Wednesday, August 7, 2013

Andromorph White-faced Meadowhawk









White-faced Meadowhawks are abundant dragonflies around Northfield. With their white faces, they are relatively easy to identify. The first photo is of a female, the second is a male. On 1 August 2013, I took the third photo. In the field, I assumed I was seeing a male White-faced Meadowhawk. When I got home, however, I noticed that the face was actually red-tinged. Scott King, my dragonfly expert, responded that the odonate is indeed a White-faced Meadowhawk, but not a male—rather a rare andromorph female. Other dragonflies are often more prone to have andromorphs—but the trait is uncommon in White-faced Meadowhawks.

Scientists do not understand the factors that cause andromorphs. Looking like a male apparently keeps her from constant harassment from males interested in mating. Andromorphs may be more aggressive than dull females, and they often remain less hidden. Males often retreat from andromorphs, thus, compared with other females, food resources may be greater for the andromorph. She just has to convince one mate that she is, indeed, a female. The disadvantage to the andromorph, however, may be that, being brightly colored, she is easier for predators to see.

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