Abundance
The 2001 Breeding Bird survey took place June 8 - June
21. A
total of 4,318 individual birds representing 51 species of
birds was recorded along the 13 permanent routes on the INL. This
is slightly below the average of 4,590.4 birds per year recorded
from 1985-2000, and the lowest recorded since 1991. In
part, low number of birds counted at the INL in 2001 may be
related to below average precipitation and above average
temperatures. Dry and warm springs are correlated with
lower bird counts on the INL, and in 2001 several species of
birds dependent on surface water were absent or infrequently
counted.
Bird counts for
sagebrush obligate species, such as Sage Sparrows (Amphispiza
belli), Brewer's Sparrows (Spizella breweri), and Sage
Thrashers (Oreoscoptes montanus) were lower than in recent years,
perhaps as a result of fires on the INL in the past two
years, which have reduced the amount of shrub cover along
three routes (Big Lost River, Tractor Flats, and TRA).
No surveys
were conducted in 1992 or 1993.
Species
Richness In
2001, the total of 51 species detected during surveys was
slightly below the average of 55.8 ± 7.6 recorded from
1985-2000. No new species were observed on BBS survey
route in 2001, and the total number of species detected along
the routes remains at 112.
Overall, the five most numerous
species in order of abundance were:
Horned Larks (Eremophilia
alpestris)
Western Meadowlarks (Sturnella
neglecta)
Brewer's Sparrows (Spizella
breweri)
Sage Thrashers (Oreoscoptes
montanus)
Sage Sparrows (Amphispiza
belli).
These five species together
comprised 70.9% of the birds detected. Similarly, these
species accounted for 71.4% of all birds observed from
1985-2000. Although there have been minor shifts in the
order over the years, it is clear that these five species are
dominant components of the ecosystems at INL.
Comparisons
with Long-term Averages
No species were recorded at
significantly greater numbers than in previous years (i.e.,
greater than 2.5 standard deviations above their 1985-2000
averages). However, large flocks of Franklin's Gulls (Larus
pipixcan) were observed at the site for the first time since
1989
, as they
foraged on semi-periodical cicadas that seem to hatch only
once every 12 years..
Several species recorded in previous years were
not observed in 2001.
