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Common Loon

Common Loon Migration Update: February 26, 1998

Today's Update Includes:

Please report the FIRST loon you see this spring to Journey North!
Photo: Dr. F.G. Irwin

How to Track Loon Migration
Pull out your field guide so you're sure to know a loon when you see one. Then please report your FIRST loon of the season to Journey North.

If loons over-winter in your region, please report your "FIRST" loon NOW. We'll know by the date that your sighting was pre-migration. (Since our
computer can't add an extra category for "over-wintering" sightings, we ask
that you report these as "FIRST" sightings.)

News from the Wintering Grounds
While we wait for the loon migration to begin we'll have news to report while the loons themselves are preparing, thanks to two loon biologists who are stationed on Common Loon wintering grounds. Joe Kaplan and Keren Tischler will report in as they travel throughout Florida. Lucy Vliestra, who is stationed this year in Monterey Bay, California will report developments from the West Coast. Since it's now late February, they are noticing only the first subtle changes:

"The new breeding feathers with the white tips are just beginning to emerge, though they're still hidden by the winter coat," reports Joe from Florida. "Migration activity is slow for loons on the coast of California this time of year," adds Lucy. "Most loons are still in full winter plumage (brown-and-white) which means that they are still molting their wing feathers and cannot fly."

Birds of a Feather
For birds, molting is like changing clothes. Old feathers are shed and new ones grow back to replace them. With their long migration ahead, loons prepare by growing a set of strong, new feathers.

As you'll read below, loon biologists Joe Kaplan and Keren Tischler are actually collecting feathers of the birds they are studying in Florida. "Understanding how loons mature through molt (replacing feathers) is poorly understood," begins Kaplan, "but very important to our understanding of __________". How would you complete this sentence? Read more about Kaplan and Tischler's research below, then see if you can answer this question:

Challenge Question # 1
"If feathers can be collected from loons at different stages of maturity, what do you think they might help the biologist understand?"

Clue: The chemicals found in the feathers will be measured.

(To respond to this Challenge Question, please follow the instructions at the end of this report.)

Field Report from Loon Wintering Grounds in Florida

To: Journey North
From: Joe Kaplan
and Keren Tischler

February 21
"Greetings from Florida! We just got back from the Keys where we had great luck. We were able to capture 4 loons from the ocean and see several others in rehabilitation centers. Adult loons are beginning the flightless period. Some birds are losing worn-out flight feathers and other adults have begun to molt in a new set. The body feather molt has also begun. The new breeding feathers with the white tips are just emerging, though they are still hidden by the winter coat.

"The work we are doing in Florida has several objectives. We are interested in determining patterns of mortality on the wintering grounds, and also understanding how much the marine environment contributes to the Mercury burden of these loons. Based on molt patterns and plumage, we are working on methods to separate:
  • Hatch year loons from 1 and 2 year old loons,
  • And 1 and 2 year old loons from adults.

"If it sound confusing it is; understanding how loons mature through molt (replacing feathers) is poorly understood but very important to our understanding of _______________. (See Challenge Question #1 above.)

"We are currently networking with several wildlife care centers here in Florida to collect information on loons that come in for treatment. Unfortunately, a large percentage of loons that are brought into rehab centers die. We are making the best of this, and collecting as much information as we can on the cause of death. So far we have seen a few fish hooks, oil, and trauma from crash landings on wet roads. (The birds mistake these for bodies of water!) Mostly the cause of death is undetermined -- the birds simply starve.

"Next we're heading north into the Gulf. This is the heart of the loon country, where the greatest densities over-winter (at least in Florida). I suspect the availability of forage fish favors loons there, and probably the cooler waters. Loons usually get fairly scarce as you get south of Tampa Bay-- except this year.

"We are in the middle of a very strong El Nino event. I am not sure how conditions are different this year, but it is making loons more conspicuous further south. If I get to cross paths with an oceanographer I'll find out what is different this year.

Thanks for the interest in these loons. It is fun for us to share what we are seeing."

Joe Kaplan and Keren Tischler
Biodiversity, Inc.

Challenge Question #2
Since Joe and Karen are busy out in the field, maybe we can help them with their research. Have ocean temperatures in Florida been affected by El Nino? If so, how might this affect the loon food chain?

Challenge Question #2
"Please send a list of the best El Nino sites on the WWW which might help biologists Joe Kaplan and Keren Tischler understand El Nino's effect on Florida loons."

(To respond to this Challenge Question, please follow the instructions at the end of this report.)

Field Report from Loon Wintering Grounds in California

To: Journey North
From: Lucy Vliestra

February 23, 1998
"Hello from Monterey, California. Migration activity is slow for loons on the coast of California this time of year. Most loons are still in full winter plumage (brown-and-white) which means that they are still molting
their wing feathers and cannot fly.

"Last week, however, I did see a couple signs of spring. One common loon seemed to appear from nowhere in nearly full black-and-white plumage! I regularly visit that site and before that day had not seen any signs of changing plumage. So, this loon may already have been traveling north up the coast, stopping briefly in Monterey Bay. I have not seen it since. A few common loons are showing black feathers on their face, which means they are starting to put on breeding plumage, but these loons are still rare.

"Yesterday, I saw the first sign of breeding plumage in a Pacific loon (Gavia pacifica). Vertical stripes were easily distinguishable along the length of its neck. It will be interesting to see whether common loons and Pacific loon prepare for migration at the same time.

"I expect that in just a couple weeks more loons will molt into breeding plumage and before too long, some common loons may even fly, getting their wing muscles ready for migration.

"I am studying community structure with respect to prey distribution among piscivorous birds in Monterey Bay. My focus is on common, Pacific, and red-throated loons. Among my tasks here I conduct surveys of all 3 loon species from a boat. I have transects located 1 and 2 miles offshore,
throughout the southern and central part of Monterey Bay. I rig the boat with hydroacoustics equipment that measures fish distribution using sonar. This allows me to directly compare the distribution of fish with the distribution and behavior of fish-eating birds.

"We have just had an impressive wave of gray whales moving through Monterey Bay. They are easily visible from shore and during the last two weeks in January, Gray whales were a common sighting all along the shores of the Bay. The Monterey Canyon, comparable in size to the Grand Canyon but underwater, bisects the Bay into northern and southern halves. Apparently, the whales do not cross the deep water canyon, but rather follow the shallow water along the perimeter. Because the head of the canyon starts very close to shore, the whales end up swimming very close inshore, and sightings can easily be made from our beaches.

"In late January, I saw many Gray Whales, spouting and one even breached. But I haven't seen a whale for a couple of weeks, although whale watching boats still go out often on the Bay. I hear that at this time of year at this location, the first whales heading north are crossing paths with the last whales heading south which is why we get such good looks at these amazing animals."
Until next time,
Lucy Vliestra

How to Respond to Journey North Loon Challenge Questions:

Please answer ONLY ONE question in each e-mail message:

1. Address an e-mail message to:

2. In the Subject Line of your message write: Challenge Question # 1 (OR #2)

3. In the body of the EACH message, give your answer to ONE of the questions above.

The Next Loon Migration Update will Be Posted on March 12, 1998.

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