21 May 2013
Loons have their own dedicated species of blackfly, Simulium annulus, that depends on them for a blood meal prior to reproduction. Many of the pairs I have observed on recent days have spent their time on the surface in a fruitless effort to shake or toss their heads to rid themselves of these nasty blood-suckers. At this point, we have found five pairs that have just initiated nests. It will be interesting to see if the loons can continue to incubate despite the unpleasantness of the flies. Though it has not yet been shown experimentally, we strongly suspect that blackflies cause the high rates of nest abandonment of early loon nests in many years. We hope that this pattern will not recur in 2013.
11 May 2013
I return to the study area from California. I am excited to see all of my friends — loon and human! It will be an eventful first few weeks for the project. Joel Flory has been working steadily to ID mated pairs and keep me apprized of ice conditions, especially in the southern part of the study area. Kristin and Gabby came down from Northland for a weekend to help ID returning loons and covered a lot of ground. But they are both graduating this year (well….fingers crossed ), leaving Joel and me alone to cover over 100 lakes until the end of the month. My back hurts already!
2 May 2013
The lakes are opening, and 4 May (Saturday) is our first full day out covering the study area. We appreciate the reports we have gotten from many of you about the status of ice on your lakes. Kudos to some folks who have raised the bar by verifying all color bands on their territorial pairs already. Awesome! We have gotten reports from DNR that many loons have become stranded this year because of poor weather and few open lakes and have landed in puddles from which they cannot fly out. (These birds are being reported and are getting help.) Keep Wild Instincts (wildlife rehabbers near Rhinelander) in mind, if you see loons in trouble.
We are waiting impatiently for ice-out, which, it seems, will not occur until May this year. That would be the latest since 1996. Gabby, Kristin and Joel Flory will be covering study lakes early in the year — once they finally open up. Give them a wave if you see them out in their canoes, braving early spring conditions. I will be up myself in early May to help learn which of our loons have returned from the winter and to train the new crew members. Maybe I will see you!
Gabby Jukkula wrote up a behavioral study she and Kristin Brunk did last summer and won an award for best undergraduate paper at the Wisconsin Chapter of the Wildlife Society! Congrats to Gabby for this awesome accomplishment — and to Gabby and Kristin both for the work they put in last summer to complete the work.
We mailed out our annual loon letter to friends and lake-dwellers who help us get access to study lakes and support our work. If you are in this category but have not received our letter, please e-mail or call me, and I will get you a copy. Make sure, too, that I get your mailing address for future years.
I presented a talk at a conference in Colorado on my examination of the “foothold model”, which attempts to explain how young animals settle on territories. The model supposes that a young animal settles within a home range that includes territories defended by several established breeders, wait for one of them to die, and then take ownership. Critically, it is the period of residency of a young animal within the defended territories that allows it to claim the breeding vacancy that becomes available, according to the model, because during this period the young animal accumulates site-familiarity and a “home-court advantage” within those territories. By this means, it is able to compete successfully for the breeding slot against other young animals. Although the model is intuitive and interesting and appears to apply to several other species of birds, loons do not seem to settle this way. Lack of tolerance of territory owners for young loons appears to prevent a home-court effect, so the pattern can never get started. Instead, young loons seem to visit many territories for brief periods in order to size up the owners and engage in territorial battles with owners they think they can defeat. Since they cannot gain a home-court advantage anywhere, it is simply the strength and fighting ability of a young loon that allows it to fight successfully in such cases.
We made systematic efforts in 2012 to relocate chicks that we had marked in July and August. This effort will allow us to learn to what extent chicks remain on their natal lakes or wander to other lakes nearby. This topic is of particular interest to us, because it is possible that, by exploring and becoming familiar with the lakes near their natal lake, chicks lay the groundwork for their return to the study area at ages 2 to 4 years. Thus, their movement patterns while juveniles might help us predict where they will settle down the road.
We have completed another year capturing and color-banding adult breeders and their chicks. Altogether, we captured and marked 57 chicks and 50 adults.
In a separate effort, we measured pH and clarity (via secchi disk) twice for all of our study lakes. These data provide a crude measure of water quality and also an important baseline against which to compare future values of acidity and clarity.
We heard that the National Science Foundation grant that supports our work was renewed for five more years. We are excited to continue learning about loon territoriality and population stability. If our backs hold out, we will be able to share a good deal more with you about the loons on your lakes.
Our article on juvenile survival in loons just came out. Based on the hundreds of loons that we banded as chicks and have reobserved as adults in the study area, the paper reports that about half of all loon chicks return to the breeding ground as adults. Most of these individuals are seen within 15km of their natal lakes.