Monday, May 28, 2012

Red Knots, Skimmers and Oystercatchers

On my trip to Cape May for the Maygration Birding Festival I had hoped to see many warblers, but the timing was off. Because of the warm winter migration was early. By the time we started looking most males had established their local territories and had stopped singing, making them hard to find. 


However there were large numbers of shorebirds and seabirds. I was thrilled to see Red Knots, those fabled long distance travelers who on their journey from the southern tip of South America to the arctic tundra descend in huge numbers on the shores of the Delaware bay, their only stopover, where they fatten up on horseshoe crab eggs to replenish their depleted energy stores. In the last decades, though, the massive harvest of horseshoe crabs for bait has threatened the survival of the birds. A moratorium is now in place. 



In the hundreds of photos I took of distant shorebirds (distant because the beaches were closed for nesting)http://www.birdcapemay.org/spring.shtml I found only three Red Knots, although I briefly saw a larger flock which landed  but took off again right away. They are one of the largest sandpipers. They get their name from the red chest in breeding plumage.



Several years ago I watched  a program on PBS on horseshoe crab being harvested for their blood. It showed crabs in a large pharmaceutical lab being lined up at blood letting machinery like so many widgets. Fortunately many of the crabs survive the process and are released back into the sea.


Wikipedia.org: "Unlike mammals, horseshoe crabs do not have hemoglobin in their blood, but instead use hemocyanin to carry oxygen. Because of the copper present in hemocyanin, their blood is blue. Their blood contains amebocytes, which play a role similar to white blood cells for vertebrates in defending the organism against pathogens. Amebocytes from the blood of L. polyphemus are used to make Limulus amebocyte lysate, which is used for the detection of bacterial endotoxins.
Harvesting horseshoe crab blood involves collecting and bleeding the animals, and then releasing them back into the sea. Most of the animals survive the process; mortality is correlated with both the amount of blood extracted from an individual animal, and the stress experienced during handling and transportation. Estimates of mortality rates following blood harvesting vary from 3% to 15%."


Black Skimmers, so flamboyant in their appearance are another species that I wanted to catch on camera. Flamboyant in their appearance and habits. As their name implies with their peculiarly shaped beaks, hinged larger lower beak, they skim the surface of the water scooping up and snapping down on whatever prey comes their way. Here is a colorful description taken from BNA: The buoyant flight of this bird, coupled with its dog-like barks, prompted R. C. Murphy (1936) to describe Black Skimmers as “unworldly…aerial beagles hot on the scent of aerial rabbits.” I missed hearing that bark :-)






The American Oystercatcher was another bird on my list to see. I am familiar with the Eurasian species. They are similar but not the same.

Their beak is laterally flattened to squeeze into a tiny opening of a bivalve and cut the adductor muscle. If the clam is closed they use their beak to hammer a hole into the shell. 



Courting pair in a piping display walking along the beach, being briefly swallowed by a wave and reemerging unruffled.





 Piping display



On nest

 

The birds are monogamous and stay together as long as they live. Unlike sandpipers, whose feeding habits are hard-wired and who can make it on their own, the fledglings stay with their parents for a couple of months to learn to open clams and other bivalves. Below, a chick running away to hide. 





A pair performing an aerial piping ceremony. It is not uncommon for outsiders to join in.




More from Cape May next week. Happy Birding!

21 comments:

  1. Hi Hilke

    I enjoyed your post the Skimmer shots were great and the information about the Oystercatcher was very interesting. I have never seen a young one and I did not realize they spent so much time learning. I am glad they stopped harvesting the Horseshoe crabs they have been around so long it would be terrible to wipe them out for bait.

    Regards
    Guy

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  2. Great post, Hilke! I love see all the shorebirds this time of year. The skimmers and oystercatchers are cool looking birds.

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  3. Great work with the shorebirds Hilke.

    Warblers never make it easy, but at least shorebirds let you go birding at the beach!

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  4. Great shore visit Hilke!! Boom & Gary of the Vermilon River, Canada.

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  5. ...I really enjoyed this post, Hilke! Skimmers and Oystercatchers are always a favorite of mine. I only get to see them when I go to the beach for vacation. A read about Red Knots a few years ago and was amazed at their travels. I had no idea all that was going on with the horseshoe crabs.

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  6. Fun! Love the Oystercatcher photos!

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  7. This was a wonderfully informative post and the pictures are beautiful. I am a new follower and look forward to your future posts. Thank you to teaching me something new ...

    Andrea @ From The Sol

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    1. Thank you, Andrea. I hope to keep surprising my readers, and myself of course, with new info. That makes blogging for me interesting.

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  8. A great series of photos - I especially like the Oystercatcher photos.

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  9. I'm happy to see you and your birds again!! Wonderful pictures and great information (I remember that part of your posts from last year).... I saw my first Black Skimmer this season here in Florida, but didn't see it actually skimming (I referred to that post this week)....so to watch it fly is one of my (many) goals for next season here. (We'll be in Colorado and Oregon for the summer and so no skimmers for us).

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  10. Great work! I love the picture of 'piping display'.

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  11. Excellent post Hilke! I saw my first Red knot this spring. It certainly is a remarkable flight they take, sort of hard to believe looking at them that they are capable of such an achievement. Fascinating stuff indeed!

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  12. Hi there Hilke. A great post with interesting information. I was particularly interested in your Oystercatchers as I managed to capture my first Pied Oystercatchers last week (I plan to post them next week).
    Isn't it a treat when you manage to capture flight shots worthy of posting. see you next week.

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    1. Thanks, Liz! I am looking forward to see your Pied Oystercatcher!

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  13. Sorry you saw so few Red Knots, Hilke. Great photos of the skimmers and oystercatchers!

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    1. Thanks, Ken! I am even hesitant to call it "seeing" since I only discovered them on my photos after the fact :-)

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  14. Great post love the photos and all the information too. I am bookmarking your blog - love the name by the way. Thanks.

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  15. Interesting info about crabs. Great pictures with the post.

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  16. Enjoyed the pics...especially the Piping display...and the info.

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  17. Wonderful post filled fantastic photographs and interesting information! How lucky you are to see all these beautiful shorebirds.

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  18. A fascinating post about these wonderful birds Hilke.. I have never seen a wave break over birds before.

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