THE CHICKADEE COUPLE DOES A CAVITY!

 All times PM
6:07:48  I'd gone outside to look for the rabbit.  We're still in the middle of that Rabbit Saga, so he will appear on another day when I get him figured out.  When I noticed that a pair of Black-capped Chickadees where whipping in and out of a hole in the top of an old lilac tree.  Hmmm.

And I mean whipping, as in switching places at the hole every few seconds.  In fact so fast on the in and out I was having trouble catching them in the act.

Can you see the Chickadee in the above picture?

Not easily.  The same problem I was having so I'll edit the pictures lighter than the reality so we can try to figure out what is going on up there.

 Basically the pair was rapidly double teaming activity at this hole One would enter the hole, pop back out, fly to a near-by twig, while the second  popped in and out.  Then the first would do it again, fast as lightening, and the second would do the same. 

My question...what are they actually doing?

 6:08 This is a different Chickadee.  I haven't been able to catch them on the exit yet.  In fact I miss entrances as well.  These guys are like lightening.

6:08:10  Another switch.

6:08:15 And another.

 6:08:36  Missed a couple of switches.  But here is an example of how close the outside bird perches while the inside bird does whatever he or she is doing.

 6:08:50 Missed the action.

Missed it again!

6:09:05  Got 'em going in!  But not coming out.

6:09:28  Inside.  You get the idea so we'll deal with the times I do catch them at it. 
The new wrinkle is they aren't now disappearing completely into the hole.

6:09:48  Similar posture then a quick exit.

6:09:43 Then just the bird's head goes in.

 6:09:54  I get a look before she goes back to business.

6:10:11  Here's a perched bird waiting for her turn.

6:10:18

 Note a somewhat similar hole further down the trunk, though it does not appear to have the depth of the upper hole.  Do Chickadees often have a second possible choice as Red-tailed Hawks do?

Note the two starter holes on the trunk  above the bird's head.

Okay, Chickadee is now in the hole sideways, both legs coming out left,  and tail braced at the bottom.

One leg inside and one leg outside.

The one leg now appears to have receded into the hole a bit.

The mate watches with intent interest.

 More gyrations inside the hole.

TO BE CONTINUED!