Just like the Beach Boys who like to ‘Get Around…’, so do birds. It gives them excitations. Me too. We have ended up in France, not so much migratory as ‘occasional rare visitors’ and anyway not as vagrants. The habitat is wonderful, the foraging is excellent, but the wi-fi is a crockful of merde.
Images take an age to upload so I am taking emergency measures. Today, it’s going to be a quick look at 4 common winter warblers you can easily find on Abaco. Then I’m back to the vin.
If you’d like to know more about Abaco’s 37 warbler species (not including the very recent discovery of a Canada Warbler) click on this PDF and all shall be revealed.
The first Canada Warbler recorded for Abaco AND Bahamas (Christopher Johnson)
CANADA WARBLER: A NEW BIRD FOR ABACO & BAHAMAS
As reliable as seasonal clockwork, the migratory warblers are swarming south from their summer breeding grounds to warmer climes for the winter. In the case of Abaco, this amounts to 32 warbler species to add to the 5 resident breeding species (Bahama Yellowthroat, Yellow Warbler, Olive-capped Warbler, Pine Warbler & Bahama Warbler. 37 warblers in total.
Well, now make that 38. On August 28th, young birder Christopher Johnson was out with well-known birding sage Woody Bracey when he saw something small and yellow hopping about in the coppice. On closer examination – and he took the photos to prove it – it was not just one of the many familiar yellowy winter warblers, but a completely new species recorded for Abaco and (more significantly) the entire Bahamas. It was a Canada Warbler, Cardellina canadensis (Linn. 1766) aka Wilsonia canadensis.
The photo above is one of 3 that Christopher managed to take. In many respects it is typical of a field photograph: a small bird, at a distance, zero’d into focus through a small gap in the leaves and branches of thick coppice. Sharp bird, blurry surroundings. The trick is not to end up with a wonderful clear shot of a green leaf on its twig, with a small yellow blur in the background. (I perfected this ill-advised technique with my only photo of a Kirtland’s warbler).
WHERE WAS THIS BIRD DISCOVERED?
One of the features of the excellent birding to be found on Abaco is that some of it can be carried out in unexpected places. Town dumps are a classic example, though photos have to be taken with care to avoid unsightly rubbish-based settings. The Abaco Big Bird Poultry Farm area is another. This little bird was found there.
SO WHERE WOULD IT NORMALLY BE FOUND?
In summer, roughly 80% of CAWAs live and breed in Canada; 20% in the northern US. They spend a relatively short summer there. In the early Fall they fly down to South America. From the range map below, it looks as though their flight path would naturally take them right over the Bahamas to get to their destination. In fact, their journey is quite different. Following the central ‘bend’ of the Americas, they fly at night along a southwesterly route to the Texas coast, then on to southern Mexico and beyond.
I suspect that, as with many migratory birds, the occasional specimen takes a wrong turn on its route south, or is blown off-course by a storm. Maybe a few such vagrants pass through further east – even over the Bahamas perhaps – each year, as ‘vagrants’. But in reality their tiny size in the dense foliage of the land masses means that only a fluke sighting could result. So Christopher’s sighting will be recorded as a V5 – a vanishingly rare vagrant with only a single sighting (cf Abaco’s BLACK-BROWED ALBATROSS).
Q. DO MALES & FEMALES LOOK MUCH THE SAME? A. NO
Based on the Macaulay Library pictures below, the Abaco CAWA must be a female or an immature male. In comparing photos of this species (which I had never come across before) I have noticed one thing. The yellow lore (the area between the base of the beak and the eye) extends to include the top of the bird’s otherwise white eye-ring. This is found in both the male and the female. Now I need to check other eye-ringed species to see if this feature is a unique identifier or not…
WHAT DO I LISTEN FOR (JUST IN CASE…)?
The two sounds to listen for are the chirpy scrap of song and the ‘chip’ call.
WHAT IS THE CAWA’S CONSERVATION STATUS?
The CAWA is IUCN-listed as being of ‘least concern’. That of course is very far from saying it is of no concern at all. Surveys are already showing a gradual population decline in the breeding grounds. The Committee on the Status of Endangered Wildlife in Canada has assessed the CAWA as ‘threatened’. Dull as it is to keep repeating the point, this species like most others faces all the usual threats to its existence, mostly man-made and during my lifetime…
Deforestation, habitat destruction and intrusion, development etc etc
Problems arising from acid rain and pollution
The uncontrolled spread of the tree-destroying woolly adelgid, an import from Asia
Oh, and all those damn deer browsing the understory a bit. Blame them!
ARE THERE ANY FUN FACTS ABOUT THIS BIRD?
Well, confusion about its name, maybe, though that’s more ‘interesting’ than ‘fun’, I think. In 1760, a French zoologist named Brisson gave a name to a warbler specimen from Canada. It was “Le gobe-mouche cendré de Canada”, ie ‘The Canadian Ash-gray Flycatcher’. Because he needed a conventional Latin name for the bird, he put together the name Muscicapa Canadensis Cinerea. This did not fit in with the binomial system of taxonomy (nor was it a very good description of the bird), and the name was accordingly rejected by the wonderfully named International Commission on Zoological Nomenclature. Linnaeus (to cut a longer story short) sorted it all out in his next edition of Systema Naturae in 1766, with the binomial name Muscicapa canadensis. In due course the genus Muscicapa was changed to Cardellina.
THAT WASN’T A WHOLE LOT OF FUN. IS THERE MORE?
Well, there were more naming shenanigans when John James Audubon illustrated a female Canada warbler in Birds of America nearly a century later. Plate 73 (below) was entitled “Bonaparte’s Flycatching-Warbler—Muscicapa bonapartii.” He’d slipped in the name of ornithologist (and nephew of the more famous Emperor) CHARLES BONAPARTE,he of the BONAPARTE’S GULL. This version did not stick. However the CAWA acquired another ‘tribute’ name, an alternative that is still in use: Wilsonia canadensis. This tip of the hat is to another ornithologist ALEXANDER WILSON, of Wilson’s Plover fame.
Photo Credits: Christopher Johnson (1, 2, 3); Emmet Hume / Wiki (4); Male / Female CAWAs, David Turgeon & Bob Edelen, Macaulay Library; Audubon Plate 73, OS; William H Majoros / Wiki. Sound Files, Ian Davies & Andrew Spencer / Xeno-Canto; Abaco Resident Warbler Chart, Keith Salvesen;, Cartoon by Birdorable; Range Map, Cornell U.
The Northern Parula is one of 37 warbler species recorded for Abaco. The vast majority of these species are migratory, arriving in the Fall and leaving in the Spring to fly north to the breeding grounds. When I’m back at HQ from my computer-free break, I’ll be writing more about these little birds. Meanwhile, this post is a reminder that the influx will begin very soon. The Northern Parula, with the distinctive green patch on its back, is sure to be among them.
The olive-capped warbler is one of Abaco’s 5 permanent resident warblers, out of 37 warbler species recorded for Abaco. The other PRs are: Bahama Warbler, Bahama Yellowthroat, Pine Warbler and Yellow Warbler.(Photo: Tom Sheley)
Time to rectify an omission and to feature the striking orange and black male American Redstart Setophaga ruticilla. A while ago I posted about the equally distinctive yellow and black females HERE(the dissimilar colouring between the sexes of these little warblers is due to differing carotin levels in each). These unmistakeable winter residents are common on Abaco. They are an easy warbler for new birders look out for, being unlike any other small warblerish-looking bird. All the birds here were photographed on Abaco.
TEN REDSTARTLING FACTS (& a comment)
The Latin name means moth-eating red-tail (‘start’ is an archaic word for tail)
AMRE are among the most common New World warblers
Occasionally they are found as far afield as Europe
They are almost entirely insect-eaters, with occasional berries or seeds for variety
Males are late developers, tending to skew the sex ratio: too many of them
They are inclined to monogamy, but only to an extent. Two-or-more-timing goes on
The most aggressive males get the pick of the habitats
This all begins to sound like human behaviour(not strictly a fact, so it doesn’t count)
Their fanned tails are for display, and maybe to surprise insects into breaking cover
Redstarts suffer badly from predators, especially in the breeding season
They are popular with coffee farmers for keeping insect numbers down
The American Redstart (f & m) as depicted by JJ Audubon
“THE DIET OF WORMS”: WORM-EATING WARBLERS ON ABACO
The little worm-eating warbler (Helmitheros vermivorum) is unique. Not because of its worm-eating propensities or its warbler-ishness (or the combination), but because it is the only species currently classified in the genus Helmitheros. TheSwainson’s warbler was once in the same genus, but the WEWA saw off the competition.
SO WHAT IS A HELMITHEROS THEN, IF IT’S SO SPECIAL?
The word is Greek, meaning something like ‘grub-hunter’. And the Latin-derived vermivorum reflects the diet of a VERMIVORE – an eater of worms. But this description is, like a worm, somewhat elastic. It includes caterpillars, larvae, grubs, spiders and similar creatures. But whereas there are other warbler vermivores there is only one Helmitheros.
SOME WORM-EATING FACTS TO DIGEST
WEWAs are sexually monomorphic. Males & females are indistinguishable for most of the year
They can only be reliably sexed at the height of the breeding season
Don’t ask. OK, a magnifying glass may be needed
These birds are believed to eat earthworms only rarely. Moth larvae are their best treat
They are ground-nesting birds, one of only 5 new-world warblers to do this
Like some shore-birds, adults may feign injury to lure predators away from the nest
They are vulnerable to nest parasitism by brown-headed cowbirds** & feral cats
Fires, deforestation, habitat change & diminished food resources are also threats to the species
As are pesticides, which destroy the primary food source and are in any case potentially toxic
**cowbirds are luckily very uncommon on Abaco but are spreading their range at an alarming rate and pose a potential threat to many Bahamas bird species
DISTRIBUTION & CONSERVATION STATUS
The breeding range of the worm-eating warbler covers much of the eastern half of the US as far south as the Gulf Coast. It winters in the West Indies, Central America and southeastern Mexico. There is no overlap between summer and winter habitat. Because of the vulnerability of this ground-nesting species to a number of threats (see FACTS above), they are now IUCN listed as ‘Special Concern’ in New Jersey.
WHAT DO THEY SOUND LIKE?
In this case the song and call, as transposed into human, really does sound like the bird itself. The song is a rapid squeaky trill; and the calls for once do actually sound like ‘chip’ or ‘tseet’. See what you think.
Paul Marvin / Xeno-Canto
THE (ORIGINAL) DIET OF WORMS – A DIGRESSION
Studied European history? Had a laugh over The Diet of Worms in 1521? This was an assembly (or ‘diet’) of the Holy Roman Empire that took place in the City of Worms. There had already been several. This one resulted in an edict concerning Martin Luther and protestant reformation, with the consequence that… [sorry, nearly nodded of there. Just as I did at this stage at school I expect]
It is always instructive to look at Audubon’s fine depictions from the early c19. Here is his WEWA. Notice that it is here called Sylvia vermivora. So he had the worm-eating part, but the first part of the name rather strangely relates to a group of old-world warblers. No, I’ve no idea why.
Credits: Photos – Tom Sheley (1); Charmaine Albury (2, 4, 6); Andy Reago & Chrissy McClarren (3, 7); Tom Friedel (5). Research material – CWFNJ / Michael J Davenport; Tom Fegely / The Morning Call; assorted magpie pickings & open source
The Blackpoll Warbler Setophaga striata is a “TR3” on Abaco. Which is to say, the species is classified as an uncommon transient in its migration, and as such it is rarely seen on Abaco. Apart from anything else the window of opportunity of seeing one in the Fall or in Spring is limited by the length of time they pause on Abaco to catch their breath. Also, they are small birds that do not draw attention to themselves. They hang around in the coppice foliage rather than parading out in the open; and their call is a tiny ‘tsip‘ sound (as with so many other small birds…).
Fortunately, on Abaco’s warbler magnet Man-o-War Cay, alert birder Charmaine Albury was out and about with her camera to record a sighting. I should say that during the writing of THE BIRDS OF ABACO, I never managed to obtain a single image – however poor – of a Blackpoll Warbler actually taken on Abaco (a qualification for inclusion) from any of the many sources I used. So sadly, this pretty warbler does not feature in the book.
The summer breeding area for blackpolls covers northern North America from Alaska through most of Canada, the Great Lakes region and New England. In the fall, they fly South to the Greater Antilles and the northeastern coasts of South America. The summer and winter areas are very distinct, as the distribution map shows:
Despite their diminutive size**, blackpoll warblers generally undertake their long-distance migration – often over open water – non-stop or with a single stopover. Their migration has been the subject of many scientific studies. One of the longest distance non-stop overwater flights ever recorded for a migratory songbird was made by a BLWA. Which all goes to explain why the species is so rarely seen along the migration route: unlike many migrating birds, they make few, if any, stops along the way.
Of the many stats I have read through, I chose one to demonstrate the stamina of these little birds. In one study, an number were fitted with tiny geolocators. These revealed an average migration journey of around 1600 miles, with the non-stop trip being completed in 3 days by at least one bird.
“Transoceanic migration by a 12 g songbird”
The maps above show blackpoll warbler migrations recorded for 5 birds in a study that indicates that, while a direct overwater route is preferred in the fall migration, the return journey in spring is more leisurely, and overland (it looks as though only 3 birds made it home).
The study quoted is by William V.DeLuca, Bradley K.Woodworth, Christopher C.Rimmer, Peter P.Marra, Philip D.Taylor, Kent P.McFarland, Stuart A.Mackenzie, D. RyanNorris (Published 1 April 2015. DOI: 10.1098/rsbl.2014.1045)
** I came across the statement that “The blackpoll warbler… attains the weight of a ball point pen”. I find this an unhelpful comparison. I know what is meant, but I find it hard to think of a ball of feathers in terms of a writing instrument. Maybe it’s just me? [Astute Reader: I’m afraid so…]
YOU MENTIONED THAT THEY GO ‘TSIP’. WHAT DOES THAT EVEN SOUND LIKE?
Credits: header image of a summer bird, Cephas; all other photos by Charmaine Albury, taken on Man-o-War Cay Abaco; birdsong Xeno-Canto / wikimedia commons