Friday, May 14, 2010 5:58am CDT


45 degrees   Cloudy   Wind W 9mph


Under a clear sky, the first sunshine we have seen in days is brushing the nest with its rays.  And the loon sits faithfully on its eggs.  For now.

We have just been through a confrontation with another pair of loons during which time our loon was drawn off the nest for about 12 minutes and then about 3 minutes.

This time there were no calls.  The loon on the nest simply left.  It had been holding its head in a defensive posture for a minute or so and then it left to swim out to meet its mate and the other pair of loons.

The four of them circled and circled and dived excitedly.

When one would dive, the others would dive.  Over and over this ritual was repeated.

This is one of the times of greatest vulnerability for a loon.  It is when a male loon can do great damage to the other male loon in this fight over who controls this territory.

I have talked before about the loon's long sharp beak being its most potent weapon.  And it is used for both defense and offense.  One loon can come up from beneath another loon and do what is called a 'sternum stab'.  That is just what it sounds like.  The loon underwater stabs the loon on the surface of the water in the sternum!

There have been cases documented where one loon has killed another loon in this way.

So in a confrontation, when one male loon dives underwater, the other male will also usually dive as well.  It is his way of protecting himself from a sternum stab.  If they are both underwater, each one can keep an eye on the other and they are not as vulnerable to an attack from below.

Well, our pair of loons has ushered the other pair off to the east.  Apparently they have gotten them far enough away from the nest that they feel comfortable swimming back toward the nest.  Only now are there several tremolo calls.  That is somewhat unusual in that there had been no calls during the whole confrontation.

One of the loons got back on the nest after 12 minutes off.  But after only a minute, she was back off for 3 more minutes - apparently wanting to satisfy itself that this 'intruder pair' was actually gone.

Some of you have questioned whether this was the same pair as was here last year.  I will be honest, I have wondered the same thing!

There is no one thing that makes me think that but a series of small changes in behavior that make me wonder.

There was the long extended chase several weeks ago.  One of the loons has a distinct "break" in its call that I had not heard before.  The fact that there was serious nest building at one point only for it to take 2 more weeks for them to lay eggs.  Being back to the lake 2 weeks early but nesting later than I expected [remember how many of you were worried if they were even going to nest and I was trying to reassure you that they were?!].  Well, I will be honest with you....I was having some of the same questions at the time!

The observation that there seems to not be quite the same dedication to always being on the nest.  Remember the morning with heavy frost on the nest when she was off for about half an hour?  Now granted that was because of another confrontation with the intruder loons.

But just the fact that we still have another pair of loons on the lake makes me question which pair is the one we have seen in previous years.  It is one of many reasons why I would so like to band the loons.

Some have raised the question of whether the other loons on the lake might be loons from a previous year's hatch.  I have wondered the same.

Typically loons will stay down on the Gulf of Mexico or the Atlantic shore for the first 2 or 3 years of their lives.  Only after that will they come back north.  And the conventional wisdom is that they will come back to the same lake on which they were hatched.  So that alone sets up the scenario for confrontation.

But also, loons do not reach breeding maturity until they are about 5 or 6 years old.  So if one of these pairs is from previous years, it may be from 5 or 6 years ago.  We can only guess!

Because of their nearly identical markings, it is almost impossible to distinguish one loon from another.  In fact, it is almost impossible to distinguish the male from the female they look so much alike.  If you see or hear a loon yodel, then you can be sure it is a male since only the male uses the yodel call.  But otherwise, it is almost impossible to distinguish one from the other.

Some have seen the obvious 'bump' on the forehead at the base of the beak and used that to distinguish one from the other.  I also have done that.  But upon closer observation, it does not seem to be an actual 'bump' but that they can raise feathers in that area.  I have always thought that the male had that 'bump' but it seems to be both that can have it at certain times.  And at other times, both of them have a 'smooth profile'.  I would like to at some time examine a loon closer to see if there is an actual bump there or if it is entirely feathers.  I have never seen anything in the ressearch literature about this 'bump'.

Ok, that is probably more than you ever wanted to know about loons and intruders and confrontations and fights and chicks from previous years and 'bumps'!

But it gives you yet more insight into these amazing birds we call loons!