USA 2023 - Birding on Alcatraz Island, San Francisco

Thursday 13 April 2023

Birdwatching probably isn't the first thing that comes to mind when you think of Alactraz. I doubt whether many - or indeed any - of the tourists that flock to this famous prison have come to mainly to look at the seabirds. But, as a predator-free island in the middle of San Francisco Bay, it's hardly surprising that birds have chosen to nest here. The photo above shows one of the main concentrations of Brandt's Cormorants on an old jetty next to the prison yard.

In fact, the island is named after birds - although, typically, the explorer responsible (one Juan Manuel de Ayala in 1775) got it wrong. Alcatraz is Spanish for Gannet, which is a bird that you definitely won't see here. Various online sources tie themselves in knots trying to explain this: one possibility is that alcatraz is an archaic Spanish name for a pelican (this is now pelícano). There are pelicans in the San Francisco area, but none are currently nesting on Alcatraz. More likely, our explorer simply didn't know his birds.

Alcatraz island

The prison is clearly the main attraction, and the self-guided tour is grim but fascinating. I'd been before, and wanted to concentrate on the island's natural history. And the excitement starts even before you board the ferry. Some Pigeon Guillemots (below) flew in and started diving for fish just off Pier 33, which is where the boat departs from San Francisco's Fisherman's Wharf. Looking very like Black Guillemots, these have a black bar projecting into the white wing patch.

Pigeon Guillemot - Pier 33, San Francisco. (Note the dark bar through the white wing patch.)

Pigeon Guillemots - Pier 33, San Francisco

Once out into the Bay, we could see flying seabirds, including a Pelagic Cormorant, showing its distinctive white patch, and several Common Murres (the same species as Common Guillemot on 'our' side of the Atlantic). It was a bit unsettling to see this mix of familiar and new species in the same habitat.

As the boat approached Alcatraz, we were hit by that overpowering smell of guano that is common to seabird islands the world over, but which for me only ever says one thing: the Farnes! We were moving quickly towards the landing stage, which gave very little time to scan the seaweed-covered rocks (below) as we passed by. 

Approaching the jetty on Alcatraz

Western Gulls and Brandt's Cormorants were the most conspicuous birds here, but I was pleased to pick out three Black Turnstones just above the waterline. Here's a terrible record photo:

Black Turnstones (record) - there are two below the gull's feet and one more bottom right.

Black Turnstones winter on this coast, heading north to Alaska to breed. eBird suggests that they are absent from Alcatraz in May and June, so we were lucky to catch them.  Mind you, Black Oystercatchers are there all year round (with two pairs this year), but I failed to spot any – and it’s not as if Oystercatchers are inconspicuous, either. One for my next West Coast trip, I hope

At the jetty, I was interested to see the year's waterbird count data (below) – also reminiscent of a similar notice-board on Inner Farne – although it hadn’t been updated for a week (it’s dated 6 April). The right-hand column has the 2022 data. We had arrived early in the season, and it looked like numbers of breeding birds on the island would carry on increasing. I was keen to get exploring, but first we sped up the hill to do the tour of the cellhouse, getting there before the rest of the boat’s passengers who weren’t moving quickly. If you haven't been on the self-guided tour, it's certainly worth doing.

Alcatraz bird count April 2023 (2022 data on the right)

The jailhouse tour finished in the exercise yard: I popped back into the cellblock to return our headsets and we then exited the yard though a side gate. This led to a steep flight of steps, which led to a path looking over a magnificent colony of Brandt’s Cormorants (see below and also the photo at the start of this post). Nest building was in progress and most – but not all – birds were sitting on a small patch of seaweed; some piles were obviously green and recently-foraged. A few of the breeding birds were showing vibrant cobalt blue throat skins.

Brandt's Cormorants (mostly) - Alcatraz CA

Brandt's Cormorants (with passing Western Gull) - Alcatraz CA

Brandt's Cormorant - Alactraz CA - detail

What the photos can’t convey is the all-pervasive ammonia-laden smell; I doubt whether large seabird colonies were allowed or encouraged during the island’s prison years. But now the birds have regained control - at least of some parts of the island.

Just offshore were two more Pigeon Guillemots (below), showing off their red legs nicely. 

Pigeon Guillemots - Alcatraz, CA

Rather than returning through the cell block, we took a path through the gardens (being carefully tended by volunteers), where a Song Sparrow (below) perched up nicely. It’s common on both west and east coasts of the US. North American sparrows can be confusing, but the russet-brown crown and eye stripe, with a streaked breast, made this one reassuringly straightforward to identify.

Song Sparrow - Alcatraz CA

As well as volunteer gardeners, there was a volunteer birder on hand who knew his stuff. He was particularly interested in the herons that nest on the island, the most obvious of which was a nearby Snowy Egret (below), although this one looked like it was roosting rather than nesting. 

Snowy Egret - Alcatraz, CA

Much less obvious, in fact I would have missed it had the ranger not pointed it out, was a Black-crowned Night Heron (record photo below). These were building nests (there were 125 nests of this species in 2022), that were well-concealed in the verdant bushes.

Black-crowned Night Heron (record photo) - Alcatraz CA

‘Have you seen the Great Blue Herons?’ the ranger asked. ‘Err … no,’ was my response.  It turned out that we'd walked right underneath them when we had first arrived on the island. They were in a large, and rather incongruous, eucalyptus tree on the other side of the cell block. The information board said that there were 7 nests, with 2 incubating eggs. Not all of the nests looked occupied, but I was able to pick out a couple of birds. This adult Great Blue Heron (below) was sitting on its nest, so very likely incubating.

Great Blue Heron on nest - Alcatraz, CA

And, with that, we joined a long queue for the boat back to Pier 33. It was farewell to Alcatraz, and also the end of a memorable holiday to West Coast USA. I would love to return ...