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.