It seems like a very long time since I last went actually birding - my excuses include moving house, a series of trips to the Middle East where the temperature was hotter than Satan’s underpants and I stayed in the hotel rather than fry, general apathy etc etc - but just two days ago I spent an excellent few hours with my old friend Jack Cole at the Don Edwards San Francisco Bay National Wildlife Refuge (which is more commonly known - for reasons obvious to anyone who has ever had to either write or say ‘Don Edwards San Francisco Bay National Wildlife Refuge’ - as Alviso).

Alviso spans about 30,000 acres/12140 hectares of open bay, salt pond, salt marsh, mudflat, upland and vernal pool habitats in south San Francisco Bay. Located along the Pacific Flyway, the Refuge hosts over 280 species of birds each year and large numbers of shorebirds and waterfowl stop off to refuel during spring and fall migration. In addition to its seasonal visitors the Refuge provides critical habitat to resident species like the endangered California Clapper Rail Rallus longirostris flavipes and Salt Marsh Harvest Mouse (neither of which I’ve seen on my three or four visits to Alviso I should point out for anyone wanting to see either species).

Don Edwards San Francisco Bay National Wildlife Refuge, July 2009

This time of year the notorious Californian coastal fog can be a huge problem (incidentally does anyone else find a mile high fog bank silently rising up over an entire city really freaky?). Under a monochrome fog bank photography and birding is a little difficult, but it had burnt off by about 11:00 and birding at Alviso is always interesting anyway - for a Brit anyway, I get the impression that local birders find the place a little ’samey’ in July - and by the time we left around 13:00 we’d seen some pretty good birds.

We missed an on-off Black Tern Chlidonias (niger) surinamensis that has been seen in the area over the last few weeks, and a Ruff Philomax pugnax that had been found two days before, but early passage shorebirds (including high numbers of Wilson’s Phalaropes Phalaropus tricolor and far smaller numbers of Red-necked Phalaropes Phalaropus lobatus on the channel running alongside the New Chicago Marsh), masses of breeding Forster’s Terns Sterna forsteri on the four purpose built islands in Pond A16, and showy Savannah Sparrows Passerculus sandwichensis hopping about in the pickleweed (and some sunshine - HURRAH) made for a great few hours.

Mixed shorebirds - mainly Long-billed Dowitchers Limnodromus scolopaceus,
Greater Yellowlegs Tringa melanoleuca, and Black-necked Stilts Himantopus mexicanus

Wilson’s Phalaropes Phalaropus tricolor with
Red-necked Phalarope Phalaropus lobatus

Adult non-breeding Wilson’s Phalaropes P. tricolor

Mixed flocks of Wilson’s P. tricolor and Red-necked Phalaropes P. Lobatus

 

Worn post-breeding Least Sandpipers Calidris minutilla

 

Black-necked Stilts Himantopus mexicanus

I’m not sure how many pairs of Terns breed at Alviso, but pretty much most of what you can hear at the Refuge is the rasping calls of adult and young Forster’s Terns. Most overseas birders won’t get to see Forster’s Terns in juvenile plumage (I certainly hadn’t seen them before) so hopefully the two images of a young bird below will be of interest…

Juvenile Forster’s Tern Sterna forsteri

As I mentioned earlier Alviso is also an excellent place to see Savannah Sparrows Passerculus sandwichensis. I’m not sure which race occurs here, and given the clinal and/or mobile nature of the species’ populations I wonder whether it’s possible to be certain anyway (I do know they’re not the very localised beldingi which occurs further south), but they’re typically incautious and often allow quite a close approach (if that approach is slow and nonthreatening anyway).

Photos of Savannah Sparrows are all over the web so these below aren’t especially noteworthy, but both Jack and I would be very interested to know whether any sharp-eyed field biologist can identify the prey item the sparrow in the last two photos is carrying. Neither of us could even be sure at the time - and it was quite close as you can see from the images - whether it was ‘animal or vegetable’. Any comments will be welcome, so thanks in advance…

Savannah Sparrows Passerculus sandwichensis - any ideas on the prey item?
Lower image © Jack Cole

All good stuff really, but the highlight of this short visit was an unexpected fly-over. Not a vagrant but a normally rather secretive species that Jack certainly didn’t expect to see flying over Pond A16 at about 100′ straight towards us both as we stood on the central levee…an American Bittern Botaurus lentiginosus!

American Bittern Botaurus lentiginosus

Once the Bittern had flown over and we realised we weren’t likely to find either the Black Tern or the Ruff (both of which would be typical autumn fare on a UK wetland in early autumn incidentally) Jack and I decided to call it a day. We did spend a few minutes looking for Alviso’s resident Collared Doves Strepopelia decaocto (again not exactly a high priority bird for me - or Jack come to that), one of which was perched on the TV aerial of one of the houses bordering the Refuge, before heading home.

As this post shows it wasn’t quite a Red Letter day at Alviso, but very enjoyable nonetheless. You’ll need transport to get out to the Refuge but once you get there you won’t regret it IMHO - I’d hope that Jack and I get a chance to go back anyway. It won’t be soon, but I’ll blog about when I do…

All photographs copyright Charlie Moores 2009