Breeding Bird Survey Results 2004

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.

 

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