Alaska Bird Observatory

Creamer’s Field Migration Station: Fall Report 1999.
28 October, 1999

David W. Shaw, Banding Biologist, and Anna-Marie Benson, Migration Program Manager
Alaska Bird Observatory, Box 80505, Fairbanks, AK 99708

Submitted to: John Wright, Alaska Department of Fish and Game, 1300 College Road, Fairbanks, AK 99701
Ruth Gronquist, Bureau of Land Management, 1150 University Ave, Fairbanks, AK 99709

The Alaska Bird Observatory (ABO) has operated a large standardized mist-netting station at Creamer’s Field Migratory Waterfowl Refuge in Fairbanks, Alaska from 1992-1998. 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, juvenile 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 sites 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 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 Bureau of Land Management (BLM) nongame migratory bird habitat conservation program, 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.

Field methods have remained constant during eight years of migration banding at CFMS. Nets were opened at sunrise and closed seven hours later or as late as 1400 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 were calculated (birds/1000 net hours) 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).

Summary 1999

We banded 3,945 birds of 32 species during the fall migration of 1999. Nets were operated for approximately 12,111 net hours (one net open for one hour). As in previous years, the most abundant species were Myrtle Warblers, Orange-crowned Warblers, American Tree Sparrows and Slate-colored Juncos (Table 1). These species comprised 63% of all birds banded. We also captured two Three-toed Woodpeckers, which are uncommon species at the study site.

Relative Abundance

Population indices were calculated for each species from data collected during eight years of banding (Table 2). We examined preliminary trends in abundance (Table 3, Appendix 1. Figures 1-19), but caution that many more years of data are required to predict long-term trends. A significant trend in avian abundance was only detected in one species, the Fox Sparrow. This species displays a significant, positive increase in annual population indices (n=8, P<0.01).

Education

ABO worked cooperatively with Alaska Department of Fish and Game to schedule school, community and tour groups. A curriculum designed by ABO was utilized to teach and inform local school groups about the Alaska Bird Observatory, its mission, and the natural history of Creamer’s 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 1999 field season approximately 3,500 individuals visited the CFMS banding station. See the enclosed education report for more details.

Volunteers

In 1999 ninety people including 6 youth, volunteered at CFMS, contributing 2,119 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.

Table 1. Number of birds captured at Creamer’s Field Migration Station, Fairbanks AK: 1992-1999
Species	1992	1993	1994	1995	1996	1997	1998	1999	Total
Northern Harrier	0	0	0	0	1	0	1	0	2
Sharp-shinned Hawk	3	2	1	3	8	3	14	6	40
American Kestrel	0	0	0	0	0	1	0	0	1
Merlin	0	0	0	0	0	0	2	0	2
Lesser Yellowlegs	0	0	0	0	1	0	0	0	1
Common Snipe	0	0	0	0	0	0	2	0	2
Downy Woodpecker	1	0	3	2	1	1	1	2	11
Hairy Woodpecker	0	0	0	1	3	1	1	2	8
Three-toed Woodpecker	0	3	1	0	0	0	0	2	6
Black-backed Woodpecker	0	0	0	1	0	0	0	0	1
Northern Flicker	0	0	0	0	2	2	0	1	5
Western Wood-Pewee	1	0	0	1	0	3	0	0	5
Yellow-bellied Flycatcher	0	0	0	0	0	1	1	0	2
Alder Flycatcher	36	75	62	64	68	124	57	45	531
Hammond's Flycatcher	9	13	40	49	86	71	34	30	332
Tree Swallow	0	0	0	0	1	0	0	0	1
Cliff Swallow	0	0	0	0	0	1	0	0	1
Gray Jay	0	1	0	1	1	0	0	0	3
Black-capped Chickadee	36	24	27	62	46	32	44	42	313
Boreal Chickadee	1	10	5	6	11	6	14	0	53
Red-breasted Nuthatch	0	0	1	2	1	0	0	0	4
Arctic Warbler	0	0	4	1	1	5	3	4	18
Golden-crowned Kinglet	0	0	0	1	0	0	1	0	2
Ruby-crowned Kinglet	55	89	127	123	233	196	139	62	1024
Gray-cheeked Thrush	39	25	28	50	16	40	40	49	287
Swainson's Thrush	66	91	102	176	89	185	107	128	944
Hermit Thrush	6	5	7	15	20	18	24	19	114
American Robin	170	20	37	34	36	37	23	33	390
Varied Thrush	25	3	3	1	12	6	6	3	59
American Pipit	2	0	0	0	0	0	0	0	2
Bohemian Waxwing	5	0	0	0	0	0	1	0	6
Northern Shrike	0	1	1	1	2	0	3	4	12
Orange-crowned Warbler	458	233	597	865	456	637	918	672	4836
Yellow Warbler	134	59	89	196	114	186	84	194	1056
Yellow-rumped Warbler	835	56	1001	588	1164	1232	1351	687	6914
Townsend's Warbler	3	2	2	3	5	10	5	3	33
Blackpoll Warbler	86	21	49	51	49	102	44	170	572
Northern Waterthrush	43	30	17	28	33	49	40	49	289
Wilson's Warbler	133	108	116	169	75	186	153	127	1067
American Tree Sparrow	112	395	343	660	274	757	1203	727	4471
Savannah Sparrow	47	72	28	174	83	103	95	201	803
Fox Sparrow	16	30	42	32	37	66	70	70	363
Lincoln's Sparrow	179	149	177	362	233	246	284	134	1755
Golden-crowned Sparrow	2	0	0	0	2	0	2	4	10
White-crowned Sparrow	43	41	60	43	120	69	97	32	505
Dark-eyed Junco	144	162	535	413	578	456	816	414	3518
Lapland Longspur	0	0	0	0	0	0	0	0	0
Rusty Blackbird	1	1	0	0	50	1	4	1	58
White-winged Crossbill	0	0	0	0	0	0	0	0	0
Common Redpoll	2	0	17	164	47	5	69	28	332
Hoary Redpoll	0	0	0	5	0	0	0	0	5
Total Number Banded	2684	1721	3523	4346	3958	4839	5753	3945	30769
Net Hours	5890	13712	13935	14156	14985	14617	12091	12111	101497

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

Table 3. Summary of linear regression analysis to examine trends in abundance for 19 passerine species at CFMS from 1992-1999. Correlation coefficients (r) measure the relationship between year and population index, b values indicate the slope of the predicted line, and F-statistics indicate significance of regression models.
Species	n	b	r	F	P
Alder Flycatcher	8	-0.05864	0.15	0.15	0.72
Hammond's Flycatcher	8	0.10163	0.40	1.15	0.32
Black-capped Chickadee	8	0.40229	0.44	1.44	0.28
Ruby-crowned Kinglet	8	0.09876	0.17	0.18	0.69
Gray-cheeked Thrush	8	-0.00906	0.03	0.01	0.95
Swainson's Thrush	8	0.09879	0.24	0.38	0.56
American Robin	8	-0.03558	0.31	0.64	0.45
Orange-crowned Warbler	8	0.13034	0.05	0.01	0.91
Yellow Warbler	8	-0.09899	0.14	0.12	0.75
Myrtle Warbler	8	0.73113	0.14	0.13	0.73
Blackpoll Warbler	8	0.03579	0.13	0.10	0.76
Northern Waterthrush	8	-0.18192	0.42	1.30	0.30
Wilson's Warbler	8	-0.31627	0.53	2.30	0.18
American Tree Sparrow	8	0.66884	0.22	0.29	0.61
Savannah Sparrow	8	0.35650	0.55	2.59	0.16
Fox Sparrow	8	0.13790	0.87	18.62	<0.01
Lincoln's Sparrow	8	-0.38174	0.19	0.23	0.65
Gambel's White-crowned Sparrow	8	0.03821	0.09	0.05	0.83

Analyses of data from standardized mist-netting stations confirm the usefulness of this method for studying 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 Neararctic-Neotropic passerine species. A more in-depth analysis of these data will answer questions relating to passerine migration that cannot be answered 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 1994, 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 land 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.

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: ABO membership; ABR, Inc.; Alaska Department of Fish and Game; ARCO Alaska, Inc.; Arctic Audubon Society; BLM (Cooperative Agreement #1442L320A7-2005); Exxon Co., USA; and the Skaggs Foundation. ADFG also provided in-kind support.

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