2017-06-01 Nesting at Border Field

Western Snowy Plover

I drove down to Border Field this morning and met with the biology team surveying the California Least Terns (endangered) and Western Snowy Plovers (threatened). Both species struggle with habitat issues. The coastal beaches and wetlands they require for nesting have been decimated by human development.

I’m not sure if I made any worthwhile captures, but I enjoyed the time spent with the folks on the team. There were two members today I’d not previously spent any field time with. One was Eddie, a US Fish & Wildlife biologist recently added to the staff stationed at the South San Diego Bay NWR. His previous assignment was in Ventura County monitoring the California Condor reintroduction program. I enjoyed hearing him tell stories about his experiences there, and I learned how they’ve been treating birds with lead poisoning. As I understand, the birds are captured and given chelation treatments until the lead in their system is reduced to a safe level.

The second new member I met today was a nice young lady, Bronti, a biologist with state parks, who I believe was in her first season with the team here. Robert and Lea, whom I’ve worked with on numerous occasions over the years, are always a hoot to hang with. I always run the risk of learning something interesting about nature when I get to spend time with them.

As a photographer this day, I struggled for contrast. Overcast with white skies, and white sands and the white birds, does not lend to striking imagery. As a lover of nature, there were many positives. Unlike the Saltworks at the southern limits of San Diego Bay, where Western Least Terns breed in miniscule numbers, there were quite a few birds here. The nesting takes place on the sands away from the beach. Only a string line on flimsy poles separates the protected nesting area from the public beach. Tracks of bicycles and of dogs dragging leashes through the nesting area reveal how inadequate this barrier is and how selfish and inconsiderate the human species can be.

Careless humans are not the only threat the birds nesting here. Tracks of larger birds such as gulls, herons and egrets can be found in these sands. Coyotes and feral cats and dogs are a problem. Threats from airborne predators exist in the form of Peregrine Falcons, Northern Harriers and Gull-Billed Terns. These will prey on the young of the birds nesting here too. US Fish & Wildlife goes to considerable effort and expense to mitigate these problems, but the staff assigned to this duty have large tracts to protect, scattered across miles of the city and county. They can not be in all places at once nor can they be on duty 24 hours a day.

Following our day in the field, Robert Patton sent me the following report on the status of the nesting birds here.

Tijuana Estuary North of the river

14 Western Snowy Plover, include at least 4 unbanded
12 total nests, 6 active, 0 new, 1 nest w at least 2 eggs depredated with harrier tracks
1 chick seen, but 1-2 additional broods possibly in area; 2 fledglings of 1 brood
90+ California Least Tern
109 total nests, up to 91-92 active, 17 new, 12 hatched, 1 uncertain outcome
24 chicks of 15 broods seen, possibly up to 3 additional broods not seen

All birds flushed as female harrier coursed S-N over rivermouth area; California Least Terns mobbed gull over; egret or night-heron tracks in nest area

South of the river at Border Field SP

9-10 Western Snowy Plover, incl at least 6 unbanded
14 total nests, 3 active, 0 new
40+ California Least Tern
47 total nests, up to 43-46 active, 2 new

California Least Terns up as pair of harriers hunting dunes & marsh S trail; coyote tracks in nest area N trail

Tracks of person walking bicycle in nest area length of nest area N of trail; S of trail repaired twine broken in 5 places, footprints into nest area

Images Below:

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