pension333: Today's mystery bird for you to identify

This Ethiopian mystery bird is part of a group of birds that share a particular life history trait that affects their morphology

Mystery Bird photographed at Lake Zway, one of the freshwater Rift Valley lakes of Ethiopia (Africa). [I will identify this bird in 49 or so hours]

Image: Dan Logen, 30 January 2011 (with permission, for GrrlScientist/Guardian use only) [velociraptorise].
D300s, 600 mm lens, ISO 640, 1.4 extender, 1/2500 sec., f/6/3

Question: This Ethiopian mystery bird is part of a group of birds that share a particular life history trait that affects their morphology. What trait is that and how is the morphology of these birds affected? Can you name this bird's taxonomic family and species?

The Game:

1. This is intended to be a learning experience where together we learn a few things about birds and about the process of identifying them (and maybe about ourselves, too).
2. Each mystery bird is usually accompanied by a question or two. These questions can be useful for identifying the pictured species, but may instead be used to illustrate an interesting aspect of avian biology, behaviour or evolution, or to generate conversation on other topics, such as conservation or ethics.
3. Thoughtful comments will add to everyone's enjoyment, and will keep the suspense going until the next teaser is published. Interesting snippets may add to the knowledge of all.
4. Each bird species will be demystified approximately 49 hours after publication.

The Rules:

1. Keep in mind that people live in zillions of different time zones, and some people are following on their smart phones. So let everyone play the game. Don't spoil it for everyone else by blurting out the bird's common or scientific names in the first 24 to 36 hours.
2. If you know the mystery bird's identity, answer the accompanying questions and provide subtle ID hints that may serve as helpful clues for less experienced players. Keep in mind that some hints, such as puns and anagrams, may read like "inside jokes" and thus, may discourage others from participating.
3. Describe the key field marks that distinguish this species from any similar ones.
4. Comments that spoil others' enjoyment may be deleted.

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You are invited to review all of the daily mystery birds by going to their dedicated graphic index page.

If you have bird images, video or audio files that you'd like to share with a large and (mostly) appreciative international audience here at the Guardian, feel free to contact me to learn more.

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Source: http://www.guardian.co.uk/science/grrlscientist/2012/aug/18/6

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