BLACK-THROATED BLUE WARBLERS ON ABACO


Black-throated Blue Warbler (m), Abaco (Gerlinde Taurer)

BLACK-THROATED BLUE WARBLERS ON ABACO

It’s warbler time of year on Abaco, and a good time to take a look at the Black-throated blue warbler Setophaga caerulescens. This small warbler has very particular breeding and overwintering ranges. In the summer they are found in the forests and woods of eastern North America. As the Fall approaches, they start to migrate south to the Caribbean and Central America. Abaco is one of their winter homes, as well as a likely transit stop on their way further south. Right now sightings are being reported on the mainland and the Cays.

Black-throated Blue Warbler (m), Abaco (Gerlinde Taurer)

WHAT DO I LOOK OUT FOR?

Males and females are quite different in appearance (‘sexually dimorphic’), and could even be mistaken for distinct species. Males are a deep slate-blue above (hence caerulescens) with a striking black face and throat, and white underparts. They are unmistakeable, and unlikely to be confused with any other warbler. Females are basically grayish-olive above and pale yellow underneath. For ID, look for a white stripe above the eye, a pale arc below it. In addition, both sexes have a diagnostic white patch on the the wing, that I have seen referred to as a ‘handkerchief‘.**

Black-throated Blue Warbler (f), Abaco (Becky Marvil)

The legendary bird cartoon website Birdorable, featured often in these pages, as usual has a spot-on comparison of the sexes. TBH, this is a great resource for nailing a bird’s essential characteristics. You should check out its warblers in particular! Here’s their inimitably charming take on the BTBW gender comparison.

Black-throated Blue Warbler (m & f comparison) (Birdorable)

These pretty warblers can be seen in gardens, coppice, and woodland. Although mainly insect-eaters, sometimes catching them in flight, they also eat fruit and seeds especially in winter. BTBWs are territorial, and will defend their chosen space against all-comers, including their own species.

Black-throated Blue Warbler (m), Abaco (Bruce Hallett)

WHAT DO I LISTEN OUT FOR?

As I have mentioned before, I tend to find phonetic transcriptions of bird sounds rather baffling – and often not really how I hear them myself. This is especially with the ‘Oh-dear-oh-dear-I’ve-run-out-of-beer’ and ‘Have-a-little-Kalik-at-Pete’s’ kind. One source asserts: “The bird’s song can be described  as a buzzed zee-zee-zeeee with an upward inflection. Its call is a flat ctuk”. You be the judge…

SONG Etienne Leroy / Xeno-Canto

CALL Paul Marvin / Xeno-Canto

                        

Black-throated Blue Warbler (m) (Blaine Rothauser CWFNJ)

BTBW SEX LIFE – ANY GOOD GOSS?

Black-throated blue warblers are – and I say this with considerable reservations – mainly a monogamous species. However it turns out that they have complex patterns of vocalisations and behaviours at breeding time, including very promising-sounding ‘extra-pair copulation’ involving ‘heterospecific cuckoldry’. However, despite all my efforts in researching this phenomenon more thoroughly, merely reading the intricacies quickly crossed my boredom threshold, and my own ‘call’ soon became a ‘sonorous saw-like Zzzzzzzzzzzzzzz‘.  Anyway these birds don’t breed on Abaco so I’ll spare you the details and move on.

Black-throated Blue Warbler (f) (Dax Roman / Birds Caribbean)

 IS MANKIND MASHING UP THEIR HABITAT?

BTBWs are fairly common birds within their range, with a large population. The usual stuff is happening with them in terms of habitat destruction & co at both ends of their migration. For some already threatened species (e.g. Kirtland’s Warblers), habitat degradation at either end of the migration (let alone both) presages a downward spiral in population. With BTBWs, I have read both that the population is decreasing; and in another source, slightly increasing. For now, let’s regard the welfare of the species as being stable. However, the current causes of species decline will doubtless continue, and many regard increasingly evident climate change as being a determining factor for the well-being of migratory species. The birds are not yet out of the woods, so to speak… and maybe never will be.

** anyone remember those?

CREDITS Photos: Gerlinde Taurer (1, 2); Becky Marvil (3); Bruce Hallett (4); Blaine Rothauser / CWFNJ (5); @daxroman / Birds Caribbean (7); Paul Reeves / Birds Caribbean (8).  Range Map, Wiki; Cartoons,  Birdorable; Video, Cornell Lab for Ornithology

Black-throated Blue Warbler (m) (Paul Reeves / Birds Caribbean)

“GOOD (GOOD GOOD GOOD) MIGRATIONS…”


Prairie Warbler, Abaco Bahamas (Gerlinde Taurer)

Prairie Warbler, Abaco

“GOOD (GOOD GOOD GOOD) MIGRATIONS…”

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.

PALM WARBLERPalm Warbler, Abaco Bahamas (Nina Henry)

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.

BLACK-AND-WHITE WARBLERBlack-and-White Warbler, Abaco Bahamas (Bruce Hallett)

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.

AN ILLUSTRATED GUIDE TO ABACO’S WARBLERS

YELLOW-THROATED WARBLERYellow-throated Warbler, Abaco Bahamas (Becky Marvil)

Au revoir for the time being…

Photo credits: Gerlinde Taurer, Nina Henry, Bruce Hallet, Becky Marvil; Warbler Guide PDF © Rolling Harbour Megacorp Int.

CANADA WARBLER: A NEW BIRD FOR ABACO & BAHAMAS


Canada Warbler Cardellina canadensis - Abaco Bahamas (1st record) - Christopher Johnson

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.

Abaco's 37 warbler species - permanent residents (Keith Salvesen)

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.

Canada Warbler Cardellina canadensis - Abaco Bahamas (1st record) - Christopher Johnson

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).

Canada Warbler - Birdorable

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.

Abaco Map - Little Harbour / Marsh Harbour / Bird Site (KS)Canada Warbler Cardellina canadensis - Abaco Bahamas (1st record) - Christopher Johnson

Canada Warbler - Birdorable

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).

canada-warbler-f-emmett-hume-wiki1

Canada Warbler - Birdorable

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…

Canada Warbler - Birdorable

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!

Canada Warbler - Birdorable

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. 

Canada Warbler / Bonaparte's Flycatching Warbler (J J Audubon)

canada-warbler-m-william-h-majoros-wiki

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.

NORTHERN PARULAS: ON THEIR WAY TO ABACO


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.

OLIVE-CAPPED WARBLER ON ABCO


Olive-capped Warbler, Abaco (Tom Sheley)

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)

AMERICAN REDSTARTS ON ABACO: MALES IN FOCUS


american-redstart-male-abaco-bahamas-craig-nash-fv

AMERICAN REDSTARTS ON ABACO: MALES IN FOCUS

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.

american-redstart-male-abaco-bahamas-gerlinde-taurer-2 american-redstart-male-abaco-bahamas-gerlinde-taurer-1

american-redstart-copyTEN 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
american-redstart-abaco-bahamas-gerlinde-taurer-3american-redstart-male-bahama-palm-shores-abaco-bahamas-tom-sheley
american-redstart-copy
The American Redstart (f  & m) as depicted by JJ Audubonplate-40-american-redstart-final
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A male redstart at Treasure Caybahamas-american-redstart-bm-oct-2010-copy-2
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WHAT DO I LISTEN OUT FOR?
american-redstart-male-wiki
AMRE by Mark Catesby, precursor of Audubon
american-redstart-mark-catesby-pinterest
Credits: Craig Nash (1); Gerlinde Taurer (2, 3, 4); Tom Sheley (5); Audubon Soc (6); Becky Marvil (7); ‘Scott’ wiki (8); Pinterest (9); Xeno-Canto / Jeff Dyck audio file; Birdorable (cute cartoon)

“THE DIET OF WORMS”: WORM-EATING WARBLERS ON ABACO


worm-eating-warbler-bahama-palm-shores-abaco-bahamas-3-12-tom-sheley-small-copy

“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. The Swainson’s warbler was once in the same genus, but the WEWA saw off the competition.

Worm-eating Warbler, Man-o-War Cay Abaco (Charmaine Albury)

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.

worm-eating_warbler_Andy Reago & Chrissy McClarren wiki

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

Worm-eating Warbler, Man-o-War Cay Abaco (Charmaine Albury)

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.389px-helmitheros_vermivorum_map-svg

worm-eating_warbler-tom-friedel-birdphotos-com-wiki

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

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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] 

worm-eating_warbler

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.

worm_eating_warbler_audubon-copy

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