Mystery Bird photographed at Golden Gate Park, San Francisco, CA, USA. Image: Joseph Kennedy, 21 December 2010.

Here’s a fun challenge from the UK!  The bird is in Golden Gate Park: “This beautiful North American mystery bird is quite special when compared to its brothers and sisters — how?

Complaints about yesterday’s mystery bird being ‘too easy’ are being met with a much more difficult mystery bird today! This beautiful North American mystery bird is rather special when compared to its brothers and sisters. Can you name the species and tell me what is so special about this individual?

About the Daily Mystery Bird:

The Rules:

1. Keep in mind that people live in 24 different time zones, and some people are following on their iPhones. So let everyone play the game. Don’t spoil it for everyone else by identifying the bird in the first 24 to 36 hours.

2. If you know the bird’s identity, provide subtle hints to let others know that you know. Your hints may be helpful as small clues to less experienced players.

3. Describe the key field marks that distinguish this species from any similar ones.

4. Comments that spoil others’ enjoyment may be deleted.

The Game:

1. This is meant 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 may be intended 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 48 hours after publication.

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

via Today’s mystery bird for you to identify | Science | guardian.co.uk.