Midwinter Bald Eagle Count USGS NBII

Select Summary Trend Information:
by State or by Ecoregion or by Region

Table 1. Number of survey routes and surveys used in the analysis, with estimated trends in the eagles counted, midwinter, by state. (Download)

State	Routes	Surveys	Years	Trend
Alabama	3	42	1986-2000	-6.0%
Arizona	51	373	1992-2000	-1.6%
Arkansas	12	86	1986-2000	+0.3%
California	6	51	1986-2000	+3.2%
Colorado	32	312	1986-2000	-1.1%
Connecticut	8	76	1986-2000	+3.2%
Delaware	1	10	1989-1999	+4.5%
Georgia	3	22	1989-2000	-2.9%
Idaho	68	840	1986-2000	+1.9%
Illinois	14	62	1996-2000	+6.6%
Indiana	22	204	1986-2000	+3.3%
Iowa	42	282	1986-2000	+5.6%
Kansas	13	134	1986-2000	+1.5%
Kentucky	13	88	1986-2000	+2.0%
Louisiana	4	28	1986-2000	-2.4%
Maryland	3	40	1986-2000	+5.4%
Massachusetts	4	42	1986-2000	+3.7%
Michigan	3	31	1987-1998	+9.0%
Minnesota	4	49	1986-2000	+7.6%
Montana	4	40	1986-1997	-2.5%
Nebraska	2	29	1986-2000	+5.9%
Nevada	5	25	1992-2000	-2.4%
New Hampshire	4	29	1991-1999	+7.1%
New Jersey	17	165	1988-2000	+4.7%
New Mexico	41	284	1990-1996	-0.3%
New York	2	30	1986-2000	+8.3%
North Carolina	2	14	1987-2000	+0.9%
North Dakota	1	15	1986-2000	-4.4%
Ohio	1	5	1996-2000	+12.3%
Oklahoma	30	277	1986-2000	+0.9%
Oregon	78	801	1988-2000	+1.4%
Pennsylvania	4	35	1986-2000	+1.8%
South Carolina	10	70	1993-2000	+3.3%
South Dakota	4	49	1986-2000	-0.1%
Tennessee	6	86	1986-2000	+2.0%
Texas	19	189	1986-2000	+0.9%
Utah	16	187	1986-2000	+0.1%
Vermont	1	8	1993-2000	+7.3%
Virginia	2	8	1997-2000	+4.5%
Washington	2	27	1986-2000	+4.6%
West Virginia	1	5	1995-2000	+5.4%
Wisconsin	5	30	1991-2000	+0.2%
TOTAL	563	5180

Table 2. Estimates of percent annual change in midwinter Bald Eagle counts by ecoregion, 1986-2000 (n = 563). Asterisks indicate trends significantly different from zero. (Download)

Ecoregion	% Annual Change	95% C.I.
East Coast^a	+3.6%	1.3 - 5.9*
Eastern Woodland^b	+2.5%	0.6 - 4.3*
Great Basin^c	+1.3%	-0.4 - 3.0
Great Lakes^d	+7.0%	3.5 - 10.6*
Gulf^e	+1.4%	-0.8 - 3.6
Pacific Coast^f	+1.6%	-0.4 - 3.5
Prairie^g	+3.2%	1.5 - 4.8*
Rockies^h	-0.3%	-1.8 - 1.3
Southwest Desertⁱ	-1.2%	-3.9 - 1.5

^aSoutheastern Coastal Plan (27) and New England/Mid-Atlantic Coast (30)

^bAtlantic Northern Forest (14), Central Hardwoods (24), Appalachian Mountains (28), and Piedmont (29)

^cGreat Basin (9) and Sierra Nevada (15)

^dBoreal Hardwood Transition (12), Lower Great Lakes (13), and Prairie Hardwood Transition (23)

^eOaks and Prairies (21), West Gulf Coastal Plain (25), Mississippi Alluvial Valley (26), and Gulf Coastal Prairie (37)

^fNorthern Pacific Rainforest (5) and Coastal California (32)

^gPrairie Potholes (11), Badlands and Prairie (17), Shortgrass Prairie (18)

^hNorthern Rockies (10) and Southern Rockies (16)

ⁱSonora and Mohave Deserts (33), Sierra Madre Occidental (34), and Chihuahua Desert (35)

Table 3. Estimates of trends in the midwinter bald eagle count and proportion of survey routes with increasing trends by region, 1986-2000. (Download)

Region^a	No. Routes	Trend estimate^b	Standard error^b	P-value	Change per year^c	Routes with increasing counts
Overall	563	0.0192	0.005	0.000	1.9%	65%
North	267	0.0348	0.008	<0.001	3.5%	73%
South	296	0.0037	0.007	0.619	0.4%	58%
East	253	0.0367	0.008	<0.001	3.7%	78%
West	310	0.0017	0.007	0.808	0.2%	55%
Northeast	98	0.0590	0.013	<0.001	6.1%	90%
Southeast	155	0.0145	0.009	0.104	1.5%	70%
Northwest	169	0.0106	0.008	0.183	1.1%	63%
Southwest	141	-0.0072	0.012	0.540	-0.7%	45%

^a Regions defined in relation to 40^o N and 100^o W.

^b Calculated from logged counts.

^c Estimated from actual counts (back-transformed).