Sunday, August 17, 2014

Heermann's Gull - Juveniles Missing

A recent posting to a birding group reported that no juvenile Heermann's Gull (Larus heermanni) were being seen on the Calif. West Coast.  (photo, adult Heermann's Gull in winter plumage)  Heermann's breed in the early spring in large colonies on islands off the West Coast of Mexico.  After the breeding season they move north along the pacific coast to Southern British Columbia.  Beginning in mid-summer large flocks of the Heermann's can be found on the Morro Strand State Beach.

Yesterday I decided to check out the Heermann's flocks to see if I could find a juvenile or the next stages of development, a 1st winter or a 1st summer.  I do enjoy a challenge. 
At first I had a problem with the flocks having to relocate due to the number of people on the beach and children who enjoy chasing birds.  Finally the flocks settled down and I was able to have a prolonged look.  Normally, younger Heermann's are scattered throughout the flock  (below photo of a 1st winter or 1st summer).  I could find only six 1st winter/1st summer and no juveniles.  The above photo represents about 1/10 of one flock. 
My observations prompted the thought, "Why a lack of youngsters?"  Perhaps environmental conditions, such as warmer water temps, algal blooms, and acidification are having an adverse effect on the ocean food chain.  What ever the reason, there were fewer young Heermann's Gull than in prior years.
On to the other birds.  To my delight, there was a variety of shore birds, Semipalmated Plover (a favorite), Long-billed Curlew, Whimbrel, Caspian and Elegant Tern, and Ring-billed Gull.  Off shore were several Eared Grebe and Surf Scoter.  Most enjoyable was watching several Marbled Godwit feeding on tiny flies on the sand that had been churned up by horse hoofs. (above photo)   

If you look at the larger image of the Godwit, you will see a distant relative of the jellyfish, Velella velella, the little bluish, transparent things in the background.   They are free-floating hydrozoans that live on the surface of the open ocean.  At certain times of year the wind propels them to shore.  At the present time there are millions of Velella velella on central coast beaches.  Happy birding!



  1. Glad you had that challenge accomplished Joyce !
    You really know very well about birds !

  2. Hi lina. I really know very little about gulls. They mature slowly and each stage of development looks a little different