Breeding Bird Survey Results within the Applegate AMA and Cascade Zone of the Rogue River National Forest

Background: The North American Breeding Bird Survey (BBS) is a continent-wide monitoring program for all breeding birds.  It officially began in 1966 and today has expanded to include over 4,000 routes across the continent.  These roadside surveys are conducted at the peak of the breeding season (normally in June) and begin ½ hour before official sunrise.  Each BBS route is 24.5 miles long and consists of 50 stops located at 0.5 mile intervals.  The observer records all birds seen or heard at each stop during a 3-minute period.  The primary objective of the BBS is estimating short and long term population changes for songbirds.  Population declines of neo-tropical migrant birds, birds which breed in North America and winter in the Caribbean and Central and South America, have been of concern in recent years.

There are two official BBS routes on the Rogue River National Forest that have been surveyed every year since 1992.  The Ruch route is located in the Applegate Adaptive Management Area (AMA) on the Applegate Ranger District within the South Pacific Rainforest province (i.e. northwestern California, western Oregon, and western Washington).  It begins approximately 3 miles north of the Oregon-California state-line and runs in a northeasterly direction.  The Whiskey Springs route is located on the Butte Falls Ranger District in the Cascade Mountain province.  This route begins approximately 34 miles north of the Oregon-California state-line and runs in a north-northeasterly direction.  Seven years of data from these two survey routes was analyzed.  Trends were determined based on the following criteria for a species: 1) must have been detected at least four of the seven years and 2) must exhibit a fairly consistent increasing or decreasing trend, otherwise it was considered stable.  Species detected less than four years or less than five total individuals, were considered to have indeterminable trends.  A comparison was made between results from both routes, as well as with statistically analyzed BBS results on population trends for various species.

Findings: Overall, species diversity was higher on the Ruch route than on Whiskey Springs route. Out of the 86 species detected on Ruch, 29 species (34 percent) appeared to be fairly stable or exhibit what may be normal fluctuations in numbers; 35 species (41 percent) were detected only occasionally or in too small of numbers to identify any possible trends; and 22 species (26 percent) appeared to show a definite decrease in numbers. Out of the 56 species detected on Whiskey Springs, 23 species (41 percent) appeared to be fairly stable; 21 species (38 percent) were detected only occasionally, and 12 species (21 percent) appeared to show a definite decrease in numbers.  No species on either route appeared to show a definite increase in numbers.

A higher percentage of species appeared to be decreasing on Ruch (26 percent) as compared to Whiskey Springs (21 percent).  Of the 26 percent on Ruch, 41 percent were neo-tropical migrants, 45 percent were short distance migrants, and 14 percent were permanent residents.  Of the 21 percent on Whiskey Springs, 42- percent were neo-tropical migrants, 25 percent were short distance migrants, and 33 percent were permanent residents.

Looking at the numbers of species decreasing by breeding habitat group on Ruch, 17 (77 percent) were woodland breeding species, 2 (9 percent) were successional-scrub breeders, and 3 (14 percen percent) were urban breeders.  On Whiskey Springs, 9 (75 percent) were woodland breeding, 2 (17 percent) were successional-scrub breeders, and 1 (8 percent) was an urban breeder.  Taking this one step further, I looked at the decreasing species by nest location.  Of the 22 decreasing species on Ruch, 20 (91 percent) were mid-story to canopy nesting species and only 2 (9 percent) were ground to low nesting species.  Of the 12 species on Whiskey Springs, 11 (92 percent) were mid-story to canopy nesting species, and only 1 (8 percent) was a ground to low nesting species.  On Ruch, 6 species (27 percent) were cavity nesters and on Whiskey Springs, 4 species (33 percent) were cavity nesters.  All other species were open cup nesters.

Of the 22 species that were decreasing on Ruch, 12 (55 percent) use mostly late-successional (>21" dbh <100percent canopy closure) conifer/mixed-conifer and/or conifer-hardwood/hardwood forest stands as primary habitat for breeding, 2 (9 percent) use closed sap-pole (1-21" dbh, >60percent canopy closure) to late-successional stands, 1 (5 percent) uses open sap-pale to late successional stands, 2 (9 percent) uses open sap-pole and late successional stands, and 5 (22percent) utilize open sap-pole (1-9" dbh <60percent canopy closure) and/or shrub communities as primary breeding habitat.  Of the 12 species that appeared to be decreasing on Whiskey Springs, 6 (50 percent) utilize late-successional conifer/mixed-conifer and/or conifer-hardwood/hardwood forest stands as primary habitat for breeding, 2 (17 percent) use closed sap-pole to late-successional stands, and 4 (33 percent) utilize open sap-pole stands and/or shrub communities as primary breeding habitat.  Six of these species (Hammond's flycatcher, Steller's jay, Red-breasted nuthatch, Chestnut-backed chickadee, Nashville warbler, and Pine Siskin) appeared to be decreasing on both routes (Table 1).  Four of these six species use late-successional coniferous/mixed coniferous forest as primary breeding habitat; one (Pine siskin) uses closed sap-pole to late-successional stands as primary breeding habitat; and one (Nashville warbler) uses open sap-pole and/or shrub communities as primary breeding habitat .

A comparison of the 22 possible decreasing trends for the Ruch route with BBS trends for the South Pacific Rainforest (SPR), Oregon, and California, showed (where information was available) that decreasing trends for 12 species directly correlated with BBS trends.  Three species (Red-shafted flicker, Red-breasted nuthatch, and American robin) showed an increasing trend in SPR, two species (Chestnut-backed chickadee, and Warbling vireo) showed an increasing trend in Oregon, two species (Tree swallow and Purple finch) showed increasing trends in California, one species (Hermit warbler) showed an increasing trend in both SPR and Oregon, and two species (House wren and Brown-headed cowbird showed increasing trends in Oregon and California, but otherwise correlated with BBS trends.  Two species (Steller's jay and Black-headed grosbeak) inversely coincided with all three BBS trends.  Although my analysis shows the Brown-headed cowbird has a decreasing trend on the Ruch route. as well as decreasing BBS trends for the SPR, the BBS does not recommend any management to reverse this trend.

A comparison of the 12 possible decreasing trends for the Whiskey Springs route with the BBS trends for the Cascade Mountains, Oregon, and California showed (where information was available) that decreasing trends for 4 species (Mountain chickadee, Chipping sparrow, Pine Siskin, and Evening grosbeak) directly correlated with BBS trends.  Three species (Hammond's flycatcher, Red-breasted nuthatch, and Nashville warbler) showed increasing trends in the Cascades, and one species (Chestnut-backed chickadee) showed an increasing trend in the Cascades and Oregon, but otherwise correlated with BBS trends.  Four species (Steller's jay, Common raven, House wren, and Cassin's vireo) inversely correlated with BBS trends.

In summary, 55 percent (12 species) and 33 percent (4 species) of route level trends on Ruch and Whiskey Springs directly correlated with BBS trends in all three provinces/states, whereas 9 percent (2 species) and 33 percent 
(4 species) inversely correlated in all three areas.  The remaining species directly correlated in some provinces/states but inversely correlated in others.

Applications: Of the 28 decreasing species on both the Ruch and Whiskey Springs routes, 77 percent and 75 percent respectively, were woodland breeders; 91 percent and 92 percent respectively, primarily nest in the middle to upper canopy; and 55 percent and 50 percent respectively, use late-successional conifer/mixed-conifer and/or conifer-hardwood/hardwood forest stands as primary breeding habitat.  Seventy eight percent of the decreasing species on the Ruch route and 67 percent of the decreasing species on the Whiskey Springs route utilize late-successional forest stands as primary breeding habitat at least to some degree, if not exclusively.  Greater than 40 percent of the decreasing species on both routes were neo-tropical migrants.  In addition, on Ruch, 45 percent of the decreasing species were short distance migrants.

In conclusion, most of the species that appeared to be decreasing on both the Ruch and Whiskey Springs routes were woodland breeding neo-tropical and short distance migrants which use the middle to upper canopy of late-successional stands as primary breeding habitat.  Since the Northwest Forest Plan went into effect in 1994, the harvesting of late-successional habitat has been greatly reduced on federal lands.  Past timber harvest activities may continue have an effect on late-successional species, however, current management guidelines on federal lands which retain large blocks of late-successional habitat should help to reduce these effects in the future.

Follow up: Breeding Bird Surveys on these routes will continue as long as personnel and budget allows.  Most likely seven years is not sufficient to determine long term declines for these species therefore more years of data are needed.  In addition, my results are based on single route-level analyses so most likely are not representative of actual trends, hence the comparison with BBS trends which would give us more insight on the actual trends for these species.

References:

Sauer, J.R., J.E. Hines, G. Gough, I. Thomas, and B.G. Peterjohn.  1997.  The North American Breeding Bird Survey Results and Analysis.  Version 96.4.  Patuxent Wildlife Research Center, Laurel, MD

USDA Forest Service.  Pacific Northwest Region.  1985.  Management of Wildlife and Fish Habitats in Forests of Western Oregon and Washington.  Part 2- Appendices..

Submitted by: Gail F. Rible, Wildlife Biologist; Applegate Ranger District; 541-899-1812

Breeding Habitat Group                Migration Form Group                                       Trends
WB- Woodland species                N- Neotropical migrant species                          s- =significant decline
SS- Succesional-scrub species      SDM-Short distance migrant species                  ns=nonsignificant decline
UR-Urban species                        R-Permanent resident species                             s+=significant increase
                                                                                                                              ns+=nonsignificant increase
                                                                                                                              -=decreasing
                                                                                                                              ind=indeterminable
                                                                                                                              blank=no BBS

Nest Type Group                                                   Nest Location Group   
C-Cavity nester                                                      G-Ground to low nesting
O-Open cup nester                                                M-Mid-story to canopy nesting