Burke Museum - 2

Lat:47.66063861939029, Lon:-122.31028240171611
Day, 2012
4/23/12
1:30-3:30

Also at the Burke Museum, we learned about Hermit and Townsend warblers. We saw probably about 50 of these small black and yellow birds in the Burke collection. In comparison, Townsend warblers have more yellow on their bodies and look more striped with black, white, and yellow; whereas Hermit warblers have mainly yellow heads with black bodies and white/grey chests. However, as we saw in the collections, there are many hybrid variations of each of these warblers. We looked at many boxes of warblers with Townsends at one end, a whole bunch of hybrids in the middle, and a Hermit at the other end. The hybrids of these birds were very interesting but apparently they aren't seen in field guides so that might get a little confusing.

Interestingly, Townsend warblers are very aggressive towards the Hermit warblers. This forces the Hermit warblers to move southward, away from the Townsends. However, the Townsends eventually catch up and force the Hermits even further south. Subsequently, this also moves the "hybrid zone" in between them south as well. From what Josh explained, this zone moves about 1km south every year. While this "competitive exclusion" is moving the whole warbler system south, climate change is moving it north. Therefore, the whole question with these warblers is what's going to happen when these two forces decrease the size of the hybrid zone or wipe it out all together. I wonder if the Townsend warblers' aggression will reduce the Hermit warbler population or if these Hermit warblers will become extinct as a consequence.

Another very interesting thing about these warblers has to do with their DNA composition. While the DNA between Hermit warblers and Townsend warblers is different, each bird (Townsend or Hermit) can have the DNA of the other. We looked at a map and there were zones with orange and blue dots of varying sizes. The size of the orange dots represented the percentage of Townsend warbler individuals with Townsends DNA; and the size of the blue dots represented the percentage of Hermit warbler individuals with Hermit DNA. This is intriguing because I had never heard of an individual species that can essentially still be that individual while having some of the DNA of another individual.

Species List:
Hermit warbler
Townsend warbler

Posted on May 22, 2012 08:00 PM by lisad22