began in 1985 (no surveys were conducted in 1992
or 1993).
Total number of birds recorded by year (1985-2004) along 14
permanent routes at the INL.
Bird numbers increased slightly from 2003 which may be due to normal
rainfall conditions during May and June which has not occurred since
the drought began in 1999. Horned Larks and Meadow Larks were still
the dominant species on the INL and represented almost 50 percent
of all birds counted. These species appeared to be stabilizing since
their numbers increased exponentially in 2003 in response to more
available habitat created by the fires of 2000. The conversion of
sagebrush steppe vegetation communities to grassland, due to large
fires, has allowed these species, as well as other grassland species
(e.g. Vesper Sparrow, and Mourning Dove), to increase in abundance.
Overall, the five most numerous species in order of abundance were:
Horned Larks
Western Meadowlarks
Brewer's Sparrows
Franklin’s Gull
Sage Sparrows.
Sage Thrashers were removed from the top 5 in 2004
because of the large number of Franklin’s Gulls. More than 70
percent of all birds detected in 2004 were one of the above six
species, which have, in the past, usually been the most frequently
counted species on the INL.
Species Richness
In 2004, 62 species were detected during the surveys. Although there
were slightly fewer species observed than in 2003, it is above the
average of 57 ±
4 recorded from 1985-2003. Many similar species were recorded for
both remote routes (21
± 4) and
facility routes (22
± 2).
The fewest number of species (N=18) were observed along the Circular
Butte, Twin Butte and PBF routes, while Tractor Flat and NRF had the
greatest number of species (N=27).
Total number of species recorded by year (1985-2004) along 14
permanent survey routes at the Idaho National Laboratory.
Species of special concern
State and Federal species of special concern observed during the
2004 census included Long-billed Curlew (N = 2), Ferruginous Hawk (N
= 19), Swainson’s Hawk (N = 8), Loggerhead Shrike (N = 44), and
Greater Sage Grouse (N = 4). The Burrowing Owl has not been observed
in the INL BBS since 2000. The sagebrush steppe habitat on the
INL continues to support species of birds that are low or
declining in number throughout the remainder of the Intermountain
West.
Summary
A relatively high number of birds were counted along the BBS routes
at the INL in 2004. Even though Horned Lark numbers appear to be
stabilizing, record numbers of them continue to be observed,
boosting the overall total of birds considerably. Widespread and
increasing populations of Horned and Meadow Larks were not
unexpected considering that recent fires that have converted
extensive areas from sagebrush steppe to the grasslands that they
prefer. Most other bird species populations were comparable in
number to recent years including sagebrush obligates and species of
special concern.
These annual surveys provide valuable long-term data for land
managers to allow them to determine impacts of activities conducted
at the INL and surrounding areas on breeding bird populations.
Factors that may affect a population range from natural events such
as drought and wildfires to non-natural events such as the removal
of resources through development or chemical application. These data
also contributed to a nationwide database of bird population trends
that is used by state and federal agencies.
