Costa Rica part 5: waders/shorebirds at Punta Morales Saltpans; 10/04/2017   Leave a comment

This post covers a couple of hours visit to a single site, the commercial salt pans at Punta Morales in north-western Costa Rica. As waders (or shorebirds as they are known in the Americas) have a universal appeal to birders I have dedicated an entire post to this short visit and have attempted to illustrate every wader seen plus a few of the terns. We visited some salt pans in this area in 1981, possibly the same place. Nearly all the species would have been lifers then, now none of them were, but I enjoyed seeing them just as much as I did the first time.

 

An early afternoon visit to the salt pans was most successful. Unfortunately we only had two scopes between us so initially it was a slow process getting onto all the waders. However as we walked around the pans we found we could get close enough to most birds for decent photos and indeed I think I managed to photograph every wader present.

 

Many birds were on the bunds between the pans, others were wading in the brine. This mediocre photo has been included as its the only photo I took of Grey (or Black-bellied) Plover, seen in the top right.

 

There were large numbers of Black Skimmers present. A not particularly appropriate name as all three species of skimmer show a similar black and white plumage and this is no more black than the other two. These aberrant terns feed by flying low over water with their long lower mandible just below the water’s surface (the so-called ‘unzipping the pond’), if the lower mandible encounters a prey item the upper mandible snaps shut to secure it.

 

With the skimmers was a small number of Royal Terns. Recent genetic work was shown that the African and American forms of Royal Tern have diverged sufficiently to be considered separate species,  but as yet I haven’t heard of any reliable ways of separating them in the field, not has this discovery been taken up by mainstream world checklists.

 

At the back are three black-billed Cabot’s Tern’s named after  American physician and ornithologist Samuel Cabot III. This is a recent split from the Old World Sandwich Tern, although the American checklist committees SACC and NACC have yet to ratify this (but the IOC and BOU has). In the foreground is a ‘Hudsonian’ Whimbrel. This larger, more strongly patterned, dark-rumped version of our Eurasian Whimbrel has been treated as a separate species by the BOU, but not by the IOC or other world checklists. As the BOU will adopt the IOC checklist as the basis of the British List as of 01/01/18 then we will lose this one from the British List (there have been a few records of this American form in the UK including along-stayer in Cornwall).

 

Most of the species of wader present have occurred as vagrants in the UK at some time or other (hence British birders interest in American waders) but one that hasn’t is Wilson’s Plover which has a more southerly distribution than most.

 

Also known as Thick-billed Plover this species breed from SE USA to Belize and the West Indies and winters as far south as Brazil.

 

Another species that has not made it to the UK is Marbled Godwit which has an interior distribution in North America and doesn’t make any of the major ocean crossings that seems a prerequisite for regular trans-Atlantic vagrancy. A single Whimbrel is the middle of the flock facing left.

 

Here Marbled Godwits can be seen with Black-necked Stilts, Stilt Sandpipers and a single Willet.

 

Marbled Godwits in flight, unlike the other three species of godwit they don’t show either white wing-bars or white rumps..

 

Yellowleg species were surprisingly scarce on this trip. perhaps they had already departed for their breeding grounds in North America. This is the Greenshank-sized Greater Yellowlegs. I saw my second UK Greater Yellowlegs in Hampshire in 2015 but Lesser Yellowlegs is much commoner, one stayed at our local patch for seven months from September 16 and eventually departed after I had left for Costa Rica in late March.

 

Closely related to the Old World Black-winged Stilt, the Black-necked Stilt of the Americas was common on the saltpans. There are four ‘black-and-white’ stilts worldwide differing only in the precise pattern of black and white on the head, neck and back and there is a good argument for lumping them all together.

 

Joining the Stilts, Godwits and Whimbrel in this photo is a single Stilt Sandpiper in the foreground and four Willets. This omnatopoeic bird surely consists of two species, Eastern and Western Willet (these are all Western Willets) and a proposal to split the two forms is being considered by the NACC currently, here is a summary taken from the proposal: The Willet (Tringa semipalmata) includes two broadly allopatric subspecies that exhibit morphological, ecological, vocal, and genetic differentiation. The eastern subspecies (T. s. semipalmata) breeds almost exclusively in saltmarshes and brackish coastline habitat along the Atlantic Coast, the Gulf of Mexico, and certain localities in the Caribbean In contrast, the western subspecies (T. s. inornata) breeds in brackish and freshwater wetlands in the Great Basin as well as prairies in the north-western United States and southern Canada. The western subspecies winters along rocky habitat on the Pacific coast from the north-western United States south to Chile. While the two species may co-occur during migration and on certain wintering grounds, pair bonding occurs on breeding grounds which are allopatric between the two subspecies. For more see: http://checklist.aou.org/assets/proposals/PDF/2017-A.pdf

 

There were a number of Short-billed Dowitchers on the pans. This is a difficult bird to separate from the similar Long-billed Dowitcher (and no, bill length isn’t much help) especially if they are silent. Long-billeds are regular if scarce in the UK but Short-billeds are mega rarities, the one at Lodmoor, Dorset in 2012 was only the 3rd for the UK.

 

Here is a better portrait of one species that has appeared in the background in previous photos – Stilt Sandpiper, (not to be confused with the unrelated Black-necked Stilt at the back). A regular migrant in the Americas, this is a very rare species in the UK although I have seen three in Dorset or west Hampshire over the years.

 

Here a Ruddy Turnstone, a very common species in the New World and the Old, perches behind the New World Spotted Sandpiper.

 

The New World Semi-palmated Plover is very similar to our Ringed Plover. Small differences in the bill and facial pattern separate the two and of course there are the semi-palmations between the toes for those with very good scopes and perfect viewing conditions. But the best way to locate a vagrant Semi-P Plover is by call.

 

It’s now time to look at the smallest waders, the so-called ‘peeps’. This, a Semi-palmated Sandpiper, was by far the commonest.

 

Semi-P Sandpipers and a Semi-P Plover. with a single Least Sandpiper at the far right.

 

A flock of Semi-palmated Sandpipers beautifully reflected in the brine solution.

 

This flock of ‘Semi-P Sands’ is joined by a single Stilt Sand and a Semi-P Plover. Notice the bird in the far lower left, the long curved bill means that this is almost certainly a Western Sandpiper on route to Alaska or far-eastern Siberia. Relatively easy to separate in juvenile or in breeding plumages, winter plumaged adults can be very tricky. They winter further north than Semi-Ps, a lot of them within the southern USA and they were much rarer than Semi-Ps in Costa Rica.

 

Perhaps the rarest bird at the pans and one that had never been recorded by Birdquest on their many trips to Costa Rica was this Wilson’s Phalarope.

 

There were relative few non-waders/terns at the pans but this Great Egret posed for its portrait. The taxonomy of the species isn’t settled either with the small far-eastern subspecies modesta probably deserving species status, whilst the New World alba differs from the Eurasian form in bare part colouration, breeding plumes and display.

 

As was always the case we didn’t have enough time to really study all the subtle features of these fascinating waders and soon it was time to leave the pans and head for Hacienda Solimar which will be the subject of the next post.

 

…. but we’ll end this post with a portrait of the world’s smallest wader, the appropriately named Least Sandpiper.

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