Breeding Bird Survey Results 2002

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.


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