Abundance
The 2002 Breeding Bird survey took place June 10 - June 23.
A total of
5,808 individual birds was recorded along the 13 survey routes.This is the fourth highest total recorded (see Figure 1)
and well above the 1985-2001 average of 4,590.4 birds/year
(no surveys were conducted in 1992 or 1993).The total number of birds counted during surveys is now
74,390 and the average per year is 4,649.4 (1985-2002).
2002
marked a reversal in a 3-year downward trend in the number of
birds counted at the site.This is notable, in part, because the spring of 2002 was
dry and fewer birds are usually counted when there is little
spring moisture, and the highest numbers of birds are typically
counted in years with greater spring moisture..The high numbers of birds counted in 2002, however, does
not necessarily reflect large numbers of birds counted among all
taxa.Several species were at or below long-term averages and the
relative abundance of a number of birds species continued to
decline in the last 3 years.Instead, the total count was inflated by record numbers of
Horned Lark and Franklin’s Gull.The recent increase is not surprising as Horned Lark are a
dominant component of grasslands on the INL, and fires in recent
years (particularly 2000) have converted large areas of sagebrush
to grasslands.Likely, Horned Lark will continue to dominate the avifauna
of the INL, and other species that nest in grasslands and low
shrubs should increase in number as well (i.e., Grasshopper Sparrow
and Vesper Sparrow).
At the same time, however, fire has reduced sagebrush
habitat on the INL, which is the primary nesting and foraging
habitat for many bird species, including the sagebrush obligates
(Brewer’s Sparrow, Sage Sparrow, Sage Thrasher).Indeed, a recent downward trend in the number of sagebrush
obligate species counted is consistent with the notion that
sagebrush habitat is being lost and may be negatively effecting
these populations of birds.
Waterfowl counts at the INL were also low in 2002, which is characteristic
of dry springs when the Lost River and associated sinks are dried
up by the time surveys are performed in June.
Species
Richness In
2002, the total of 60 species detected during surveys was above
the average of 55.5 ±
7.5 recorded from 1985-2001.One new species for the BBS surveys, the Black-necked
Stilt, was observed at an Argonne facility pond. The total
number of species detected along the routes (1985-2002) is 113.
Overall, the five most numerous
species in order of abundance were:
Horned Larks (Eremophilia
alpestris)
Western Meadowlarks (Sturnella
neglecta)
Franklin Gulls
Brewer's Sparrows (Spizella
breweri)
Sage Thrashers (Oreoscoptes
montanus)
The inclusion of Franklin’s Gulls in this group is unusual,
as they are not typically one of the most common species and
are absent in most years on the INL
Comparisons
with Long-term Averages
As in recent years (1996-2001), none of the species
observed in 2002 were 2.5 or more standard deviations below
long-term (1985 – 2001) average abundance, although several
species recorded in previous years were not observed in 2002.
Several species recorded in
six or more previous years were
not observed in 2002.
Willet
Burrowing Owl
Mountain Bluebird
Lark Bunting
Lazuli Bunting
House Sparrow
Prairie Falcon
Golden Eagle
Species of special concern
recorded in 2002 included:
Long-billed Curlews (Numenius
americanus) N=1
Ferriginous Hawks (Buteo
regalis) N=14
Swainson's Hawks (Buteo
swainsoni) N=2
Loggerhead Shrikes (Lanius
ludovicianus) N=22
The INL continues to support
species of birds that are low or declining in number
throughout the Intermountain West.
