Tuesday, October 9, 2012

Tuesday's Results: Tree Swallows Galore!

This morning's cooler temperature and 12 mph winds were less than ideal for banding birds.  We waited an extra 30 minutes before opening nets so that the birds were not exposed to the cooler temps and the wind any longer than they needed to be.  We also only open the nets that were the most sheltered from the wind.  Because the wind was from the north all of the nets along the Kiawah River were not opened as these nets can be highly affected by north winds.  Combine that with a temperature of 55 degrees, and the smaller birds have the potential to become highly stressed.  Bird safety is our number 1 priority at KIBS, so we took no chances.  


Despite the wind and having 7 less nets opened for a majority of the day, we banded 84 new birds and had 16 recaptures of 19 different species.  Highlights of the day include Blackpoll Warbler (2), Cape May Warbler (2), and Tree Swallow (4; the first banding records for this species at KIBS!).  

Blackpoll Warbler (hatch-year, male)

Cape May Warbler (hatch-year, male)

Around 9:00 am hundreds of Tree Swallows descended onto KIBS like a scene out the Alfred Hitchcock movie - The Birds.  We watched them get closer and closer and soon they were practically right on top of us.  We watched in amazement as all of these birds attempted to land on a small group of wax myrtles right next to one of our CLOSED mist nets.  Just as weight of the birds caused the wax myrtle branches to bend towards the ground, they all took off into the sky only to repeat this process over and over again.   I have witnessed this behavior several times over the years in the fall and the winter.  Swallows are insectivores, but they will also feed on berries, especially those of the wax myrtle.  Tree Swallows are one of only a handful of species that are able to digest the waxy cuticle of the wax myrtle fruit.  Their ability to shift their diet to berries during the fall and winter may explain why Tree Swallows winter farther north than any other North American swallow.  Although we have seen large groups of swallows already this fall, this is the first time we have seen this type of behavior this season.  I suspect the overcast conditions coupled with the cooler temperatures and wind prevented the insects from becoming active, in turn the Tree Swallows took advantage of the large crop wax myrtle berries.

                                                             Video by William Oakley

In between one of these Tree Swallow feasting events, DeeAnne and I snuck over to the mist net and opened it up.  Just as we got the net opened, 4 Tree Swallow flew in and as we were extracting them from the net we noticed that one of the birds still had a couple of wax myrtle berries in its bill.  I am sort of glad the net was not opened before the swarm of swallows arrive.  If it had been, no telling how many birds would have been captured. 

Tree Swallow


5 White-eyed Vireo

5 Red-eyed Vireo

4 Tree Swallow

1 Swainson's Thrush

15 Gray Catbird

1 Brown Thrasher

2 Northern Parula

1 Magnolia Warbler

2 Cape May Warbler

3 Black-throated Blue Warbler

1 Palm Warbler (Western)

2 Blackpoll Warbler

1 Black-and-White Warbler

7 American Redstart

26 Common Yellowthroat

8 Indigo Bunting



1 Downy Woodpecker

2 Carolina Chickadee

5 Gray Catbird

1 Brown Thrasher

6 Common Yellowthroat

1 Painted Bunting



# of Banded Birds:  84

# of Recaptures:  16

# of Species:  19

Effort:  72.5 net-hours

Capture Rate:  137.9 birds/100 net-hours

# of Nets:  13 (3 of which were opened late)


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