Breeding Birds in the IBA

We wanted to know how the breeding bird populations were faring in the Clark Fork River‐Grass Valley Important Bird Area (IBA) in order to know how well the IBA was protecting important bird species. To find this out we compared breeding bird survey data gathered by Chapter volunteers in 2003‐04 with data taken in 2009‐10. We were particularly interested in breeding populations of species of conservation concern. The table below summarizes the number of breeding pairs for species of conservation concern that were sampled during both time periods.

More of the IBA was sampled in 2009‐10 than the earlier dates so some increase in breeding pairs might be expected. Some variability in breeding pairs was expected due to normal fluctuations in bird activity and the variability inherent in the sampling process. With this in mind, we found that most of the species maintained stable breeding populations. The Lewis’s Woodpecker, a keystone species that gives the IBA a rating of Continental significance, did very well. We are concerned about the apparent decline of the Red‐eyed Vireo, a species that seeks cottonwood and aspen riparian areas. We are also puzzled by indications of decline in the Hooded Merganser and possibly Red‐napped Sapsucker. Overall however, we believe the IBA is functioning well and helping to protect important bird species.

by Jim Brown

Species 2003 2004 2009‐10
Hooded Merganser 12 5 3
Osprey 15 9 17
Bald Eagle 4 6 6
Red‐tailed Hawk 7 5 7
Peregrine Falcon 1 1 1
Calliope Hummingbird 14 9 17
Lewis’s Woodpecker 41 41 57
Red‐naped Sapsucker 24 30 22
Pileated Woodpecker 12 8 7
Willow Flycatcher 44 30 44
Veery 2 1 0
Red‐eyed Vireo 16 21 3
Warbling Vireo 17 11 25
Lazuli Bunting 0 14 16
Bobolink 3 7 4
Clay‐colored Sparrow 8 6 9

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