Monday, May 26, 2014

Territory Wars

This summer is off to an interesting start.  The birds arrived a month ag,o but they spent quite a long time at the beginning of nesting before the first female was ready to lay her eggs.  This is possibly because the temperatures have been slightly lower than normal.

Possibly because of this late start, most sections of the field site are in a state of territorial unrest.  Both males and females are involved in these territory fights.  Two days ago we mist netted the male at B5.  After we caught the male, we played female playback to try and get the female.  We caught an intruding male instead!  It will be very interesting to get the genetic results back from the offspring to see whether the territorial male or the intruder fathered the egg she laid the next day.

At C5 two females have been having a week long fight.  The female initially banded there lost her territory for several days to an unbanded female that laid several eggs.  However, on the 4th egg laying day the old female had tossed all the eggs on the ground and reclaimed the territory.  How do we know a wren got the eggs?  Notice the tell-tale beak-sized punctures in the egg below.

Egg found on the ground in front of box C5 with several puncture wounds from a female wren beak.
For one of my experiments this summer, I'm kicking birds off territories to increase the number of floating birds that can challenge territory holders.  I'm hoping to determine whether females that are more aggressive in my tests are able to keep their territories longer.  Although I have only evicted 3 pairs so far, the birds seems to be doing a good job of this themselves.  I might also be getting a helping hand from the resident mammals.  Destruction of the box at B3 by a flying squirrel appears to have set off a chain reaction of territory switches in the B's and C's over the past week.  

   Massive mammal damage to the box at B3

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