Common Loon Migration Update: April 10, 1997

Dr. F.G. Irwin

We hope to hear soon about Dave Evers' attempts to capture and track a loon this spring by satellite telemetry. When news arrives, we will post an update immediately. Otherwise, watch for our next migration update on April 24th. In the meantime, here's wishing good luck to Dave & his team!

We caught up with Lucy Vliestra who has just returned to New York State. "I would expect Dave's chances of catching a loon are quite good, in that 'territorial/breeding' hormone levels may be higher in the spring than in mid-winter," said Lucy. (Those hormones regulate the loons' chick-guarding behavior, and the capture process is facilitated by this parental behavior in the summer. This is because the biologists imitate the distress calls made by loon chicks, causing the adult loon to come close to the capture boat.) "However, there are not as many birds around and they may be harder to find. By the time I left April 6th, the loons were somewhat fewer in number, but many adults were still hanging around. A large portion was in breeding plumage, but some were still just in the initial stages."

Lucy is now beginning to analyze her time budget data to see what kind of pre-migratory behavioral differences may have occurred as spring progressed. Thanks for keeping an eye out for us on the loons wintering grounds, Lucy!

• Link to Today's Migration Data.

Another 28 loon sightings have been reported since our last update. To chart the movement of loons this spring, we suggest using color to portray time. Self-adhesive, color-coded labels come in various sizes and work well. Use different colors to show intervals of time. For example, loon sightings could be marked according to this color scheme:

A legend explaining your use of color will help readers see how the migration progresses over time. In addition to marking with color, you can write the exact date of each sighting on the label. This will give a more detailed picture for people who look at your map closely. Since the labels will cover the name of places on the map, you may want to make a date/location table and post it beside your map.

Try This
Count the number of loon sightings reported during each time interval and record the number on the chart below.

• During which time interval were the most loons reported?
• How do you interpret this?
• Can you correlate these trends with any weather patterns?
• Consider how the data were collected. What factors might influence the number of loons reported?
• At the end of the season, write a report summarizing this spring's migration. Describe the trends shown by the numbers. Be sure to mention the factors you believe influenced the data.

Important Note: People often report their sighting a week or so AFTER the date of the sighting. Therefore, wait awhile before summarizing the data for each weekly interval.

The Next Loon Migration Update Will be Posted on April 24, 1997.