Saturday, April 6, 2013

Two Song Sparrows' Curious Confrontation

I taught the second of my birdsong identification class/listening hike combinations at the Holden Arboretum on March 30th . After the three-hour program was over, I went right back out on the trails to follow up on some of the interesting things I’d heard and seen.  I came upon two Song Sparrows singing on opposite side of the path in the Holden Arboretum display garden.  This is Song Sparrow #1...

....and this is Song Sparrow #2.

They were unusually close to each other for two males who had established their territories, and each one’s song began promptly upon completion of the others' song. The responses were so immediate that it sounded as if I were hearing two phrases of the same song – an antecedent phrase followed by a consequent phrase.

Then Sparrow#1 changed his song.  Sparrow #2 was on the ground appearing to forage for food.  Sparrow #1 promptly flew down next to Sparrow #2 and sang his new song, but softly. Here is #1’s new song and the soft song and chip notes that followed.  

They foraged within a few inches of each other, with Sparrow #1 flying up just a little, singing his song, then dropping down right next to #2 and singing softly.  Both flew up a little above the ground - still near each other – and I heard many high “chip-chip” call notes.  The soft song was the same tune that #1 had been singing up in his tree, and singing was interspersed with more rapid, high chip-chips from both birds.

Sparrow #1 began singing louder, then Sparrow #2 began singing a variant of #1’s song.  They went back to trees on either side of the pathway, again singing back and forth. The songs were so close now that the second began before the first was completed.  Next, #1 flew across the path into the tree where #2 was singing and both sang from this close proximity. 

#2 flew back to the ground, appearing once again to feed, and #1 immediately flew down to where #2 was located. They continued to sing, but softly. Finally, #2 flew farther away and #1 sang this song from his preferred tree.  


I returned an hour later. They were once again singing back and forth from their trees on either side of the path, singing the same songs as when I first met then. (Sparrow #1’s song is the one with the long trill followed by the ascending tritone.)  Earlier, I had observed wing fluttering by one of them as if this were a courtship ritual.  Now, one appeared to try to mount the other!  Just exactly what was going on here?  

As before, they would come together on the ground, then move up into the small trees.  Both birds sang close together, then flew farther apart.  This seemed to be the same pair of songs they had sung during the first close confrontation. Then #1 changed his song, and #2 changed his to something similar.  They sang the new set of songs back and forth as they had earlier.  Here are the songs from the close encounter followed by the pair of songs they were singing as I left.

I left still puzzled about what I had seen and heard.  How could it sound like a territorial confrontation but look like courtship?

When we returned home, I went straight to the volume 1 of the Stokes Guide to Bird Behavior and looked up what Donald Stokes wrote about Song Sparrows.  “As the season progresses and more males arrive, look for territorial skirmishes – new males challenging established ones for favored areas.  These take place with an unusual display, where one of the birds puffs out his feathers, possibly raises one or both wings, and sings. The contour feathers are fluffed, and one or both wings are raised and possibly vibrated.”  

This is what looked like courtship behavior to me, as when a female imitates a fledgling!
“The territory holder moves along close to the ground, his body feathers fluffed, singing softly and possible lowering and raising one wing.  The intruder follows him silently,  After a while, a short chase or fight may occur, after which both birds move to safe areas and sing loudly.  Often both birds will appear to be feeding throughout the interaction.” 

That was exactly what I saw and heard!

“The challenges to a territory may continue for an hour or more”

I suspected that Song Sparrow #1 may have been the original holder of the territory. He never backed down and never flew farther away.  
I returned on April 4th to see if I could determine the outcome.  Only one Song Sparrow was there, and his picture is below.  I recorded two songs of his that afternoon – and both were those of Song Sparrow #1.


1 comment:

  1. I love song sparrows and I love the Stokes behavior guides!