Sunday 2 April 2023 (cont'd)
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| Acorn Woodpecker - Elkhorn Slough CA |
This is the fifth, and final, post from a memorably fulfilling day of watching birds and marine mammals on California's Monterey Bay. It is the third about birds - the first two are here and here.
Just up the river from the fishing (and whale-watching) port of Moss Landing is Elkhorn Slough. The reserve's full title is a bit of a mouthful - the Elkhorn Slough National Estuarine Research Reserve. The Elkhorn Slough Foundation's website provides much more information about the site - the link is here (opens in a separate window). The protected area at Elkhorn Slough includes a salt marsh, the estuary, grassland and oak woodland, so there's a good range of habitats to explore along a network of trails.
It was now mid-afternoon. We parked at the visitor centre and, after a quick chat with a ranger, decided that there was enough time to walk the two mile South Marsh Loop. A Northern Harrier floated over as we followed the trail down the hill and headed for the mudflats.
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| Willet - Elkhorn Slough CA |
This Willet (above) was foraging near to the trail, a common wader (shorebird) of the Americas. In the western USA it mainly winters on the coast and breeds inland. My only previous encounter with the species was on Trinidad in the Caribbean, where a lone bird was over-wintering in Trindad's Caroni Swamp. (I have to admit that, at the time, I was more excited by the spectacular Scarlet Ibis roost.)
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| Long-billed Curlew - Elkhorn Slough CA |
My first Long-billed Curlew (above) was also probing the mud next to the boardwalk. Like most curlews, Long-billeds are declining in numbers, although the species is still classed ‘least concern’ by the IUCN. The bill of this individual is disproportionately long, but not quite as dramatic as the illustration in Sibley, which led me to wonder at first whether this might be a Whimbrel. It’s clearly not, of course: the bill of the Whimbrel is markedly more stubby, and Whimbrels also have a light stripe through their dark crown. This does not. Also note the buff tinge on the belly.
I like curlews, particularly ‘our’ (Eurasian) species, the cry of which transports me to the rocky coasts and open moorlands of Scotland and the north of England. It is tragic that so many curlew species are endangered – or, indeed, extinct. Worldwide, eight species of curlew are identified in the HBW/Birdlife International Checklist. In terms of the IUCN Red List, only three are considered to be at the lowest conservation threat level - 'least concern’ - (Whimbrel, Long-billed and Little), while two (Eurasian and Bristle-thighed) are ‘near threatened’ and one is ‘endangered’ (Far Eastern). Even worse, Slender-billed Curlew is ‘critically endangered’ and Eskimo Curlew is ‘critical, probably extinct’. Bearing in mind that the last confirmed sighting of an Eskimo Curlew was in 1963, even that assessment looks unduly optimistic. But I suppose that you never know.
Together with the godwits, curlews seem to be particularly prone to problems, perhaps more so than any other group of waders. I'm not entirely sure why. An impressive analysis of the threats facing the group (Pearce-Higgins et al. 2017) doesn't provide a definitive answer to that question, but it does point the finger at some possible factors. First, some curlew species have (or had) fairly restricted breeding ranges. Second, they have relatively large body sizes and low breeding rates, and are therefore reliant on high annual survival rates. As a result, they are especially vulnerable to land use changes that have reduced the availability of suitable habitat. This has been a particular problem along some migration routes, notably the East Asian - Australian flyway. Graeme Appleton has written a good blog on this in his Wader Tales series (link here - opens in new window).
Although Long-billed Curlews are migratory, they don't travel as far as some of their more endangered cousins. As well as west coast USA, they also overwinter in Mexico; breeding takes place inland in western North America.
According to the IUCN Red List website (link here - opens in new window) the main threat facing the Long-billed Curlew is the conversion of grassland into agriculture, with sea level rise being a longer-term concern due to loss of coastal wintering habitat. Protecting sites like Elkhorn Slough is therefore a real priority.
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| California Poppy - Elkhorn Slough CA |
A grassy slope above the mudflats was dotted with California Poppies Eschscholzia californica (above). It’s the state flower of California, but is not endemic to the state; its range extends from Washington (state) down to Baja California, as well as the south-western states of Nevada, Arizona and New Mexico. California Poppies can flower in large numbers. A few days later (near Mojave CA) we were to see hills tinted orange with their blooms.
Crossing a footbridge over a side creek, we followed the trail towards the woodlands. Our route passed between two ponds. On the first, a pair of Cinnamon Teal (below) looked marvellous, the male shining in the afternoon sunshine like a well varnished garden fence. These ducks are found from western Canada right down to Patagonia, although they seem to avoid Brazil for some reason.
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| Cinnamon Teal pair - Elkhorn Slough CA |
This was a new species for me, as was a Canvasback on the other pond, which was accompanied by several Buffleheads and a Lesser Scaup. Canvasback is one of two orange-headed American ducks that at first sight look similar to the Common Pochard of Eurasia, the other being the Redhead - which I was to encounter a few days later in Nevada. Of the two, Canvasbacks are bigger, and have black (not blue-grey) bills with a ‘sweeping’ bill profile that continues its sloping forehead. My record photo is too poor to share here!
I was so excited about the ducks that, at first, I failed to spot what turned out to be my favourite bird of the holiday - an Acorn Woodpecker (below - and photo at the head of this blog post), another first for me.
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| Acorn Woodpecker - Elkhorn Slough CA |
In all, we saw four Acorn Woodpeckers, climbing on and flying around some dead trees where the tidal water lapped up to the woodland edge. With their striking head pattern – you can't avoid saying ‘clown-like’ – Acorn Woodpeckers have a real ‘wow’ factor. This is a male, with an all-red crown. They occur in oakwoods in the western USA and Mexico, as well as parts of Central America down to Colombia. As we saw at Elkhorn Slough, Acorn Woodpeckers store many (many!) acorns by jamming them into holes in tree trunks. They are territorial, defending these stores (‘granaries’) against squirrels and jays – as well as other Acorn Woodpeckers.
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| Acorn Woodpecker 'granary' - Elkhorn Slough CA |
We walked into the wood. The dominant species here was Coast Live Oak Quercus agrifolia (below).
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| Coast Live Oak Quercus agrifolia - Elkhorn Slough CA |
Why it’s called “Live Oak” beats me, but the “Coast” bit distinguishes it from Interior Live Oak Q. wislizeni which, as is so often the case in natural history, is confusingly similar. Our location at Elkhorn Slough clearly indicated the coastal species, but the ID can be reinforced by two characteristics. First, these trees had no acorns. Interior Live Oak acorns take two years to mature, so brown acorns will usually be present behind the new foliage. Second, the leaves of Interior Live Oaks usually have five or more veins, more closely spaced than those of the coastal species, which have five or fewer. Zooming in on this photo, I’m not seeing more than five veins on any leaf.
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| Red-tailed Hawk - Elkhorn Slough CA |
Soaring over the woodland was a Red-tailed Hawk (above). You can just make out the dark head and the dark marks on the leading edge of its wings, useful ID features in flight.
Coming round a corner, we were surprised to see a Great White Egret (below) standing on the trail. It looked startled as well, flying off with a few massive wingbeats. Down by the side of the water, a Spotted Sandpiper was foraging on the mud, its tail bobbing up and down, while an Orange-crowned Warbler flicked around in the nearby bushes.
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| Great White Egret - Elkhorn Slough CA |
Walking back up to the visitor centre, which was already closing up for the afternoon, a ghost-like White-tailed Kite (below) treated us to a close fly-by, signing off a farewell to this diverse reserve.
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| White-tailed Kite - Elkhorn Slough CA |
References
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