Dozens of territorial pairs in our study area are now on nests. Several pairs have failed. Early indications are that failures this year will be caused mainly by predation. Raccoons are the most frequent culprit, according to work done by the DNR in our region using nest cameras. In spite of the havoc wreaked by raccoons, we still hope for a high rate of hatch.
Territorial visitors are a common sight on breeding territories these days. They will become increasingly common as the season wears on. Many lake residents wonder who these territorial intruders are and what they are doing. These loons are not, as many folks surmise, chicks that have matured and are returning to visit their parents. They are true territorial intruders — individuals that are young and have never possessed a territory or are older and had one but were booted off of it by another loon. Intruders intrude to learn about the territory and its defenders, primarily because they hope to usurp the territory by force on this or a subsequent visit.
One interesting pattern that we have seen in the last few years among intruders is a higher rate of long-distance intruders. For example, On Big Carr Lake a few days ago, we saw a female from Moon Lake in Vilas County. This is a bird banded by my collaborator, Mike Meyer of the DNR. More recently I identified a 5 year-old intruder from Powell Marsh: again, this was a DNR-banded bird from up in Vilas County. Of course, we value every banded intruder, as each gives us an opportunity to track a loon’s movements and the strategy it uses to gain a breeding slot. But the long-distance intruders are especially valuable, because they are chiefly females, which disperse much longer distances than males, on average, and which, therefore, we have learned less about.
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!
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 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.
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.