The Alaska Bird Observatory (ABO) has operated a large standardized mist-netting station at Creamer’s Field Migratory Waterfowl Refuge in Fairbanks, Alaska from 1992-2000. The objectives of the netting program are to capture and band migrating passerines to examine: 1) population dynamics; 2) the phenology of migration; 3) timing of life history events (e.g. migration, reproduction, molt, juvenal dispersal, and seasonal differences in body condition); 4) habitat use; and 5) to provide public education programs relating to avian ecology and conservation.

Approximately 150 migration-monitoring stations are located throughout North America. Creamer’s Field Migration Station (CFMS) is the northernmost station in the Western Hemisphere. The location of this study site provides crucial information for studying population trends in Nearctic-Neotropic migrants. The migration station has also become a popular destination for local school groups, naturalists, bird enthusiasts, and international visitors.

Data provided from CFMS support the goals and objectives of the Alaska Department of Fish and Game and Partners in Flight (PIF). PIF is a comprehensive Neotropical migratory bird conservation program of applied management, monitoring, and research implemented cooperatively by state and federal governments, industry, conservation organizations, and academia from North, South, and Central America.

METHODS
Field methods have remained relatively constant during nine years of migration banding at CFMS. Nets were opened at sunrise and closed seven hours later, or as late as 14:00 h, between 15 July and 30 September (weather permitting). For a detailed description of the methodology see Pogson et al. (1996).

Relative abundance
First-time captures of individuals were used in the analysis of abundance (newly banded birds, returns, foreign recoveries, and unbanded dead birds). Birds banded in spring or summer and recaptured in fall were not included, as they were assumed to be local breeders. Captures prior to 25 July were excluded, as they were likely breeding birds or local dispersing juveniles (based on molt and plumage), rather than migrants.

Daily capture rates (birds/1000 net hours) were calculated for each species. The annual population index was calculated as the geometric mean (arithmetic mean of the transformed counts, back transformed) of all daily migration counts for 19 abundant species (more than 10 individuals captured each fall). A constant (one) was added to each daily capture rate to compensate for counts of zero. Geometric mean (compared with arithmetic mean) is relatively insensitive to occasional unusually high counts while still reflecting small increases or decreases that are consistently present in daily counts across the entire migration season (Dunn and Hussel 1995).

Internships
Four college students and recent graduates received bird-banding training and experience. Each intern conducted an independent study to gain experience designing research questions and conducting analysis of migration data. The following intern projects were completed during 2000: habitat use of migrants during migration, causes of mortalities at CFMS, and assessment of sexing criteria for Orange-crowned Warblers.

Habitat Use by Migrants
Habitat characteristics surrounding the 30 mist nets at CFMS were measured in 2000. Measurements included visual estimates of flora present, height, and percent cover at tree canopy, shrub, and ground level. Habitat around each net was also described according to the classification system of Viereck et al. (1992) and digital photos were taken at each net. Capture data for fall migration 1997-1999 was used to evaluate habitat use by migrants. Recaptures were excluded from these analyses, as were species with fewer than 30 individuals captured per year.

Assessment of Sexing Criteria for Orange-crowned Warblers
We evaluated sexing criteria for Orange-crowned Warblers proposed by Pyle (1997). We examined wing, tail, and crown length of known-sex individuals (based on brood patch or cloacal protruberance) to determine whether these characteristics could be used to accurately determine the sex of this species in autumn.

Mortality
Causes of mortalities from the netting program were examined to develop recommendations for minimizing accidental deaths.

RESULTS

Summary 2000
We banded 4,702 birds of 31 species during the fall migration of 2000 (Table 1). Nets were operated for approximately 12,264 net hours (one net open for one hour). As in previous years, the most abundant species captured were Myrtle’s Warblers, Orange-crowned Warblers, American Tree Sparrows, and Slate-colored Juncos. These species comprised 78% of all birds banded. Although these four species were relatively abundant during 2000, population indices of seven species were at a nine-year low: Alder Flycatcher, Gray-cheeked Thrush, Swainson’s Thrush, American Robin, Blackpoll Warbler, Savannah Sparrow, and Fox Sparrow (Table 2). Notable captures include a Yellow-bellied Flycatcher and a Brown Creeper, the latter being a first record for CFMS.

Table 1. Number of birds banded at Creamer’s Field Migration Station during fall migration, Fairbanks AK: 1992-2000
Species	1992	1993	1994	1995	1996	1997	1998	1999	2000	Total
Northern Harrier	0	0	0	0	1	0	1	0	0	2
Sharp-shinned Hawk	3	2	1	3	8	3	14	6	2	42
American Kestrel	0	0	0	0	0	1	0	0	0	1
Merlin	0	0	0	0	0	0	2	0	0	2
Lesser Yellowlegs	0	0	0	0	1	0	0	0	0	1
Common Snipe	0	0	0	0	0	0	2	0	0	2
Downy Woodpecker	1	0	3	2	1	1	1	2	0	11
Hairy Woodpecker	0	0	0	1	3	1	1	2	0	8
Three-toed Woodpecker	0	3	1	0	0	0	0	2	0	6
Black-backed Woodpecker	0	0	0	1	0	0	0	0	0	1
Northern Flicker	0	0	0	0	2	2	0	1	0	5
Western Wood-Pewee	1	0	0	1	0	3	0	0	0	5
Yellow-bellied Flycatcher	0	0	0	0	0	1	1	0	1	3
Alder Flycatcher	36	75	62	64	68	124	57	45	40	571
Hammond's Flycatcher	9	13	40	49	86	71	34	30	38	370
Tree Swallow	0	0	0	0	1	0	0	0	0	1
Cliff Swallow	0	0	0	0	0	1	0	0	0	1
Gray Jay	0	1	0	1	1	0	0	0	0	3
Black-capped Chickadee	36	24	27	62	46	32	44	42	89	402
Boreal Chickadee	1	10	5	6	11	6	14	0	8	61
Brown Creeper	0	0	0	0	0	0	0	0	1	1
Red-breasted Nuthatch	0	0	1	2	1	0	0	0	4	4
Arctic Warbler	0	0	4	1	1	5	3	4	0	18
Golden-crowned Kinglet	0	0	0	1	0	0	1	0	0	2
Ruby-crowned Kinglet	55	89	127	123	233	196	139	62	112	1,136
Gray-cheeked Thrush	39	25	28	50	16	40	40	49	17	304
Swainson's Thrush	66	91	102	176	89	185	107	128	29	973
Hermit Thrush	6	5	7	15	20	18	24	19	23	137
American Robin	170	20	37	34	36	37	23	33	14	404
Varied Thrush	25	3	3	1	12	6	6	3	5	64
American Pipit	2	0	0	0	0	0	0	0	0	2
Bohemian Waxwing	5	0	0	0	0	0	1	0	0	6
Northern Shrike	0	1	1	1	2	0	3	4	1	13
Orange-crowned Warbler	458	233	597	865	456	637	918	672	468	5,304
Yellow Warbler	134	59	89	196	114	186	84	194	119	1,175
Yellow-rumped Warbler	835	56	1001	588	1164	1232	1351	687	1,764	8,678
Townsend's Warbler	3	2	2	3	5	10	5	3	5	38
Blackpoll Warbler	86	21	49	51	49	102	44	170	30	602
Northern Waterthrush	43	30	17	28	33	49	40	49	29	318
Wilson's Warbler	133	108	116	169	75	186	153	127	76	1,143
American Tree Sparrow	112	395	343	660	274	757	1203	727	812	5,283
Savannah Sparrow	47	72	28	174	83	103	95	201	58	861
Fox Sparrow	16	30	42	32	37	66	70	70	20	383
Lincoln's Sparrow	179	149	177	362	233	246	284	134	200	1,955
Golden-crowned Sparrow	2	0	0	0	2	0	2	4	1	11
White-crowned Sparrow	43	41	60	43	120	69	97	32	63	568
Dark-eyed Junco	144	162	535	413	578	456	816	414	658	4,176
Lapland Longspur	0	0	0	0	0	0	0	0	0	0
Rusty Blackbird	1	1	0	0	50	1	4	1	11	69
White-winged Crossbill	0	0	0	0	0	0	0	0	0	0
Common Redpoll	2	0	17	164	47	5	69	28	7	339
Hoary Redpoll	0	0	0	5	0	0	0	0	0	5
Total Number Banded	2,684	1,721	3,523	4,346	3,958	4,839	5,753	3,945	4,701	35,470
Net Hours	5,890	13,712	13,935	14,156	14,985	14,617	12,091	12,111		114,002

Table 2. Population indices using geometric mean of daily fall migration counts (birds/1000nh) for 19 abundant species (n>10 individuals each year) at CFMS from 1992-2000.
Species	1992	1993	1994	1995	1996	1997	1998	1999	2000
Alder Flycatcher	2.60	3.26	3.03	4.92	3.39	4.27	2.50	2.13	1.72
Hammond's Flycatcher	1.42	1.47	2.00	2.21	3.35	2.54	1.96	1.90	1.59
Black-capped Chickadee	2.18	1.58	1.53	3.39	1.79	1.84	8.21	2.37	2.86
Ruby-crowned Kinglet	3.10	3.61	5.46	4.62	6.42	5.53	5.74	2.47	4.18
Gray-cheeked Thrush	3.17	1.85	1.94	2.88	1.59	2.26	3.68	1.80	1.51
Swainson's Thrush	4.76	4.36	3.68	6.31	4.04	5.88	5.87	4.25	2.10
American Robin	2.48	1.48	2.04	1.91	1.98	1.96	1.77	1.87	1.44
Orange-crowned Warbler	27.78	8.30	19.68	26.88	17.89	24.81	25.78	15.95	14.88
Yellow Warbler	7.12	3.34	3.39	7.42	3.89	5.69	3.02	5.68	3.53
Myrtle Warbler	35.92	2.15	23.52	15.63	21.93	30.42	39.83	13.92	33.71
Blackpoll Warbler	4.02	1.69	2.50	3.01	2.69	3.18	2.76	3.44	1.80
Northern Waterthrush	5.15	2.53	1.66	2.37	2.10	2.83	2.25	2.70	2.16
Wilson's Warbler	6.61	4.07	4.38	7.22	3.53	3.89	4.73	3.08	3.14
American Tree Sparrow	6.34	13.38	11.64	28.78	12.44	24.66	14.68	10.19	6.70
Savannah Sparrow	3.19	3.41	1.73	6.48	3.20	3.70	5.22	5.80	2.91
Fox Sparrow	1.98	1.88	2.21	2.03	2.42	2.79	2.91	2.59	1.56
Lincoln's Sparrow	18.06	5.47	6.31	13.47	8.29	10.65	15.31	5.33	6.98
Gambel's White-crowned Sparrow	3.37	2.24	3.29	2.38	3.91	2.40	2.02	2.00	3.29
Slate-colored Junco	10.46	7.28	25.16	17.26	23.21	21.04	54.98	15.01	17.25

Habitats sampled through mist netting at CFMS—Eleven habitat types were identified around CFMS mist nets: closed broadleaf forest, open broadleaf forest, broadleaf woodland, closed mixed forest, open mixed forest, open dwarf tree scrub, dwarf tree scrub woodland, open tall scrub, mesic forb herbaceous, and mesic graminoid herbaceous.

Closed broadleaf forest (nets 1, 7, 25, 28, and the east side of 26 and 27)—Tree species present were Populus tremuloides, Populus balsamifera, Betula papyrifera, and a few Picea glauca seedlings. Average height of the tree canopy was 5-10m, with more than 60% cover. Dominant shrub was Salix spp. with average height of 1.5-5m. Rosa acicularis was present at some nets, as were a few non-native species (Prunus spp. and lilacs). Shrub cover was between 25-75%. Ground cover was sparse, composed of a few herbs and horsetails (Equisetum spp.).

Open broadleaf forest (nets 2, 3, 4, 13, 17, 19, 20, 30)—Species composition and height matched the closed broadleaf forest classification, but tree canopy cover in open broadleaf was less (25-59%).

Broadleaf woodland (net 15 and the west side of 24)—Betula papyrifera, with an average height of 5-10m, and Populus balsamifera, with an average height greater than 10m, were present. Canopy cover was 10-25%. Shrubs present were Salix spp. and dwarf Betula spp., with a height of 1.5-5m and cover of 25-75%.

Closed mixed forest (net 5)—Habitat surrounding the net was on the cusp of open/closed. Tree species present were Populus tremuloides and Picea glauca. Average height of the trees was 5-10m, and cover was about 60%. The dominant shrub species was Rosa acicularis, less than 1.5m tall and with 25-75% cover. Ground cover was predominantly herbs.

Open mixed forest (nets 6 and 18)—The same species as in closed mixed forest were present, though the tree canopy at net 6 reached heights greater than 10m. Tree canopy cover was between 25 and 59%.

Open-dwarf tree-scrub (net 11)—There were no trees taller than 5m present at this net. Salix spp., 1.5-5m in height, was the dominant shrub, with cover of 25-75%. Ground vegetation consisted of graminoids.

Dwarf tree scrub woodland (net 12 and the west side of net 26)—This habitat was more open than open dwarf tree scrub. Shrub cover was less than 25% in this habitat.

Closed tall scrub (east side of net 24)—Salix spp. between 1.5 and 3m tall with cover greater than 75% formed a dense thicket.

Open tall scrub (nets 16, 21, 22, 23, and 29).—A single tree species, Betula papyrifera was present in low numbers, less than 10% cover. The dominant shrub was Salix spp. with a height of 1.5-5m and 25-75% cover. At net 29, Prunus spp. was present rather than Salix spp.

Mesic forb herbaceous (west side of net 27).—Populus balsamifera seedlings were present, but the vegetation was primarily herbaceous forbs.

Mesic graminoid herbaceous (nets 8, 9, 10, and 14).—A few Betula papyrifera were present (less than 10%). Salix spp. was also present, with less than 25% cover. Vegetation was dominated by graminoids.

Three of the 30 nets at CFMS were excluded from the analysis because the habitat surrounding those nets did not fall clearly into a single classification. Over three years in 27 nets, 19 species with adequate sample sizes (13,551 individuals) were captured in nine different habitat types.

Habitat Use by Migrants
Alder Flycatcher(n=236)—Most Alder Flycatchers were captured in scrub or mesic graminoid herbaceous habitat. Eighteen percent were captured in net 11, open dwarf tree scrub. Additionally, 16% were captured in net 9, and 14% in net 10, both mesic graminoid herbaceous. Relatively few were captured in broadleaf forest.

Hammond’s Flycatcher (n=134)—Most Hammond’s Flycatchers were captured in net 25, closed broadleaf forest. Captures in other forest nets were low—less than 7 individuals in any other forest net, zero in nets 17 and 18. Net 23, open tall scrub, captured 14% of this species.

Black-Capped Chickadee (n=116)—This species was captured in all habitat types, although the greatest proportion of individuals (17%) was captured in net 25, a closed broadleaf forest.

Ruby-crowned Kinglet (n=399)—Thirteen percent of Ruby-crowned Kinglets were captured in net 23, open tall scrub, and 11% were captured in net 25, closed broadleaf forest.

Gray-cheeked Thrush (n=125)—Most Gray-cheeked Thrush were captured in closed broadleaf forest, including net 25 (18%) and net 28 (15%).

Swainson’s Thrush (n=420)—Thirteen percent were captured in net 28, and 11% in net 25, both closed broadleaf forest. No individuals were captured in dwarf tree scrub woodland.

Orange-crowned Warbler (n=2,269)—This species was captured in all habitat types and all nets. Fifteen percent were captured in net 23, open tall scrub, and 11% were captured in net 12, dwarf tree scrub woodland.

Yellow Warbler (n=470)—This species was captured in all habitat types. Seventeen percent were captured in net 9, and 11% were captured in net 10, both mesic graminoid herbaceous. Twelve percent were captured in net 23, open tall scrub. Relatively few individuals were captured in other nets.

Myrtle Warbler (n=3,313)—Twenty-two percent of Myrtle Warblers were captured in net 23, open tall scrub, although this species was captured in all habitats.

Blackpoll Warbler (n=327)—Many Blackpoll Warblers (16%) were captured in net 23, open tall scrub. No individuals were captured in closed mixed forest, nets 4 and 30 (open broadleaf forest), and net 18 (open mixed forest).

Northern Waterthrush (n=139)—Captures of this species were fairly evenly distributed among all nets. Most birds were captured in net 10, mesic graminoid herbaceous, 8%.

Wilson’s Warbler(n=405)—Fifteen percent of individuals were captured in net 23, open tall scrub. Relatively few were caught in forest habitats, with the exception of nets 25 and 13.

American Tree Sparrow (n=2,736)—This species was captured most frequently in open dwarf tree scrub, dwarf tree scrub woodland, and mesic graminoid herbaceous habitats. Fifteen percent were captured in net 9, mesic graminoid herbaceous habitat. Fourteen percent were captured in net 12, dwarf tree scrub woodland.

Fox Sparrow (n=206)—Eighteen percent of Fox Sparrows were captured in net 25, surrounded by closed broadleaf forest.

Gambel’s White-crowned Sparrow (n=206)—A large proportion of White-crowed Sparrows (13%) was captured in net 9, mesic graminoid herbaceous. All nets in mesic graminoid herbaceous habitat caught relatively high numbers of this species. Many individuals were also captured in open tall scrub.

Lincoln’s Sparrow (n=679)—Most Lincoln’s Sparrows (22%) were captured in net 23, open tall scrub. Fifteen percent were captured in net 8, mesic graminoid herbaceous. This species was primarily captured in scrub or herbaceous habitats.

Savannah Sparrow (n=401)—Twenty-one percent were captured in net 8, mesic graminoid herbaceous. High percentages were also captured in nets 7, closed broadleaf forest, 9, mesic graminoid herbaceous, and 11, open dwarf tree scrub.

Slate-colored Junco (n=1,723)—Captures were distributed evenly among all nets. This species was the most common migrant captured in open mixed forest.

Common Redpoll (n=119)—Twenty-six percent of Common Redpolls captured were in net 24. Habitat to the east was closed tall scrub, and to the west was broadleaf woodland. Twenty four percent were captured in net 21, open tall scrub.

Assessment of Sexing Criteria for Orange-crowned Warblers
Crown lengths less than 5mm in length (n=62) could be used to reliably sex females. Individuals with a crown >15mm could be accurately recorded as male (n=125). Crown lengths between 6-14mm could not be used for sexing Orange-crowned Warblers at CFMS.

Individuals with wing chords less than 57mm could be sexed female with 96% accuracy (n=57). Orange-crowned Warblers with wing chords of 60mm could be sexed males with 92% accuracy (n=47) and wings greater than 61 mm (n=125) could be used to sex males with 100% accuracy.

Tail length could not be used to accurately sex Orange-crowned Warblers.

Mortality
From 1992-1999, less than 0.44% of all birds captured died. Higher proportions of Black-capped Chickadees, Common Redpolls and Slate-colored Juncos died compared with other species. Primary causes of mortality included: predators (weasels, shrikes, raptors, squirrels), human error (mishandling), stress (in bags and nets), and poor banding conditions (cold mornings, rain).

EDUCATION
ABO worked cooperatively with the Alaska Department of Fish and Game to conduct environmental education programs for school, community, and tour groups. A curriculum designed by ABO was utilized to teach and inform students about the Alaska Bird Observatory, its mission, and the natural history of the Creamer’s Field Migratory Waterfowl Refuge. Visitors to the banding station were greeted by staff, interns, and volunteers and presented with a banding demonstration relating to avian ecology and conservation. During the course of the 2000 field season approximately 2,346 individuals visited the CFMS banding station. For more information, see the forthcoming education report.

NABC Bander Certification
On September 8-10 ABO hosted the Western Bird Banding Association’s annual meeting. Prior to the meeting, on September 7, the North American Banding Council offered a certification test for banders nationwide. The certification encompassed a test of field skills including banding, aging, sexing, net set-up and placement, and other aspects of banding. A written test covering regulations and ethics was also administered. Eleven banders participated in the certification process and nine were certified.

Volunteers
Ninety-one people volunteered at CFMS during the 2000 field season, contributing 2,275 hours of volunteer time to ABO. Volunteers at the banding station received training in removing birds from mist nets, net maintenance, bird identification, recording data, and handling birds for public demonstrations.

DISCUSSION

Analyses of data from standardized mist-netting stations indicate that migration-monitoring stations can provide information on the abundance and survivorship of migratory bird populations (Chase et al. 1997, Dunn et al. 1997, Johnson and Geupel 1996). The northern location of Creamer’s Field Migration Station allows us to examine the initial phase of autumn migration in Nearctic-Neotropic passerines. A more in-depth analysis of these data will answer questions relating to passerine migration that cannot be examined elsewhere in North America.

Management Implications
Understanding movements and population dynamics of passerines has become an international concern due to recent population declines throughout North America (Rappole and McDonald 1992, Askins et al. 1990). The importance of establishing baseline data for species has been recognized as vital in maintaining or regaining healthy populations (O’Connor 1992). Baseline monitoring allows resource managers to set management priorities (e.g., habitat preservation) based on scientific data. Long-term data collected at CFMS is important for understanding population dynamics of migratory songbirds in interior Alaska.

Habitat Use by Migrants
The data gathered for this project will be useful in evaluating successional changes in the habitat around nets at CFMS. Four of the nine habitat types are represented by a single net, an inadequate sample to examine habitat use. For example, several species were not captured in mixed forest, a habitat type that was not well sampled. In general, nets in open scrub habitats captured the greatest numbers of birds.

Nine of the 19 species were captured in all nine habitat types: Hammond’s Flycatcher, Black-capped Chickadee, Orange-crowned Warbler, Yellow Warbler, Yellow-rumped Warbler, Northern Waterthrush, Wilson’s Warbler, American Tree Sparrow, and Slate-colored Junco. All 19 species were captured in closed broadleaf forest, open broadleaf forest, open tall scrub, and mesic graminoid herbaceous. Thirteen of the 19 species were captured in closed mixed forest.
It appears that several species may rely on certain vegetative characters when migrating, however, a multivariate analysis of habitat data will be required to test this hypothesis.

Assessment of Sexing Criteria for Orange-crowned Warblers
Utilizing the lengths of crown, wing, and tail, particularly in combination with one another, will allow banders at CFMS to sex more Orange-crowned Warblers with greater confidence. The cut-off points differ from those given by Pyle (1997), indicating there may be morphological differences between the birds captured at Creamer’s Field and those used in his analyses. In the future we hope to conduct discriminate analysis on these variables together to develop a more accurate sexing tool.

Mortality
The percent mortality at CFMS from 1992-1999 (0.44%) is well below the accepted mortality rate of 1-2% (Gaunt and Oring 1997). Since 1997, the frequency of net checks has increased, likely decreasing the moralities occurring in the nets and bags.

RECENT PUBLICATIONS
Benson, A.M., T.H. Pogson, and T.J. Doyle. 2000. Updated geographic distribution of eight passerine species in central Alaska. Western Birds 31:100-105.

Benson, A.M. and K. Winker. 2000. Timing of breeding range occupancy among high-latitude passerine migrants. Auk: in press.

Benson, A. M. 2000. Temporal patterns of migration, molt, and fat storage among high-latitude passerine migrants. M. S. Thesis, University of Alaska Fairbanks, Fairbanks.

ACKNOWLEDGEMENTS

We gratefully thank all ABO members, volunteers and interns for their time and dedication. The Alaska Bird Observatory Scientific Advisory Council has provided invaluable expertise and guidance in research design. We also thank John Wright and Mark Ross of the Alaska Department of Fish and Game for their time and support. Keith Larson provided technical support in database management. This research was funded primarily by: the ABO membership; ABR, Inc.; ADFG; Arctic Audubon Society; ExxonMobil; Phillips Alaska Petroleum; and Ron and Mary Teel.

LITERATURE CITED

Askins, R.A., J.F. Lynch, and R. Greenberg. 1990. Population declines in migratory birds in eastern North America. Curr. Ornithol. 7:1-57.

Chase, M.K., Nur, N. and G.R. Geupel. 1997. Survival, productivity, and abundance in a Wilson’s Warbler population. Auk 114:354-366.

Dunn, E.H., D.T. Hussell, and R.J. Andams. 1997. Monitoring songbird population change with autumn mist netting. J. Wildl. Manage. 61(2):389-396.

Dunn, E.H., and D.T. Hussell. 1995. Using migration counts to monitor landbird populations: review and evaluation of current status in Current Ornithology, Vol. 12, (D.M. Power, ed.). Plenum Press, New York.

Gaunt, A.S. and L.W. Oring. 1997. Guideline to the use of wild birds in research: special publication of the ornithological council. The Ornithological Council, 1725 K Street, Suite 212, Washington, D.C. 20006-1401.

Hagan, J.M., III, T.L. Lloyd-Evans, J.L. Atwood, and D.S. Wood. 1992. Long-term changes in migratory landbirds in the northeastern United States: evidence from migration capture data. in: Ecology and Conservation of neotropical Migrant Landbirds, (J.M. Hagan and D.W. Johnson, eds.), Smithsonian Institution Press, Washington, pp. 115-130.

Hussell, D.J.T., M.H. Mather, and P.H. Sinclair. 1992. Trends in numbers of tropical and temperate-wintering migrant landbirds in migration at Long Point, Ontario, 1961- 1968, in: Ecology and Conservation of neotropical Migrant Landbirds, (J.M. Hagan and D.W. Johnson, eds.), Smithsonian Institution Press, Washington, pp. 101-114.

Johnson, M.D. and G.R. Geupel. 1996. The importance of productivity to the dynamics of a Swainson’s Thrush population. Condor 98: 133-141.

O’Connor, R.J. 1992. Trends in Population: Introduction in Ecology and Conservation of Neotropical Migrant Landbirds, (J.M. Hagan and D.W. Johnson, eds.), Smithsonian Institution Press, Washington, pp. 23-25.

Pogson T.H., A-M. Barber, S.L. McDaniel, and S.K. Springer. 1996. Creamer’s Field Migration Station fall summary report. Unpublished report submitted to the Alaska Department of Fish and Game

Pyle, P. 1997. Identification Guide to North American Passerines. Slate Creek Press, Bolinas California.

Rappole, J.H. and M.V. McDonald. 1992. Cause and effect in population declines of migratory birds. Auk 111:652-660.

Viereck, L.A., C.T. Dyress, A.R. Batten, and K.J. Wenzlick. 1992. The Alaska Vegetation Classification. USDA, Pacific Northwest Research Station.