January 31, 2010 Eagle Roost Count
gengberg February 2nd, 2010
Hello all of you fine eagle enthusiasts:Our count yesterday was precisely the same as we tallied two weeks previous: 59 birds. The distribution of birds along the river, however, was inverse to the distribution tallied on January 17. Yesterday few eagles were seen upriver with Blackhawk, Sugar Loaf and Ferry Bluff Roosts all reporting few birds. 
Further downstream Fox Roost held 8 eagles but then only one eagle was seen at Jones Slough and no eagles were seen at McDonald Roost. At the farthest downstream roost that we monitor, Lone Rock, 27 eagles were tallied; almost three times the number of eagles seen two weeks ago. Off-river roosts of Leland, Big Hollow, and Ederer/Been varied little from two weeks ago in eagle numbers. Sharon Reilly also recorded seeing 4 eagles in the Baraboo area yet, about the same as during our last count. Interestingly, one week ago I saw 10-15 eagles soaring around the Sugar Loaf Roost so this change in eagle distribution may have occurred primarily in the last week. Photo by Mitch Spillane
Along the river eagle distribution shifted back from upriver to downriver, presumably as ice cover in the river opened up some. From places that I have observed the river (i.e. near Arena), I have not seen much open water so most openings in the ice likely occur downstream from Spring Green. Conversely, upriver areas have not acquired much ice but eagle numbers do not persist there currently when downriver areas become more available.
Many have written to suggest that snow conditions are likely to have an influence on eagle distribution over the past three winters. The last three winters have had larger than normal amounts of snowfall and this snow has persisted for longer periods of the winter. Perhaps more extensive snow cover renders much eagle habitat unavailable by covering up food resources but I am curious as to why eagle numbers would not increase in the off-river roosts during the last two weeks. Over the last two weeks the Sauk Prairie area has lost a large amount of snow, perhaps half the depth while southern slopes are becoming snow free. The last two weeks have had little new snow accumulation and, though cold, much snow has sublimed or melted under clear skies. With less snow cover, hidden animal carcasses would likely be exposed but little evidence of this has been seen in eagle numbers off-river. Our off-river eagles counts did not change from Jan. 17 to Jan. 31.
Contrary to my speculation here, DNR biologists conducting aerial deer surveys have noted greater than average eagle numbers along smaller rivers in southern Wisconsin like the Pecatonica and Sugar Rivers. For example 20 eagles were seen January 20 during aerial surveys in southern Iowa and Lafayette County. One of the exceedingly difficult variables to measure for eagles is food availability over such large areas, especially as land use changes over time. It is impressive to glimpse the flexibility that eagles have in adapting to a changing landscape even while they also traditionally use winter areas like the Lower Wisconsin River.
Though 59 eagles is a small number of birds compared to the last decade of counting, maximum eagle numbers for the entire winter in the 90’s were as low as 52 birds (winters of 90/91 and 93/94) and often did not exceed 85 eagles. Our maximum number of eagles counted so far this year was 101 eagles, tallied on January 3. Depending on weather conditions, more eagles might still be counted in February.
Finally, the following eagle news may be of interest as well:
> From: joan schnabel/jeff falk
> Subject: [wisb] Golden Eagle survey results
> To: “Wisbird Network”
> Cc: “Scott Mehus”
> Date: Friday, January 22, 2010, 7:30 PM Preliminary results from the
> 6th annual wintering Golden Eagle Survey Jan 16 are 85 Golden Eagles,
> 635 Bald Eagles and 284 Red-tailed Hawks. One hundred thirty-five
> people participated in the survey including many readers of the
> Wisbird Network and MouNet. Thanks to everyone who helped on this, and
> especially Scott Mehus for believing that these birds were here and
> getting us all organized. Save the date for the 3rd Sat in January of
> 2011. Joan Schnabel Fountain City WI
