Say ‘fall-out’ and birders will go glassy-eyed and remember where they were there when it rained birds. In an average lifetime you don’t get many fall-outs, so when they do happen they must first be savoured to the very last feather, and then dissected until the reasons for the fall-out are somewhat understood. In truth we cannot put all the species encountered in a fall-out into neat compartments and the one experienced here in southern Nova Scotia between October-25-28, 2017 has some baffling components.
The date range may confuse, but I believe that indicator birds, such as Indigo Bunting, actually starting to arrive on the afternoon of October-25; were largely missed during October 26 due to high winds and rain squalls until the evening, their presence becoming evident when the rain cleared. October-27 will be remembered as THE day though, as that was then when weather conditions allowed observers to take to the field and begin the recording process. The fall-out continued through October 28 and into November, but only really in terms of birds that had already arrived elsewhere and that then started moving into birded locations, thus we saw probably the best, most diverse action on October-28.
The scale of the arrival can only be extrapolated from the data, it certainly encompassed all of southern Nova Scotia, stretching north to Halifax although the species mix there differed a little. Comparisons have naturally been made with the last big Nova Scotia fall-out, October 1998, when it also rained birds but that time as a torrent compared to our healthy, refreshing shower. The action in 1998 took place within a very limited geographical location, essentially only extremely southern Nova Scotia. A comprehensive review of that event can be found here:
The species mix for the 2017 fall-out intrigues. Some species might have been expected to be more numerous, others were probably a part of a normal late October migration that got sucked in and lumped with the mass. How many birds and species were actually affected by the conditions responsible for the fall-out we will never know but we can analyse the physical evidence (sightings) and speculate. In reviewing the data, eBird has been the essential reference even though it is limited to the data entered (obviously). Ideally, when the fall-out was detected, (Dave Bell called it ‘officially’ on the evening of October-27) birders would have dropped everything, assembled before dawn in the best areas and teams of two allocated sites to check. In practice of course, those available and willing went at it like a Bull at a gate, such is human nature.
The reasons for the fall-out will no doubt be better explained by others elsewhere but, put simply, birds in the US in the process of moving to their winter quarters encountered good migration conditions and so began to move. At some point during their progress, the prevailing southerly airflow pushed them north and out to sea. They hit a weather wall further east (over the ocean) which forced them into a narrower track and back over land, resulting in landfall from northern Maine and coastal New Brunswick to largely the southern half of Nova Scotia.
This piece is based on my personal observations of species plus some conjecture regarding absentees. Short days and the limited number of observers really only gave a snapshot of the event, and I’m sure all cogent birders were wondering just how many birds must have been on Seal Island? For those reading this based in locations where the numbers and variety of species involved is nothing too newsworthy, just remember we are talking about Nova Scotia and all records should be viewed in a Nova Scotia context. The standard Nova Scotia reference, ‘All the Bird of Nova Scotia – status and critical identification’ (McLaren, 2012) will give you all of the context you need. Data mined from eBird and filtered as best I could to avoid duplication.
The Main Players
The write-up starts with the marquee rare species; that is species that they are not normally found in NS except as a vagrant. I appended the rough number of birds recorded during the fall-out period after the species’ name, all eBird sourced, and a short description of their wintering area.
Perhaps the main marker species was White-eyed Vireo – 68, (winters in, well it is complicated but south!). It breeds in the southeastern United States from New Jersey west to northern Missouri and south to Texas and Florida. Populations on the US Gulf coast and further south are resident, but most other North American birds migrate south in winter. The northern subspecies occupies most of the range of this species and is fully migratory and so likely the one we got here. This sub-species is larger and has more brightly coloured plumage than all other subspecies, I don’t recall a dull one! In Nova Scotia, White-eyed Vireo does occur annually but they are far from guaranteed and given their quite secretive nature, we can safely assume that only a small percentage are ever discovered.
Yellow-throated Warbler – 37, (winters mostly along the Gulf Coast, eastern Central America, and the Caribbean). This is one of those species everyone loves to see. In NS they are annual in varying but low numbers. We get two forms, look them up in your field guide. Put simplistically, the forms consist of ones with yellow at the front of the supercilium (Dominica) and ones whose supercilium is white, or at least mostly white (albilora). There are also intergrades and a resident subspecies best ignored. The majority of our fall-out birds appear to be (answers on a postcard!).
The third species of the ‘big four’ was Yellow-throated Vireo – 19, (winters Mexico through Central America). In NS this is a good bird with probably two to five records annually. I’d only had one in Nova Scotia up until the fall-out, now I have four for CSI, something that may not happen again in my lifetime.
Hooded Warbler – 18, (wintering in Central America and the West Indies). This attractive warbler is as common, more or less, as White-eyed Vireo in NS, so the presence of numerous individuals suggests that they both come from the same core breeding range and that they both move to wintering grounds at the same time and to similar wintering areas too. On Daniel’s Head, a male with a bill deformity took up residence in one set of isolated trees, showing beautifully. Had that bird been on say an island off the UK or Ireland, I wonder how much of an impediment the bill deformity would have been to gaining acceptance as a wild bird. Such deformities are said to be prevalent in cage birds although, as cage birds are kept for their looks and deformities detract from those looks, it has never really rung true.
Rarities, but not many of them
A real prize of the fall-out was Golden-winged Warbler – 2, (winters southern Central America, northern South America). It is genuinely hard to find in NS although 2018 had already been good for them. Equally as elusive but perhaps fractionally commoner in NS in general was Blue-winged Warbler – 3, (winters in southern Central America). Occupying the same ecological niche as Golden-winged, Blue-winged seemingly dominates the gene pool to the point of producing frequent and identifiable hybrids with Golden-winged. Blue-winged is also believed to be edging Golden-winged into a contracted range or even, in the long term, species extinction through hybridisation. Blue-winged Warbler is another good bird to see in NS, and, as it expands its range, it may get as regular here as Prairie.
Yellow-billed Cuckoo – 31, (winters in Central America to northern Argentina.) This beauty is a traditionally late migrant to NS, presumably a reverse migrant. Although it put on a good showing in terms of numbers, particularly on Bon Portage and in the Halifax and Kentville areas, not many stayed put which probably means some duplication of records as birds moved location.
Fall-out species recorded in above normal numbers but not ones to get you chasing were Red-eyed Vireo – c75, (winters in South America) and the following warblers, Magnolia Warbler – 12, (winters southern Mexico and Central America); Blackburnian Warbler – 6, (winters in southern Central America and in South America); Black-throated Blue Warbler – 7, (winters in the Caribbean and Central America); Black-throated Green Warbler – 13, (winters in Mexico, Central America and the West Indies); Blackpoll Warbler – 18, (some move to the Greater Antilles, most go to the Northeastern coasts of South America in one flight!); Black-and-White Warbler – 6, (winters in Florida, Central America, and the West Indies down to Peru); Northern Parula – 33, (winters in southern Florida, northern Central America, the West Indies/Lesser Antilles); Common Yellowthroat, 20 and American Redstart – 10, (winters in Central and South America); Tennessee Warbler – 9, (winters in southern Central America and northern South America). Palm Warbler – 10 (winters in the southern US, Mexico through Panama and the Caribbean) was probably not affected by the fall-out conditions as many were western form birds which would normally find their way to NS in autumn and were presumably discovered thanks to saturation field coverage of some popular spots.
Away from the warbler end of the market, perhaps the single most abundant species of the fall-out was Indigo Bunting – 225 +, (winters southern Florida to northern South America), followed by Rose-breasted Grosbeak – 58, (winters in tropical America), Summer Tanager – 29, (winters Mexico through Central America and northern South America) and Scarlet Tanager – 23, (winters northwestern South America, via Central America). Given the presence of many sympatric species, Blue Grosbeak – 6, (winters mainly Central America) was also underrepresented. Swainson’s Thrush -12, (winters Panama to Bolivia but also a few in the Caribbean). They were mostly on Bon Portage and may have just been progeny of late breeders? Another interesting arrival that just made the common list was Ovenbird – 6, (winter in Central America, the Caribbean islands, Florida to northern Venezuela). Perhaps they too had almost completed their autumn migration when the fall-out happened.
An abundant and lingering fall-out bird was Grey Catbird – shish!, (winter range from the southeastern United States, through Mexico into Central America and the Caribbean). Given that they were well into their migration it is not so surprising that we got so many (100s).
Orange-crowned Warbler – 34, (winters southern US through Central America but it moves over a protracted period of time and is even occasionally common in the early winter in NS) is a hard one to call as there had been a good mid-October arrival in the province and they seemed to be in every chickadee flock you looked at. It is quite possible that those found during the fall-out had already arrived with the intervention of weather and were just found as a by-product of the concentrated birding.
Present but under five recorded
Interesting records, because of their normally early departure and/or distant wintering grounds, were Bay-breasted Warbler – 1, (winters in southern Central America and northern South America). Chestnut-sided Warbler – 4, (winters in Central America south to northern Colombia), and Nashville Warbler – 4, (winters Mexico, and the northern bit of Central America). Surprising were records of Chimney Swift – 4, (winters primarily in north and western South America). Wilson’s Warbler – 2, (winters from Mexico south through much of Central America) was barely affected and those found may have just been lingering regular migrants. Pine Warbler – 3, (a percentage of the population winters in the Caribbean and northern Mexico, we get them in winter in NS too), interestingly all three reports came from Bon Portage although more were found in late November onwards, presumably typical wintering birds. Cape May Warbler – 3, (winters in the West Indies).
Also interesting were the relatively few records of Blue-headed Vireo – 10, (depending on the subspecies, winters as far south as Central America) certainly there were a few around but whether these were affected by the fall-out conditions or other factors in difficult to say as most didn’t actually show until into November.
It is hard to formulate a theory on why the following showed up in such small numbers. Not in any particular order but, Wood Thrush – 1, (winters mostly in the tropics) happened to drop in to a birders yard in Lunenburg Co and then was only present briefly, something that a few species have in common. It might be reasonable to have expected more Wood Thrush to appear, but it is likely that they were already long gone by the time the storm hit. Veery – 1, (winters eastern South America)is another early mover and so one on CSI while no doubt a part of the fall-out, stands out along with Grey-cheeked Thrush – 2, (winters in the Amazon basin with a very few in the Caribbean), one well inland.
The two waterthrushes were as you might expect although a few more northern would have been expected. Northern Waterthrush – 1, (winters Central and northern South America and the Caribbean). No Louisiana Waterthrush, (winters in the West Indies and Central America) were reported or expected. They are one of the earliest movers to their winter quarters and records in even September away from their winter range are rare.
Where the heck were they?
A puzzling rarity question is; where were the Kirtland’s Warblers, (winters in the Bahamas) and what about Swainson’s Warbler (winters Greater Antilles to Yucatan) and even both Worm-eating Warbler, (winters Mexico to Central America) and Cerulean Warbler, (winters South America, moves early). Also missing in action! Where were the Yellow Warblers, (winters Central America through northern South America) why didn’t we get a Bicknell’s Thrush, (winters in parts of the Caribbean) where did the late Canada Warblers, (winters southern Central and South America) go? Also no Warbling Vireos, (winters Central America) were found and maybe a long awaited Loggerhead Shrike, (winters souther US and northern Central America) might not have been out of the question. We might have reasonably expected a Prothonotary Warbler, (winters Central America through northern South America) certainly a Mourning Warbler, (winters Central America through northern South America) and perhaps even Kentucky Warbler, (winters Caribbean and Central America)but alas, not this time. As for Connecticut Warbler, (winters northern South America) they fly high and south and would not be expected to be either moving or influenced by the system responsible.
Bobolink, (winters South America) an October bird in Europe where it is a prize rarity, and so some might have been expected to be affected. Bell’s Vireo, (winters Mexico and parts of Central America) has a core breeding range being to the west and south which kept them out of the mix. Blue-gray Gnatcatcher, (winters in the Caribbean and southern US through Central America) might also have been expected with the main fall-out, similarly Eastern Bluebird, (winters in the southern US) but none showed at the time. Records of gnatcatcher in NS later in the late autumn may just have been typical reverse migrants. Brown Thrasher, (winters in the southern US) was another absentee although it may have been present in such small numbers, such as one, as to be overlooked.
Almost finally, Prairie Warbler, (winters in the Caribbean and northeastern Mexico) was unaffected which, as it is a common bird in the Caribbean in the winter is a surprise but perhaps the method of their movement explains their absence. Short flights down the eastern US seaboard and a short hop out to the Caribbean while the border guards are not looking. We might have expected a Yellow-breasted Chat, (winters Mexico through Central America but also occasionally in the US or even Canada) or two but none seem to have arrived, likewise, Grasshopper Sparrow, (winters southern US through Central America and the Caribbean and Orchard Oriole, (winters throughout Central America to northern South America) could be added to the, I’m surprised we didn’t get one list.
The last group to look at are Flycatchers although they were poorly represented with only Eastern Wood-Pewee – 16, (winters in Central America and parts of northern South America) being seen (see pewee problems below for a bit more). Interesting that no Great Crested Flycatchers, (winters Mexico and parts of Central America) got caught up in the movement and that we didn’t bag a Grey Kingbird, (winters Caribbean to northern South America) presumably both species had moved too early to be affected.
To summarise: A fall-out of birds, many being rare to scarce on Nova Scotia, occurred in late October 2017. For a few sweet days we were able to browse warbler flocks that are normally gone from the province a fortnight or so earlier than the end of October. Each flock held a prize, even if it was ‘only’ another White-eyed Vireo. Such fall-outs are the staple of active birders everywhere and we should feel privileged to have experienced this one. The rapid departure of many birds in the days after the fall-out suggests many successfully reoriented, although many will also have perished. If climate change continues apace, bringing the weather combinations required to influence migration so, then such fall-outs may become expected, even routine which may diminish the novelty value of some species, relegating them to scarce migrant status as opposed to vagrant. Until that happens then the events of late October 2017 will live long in the memory of those who experience it.
We live in the east and are rarely troubled by the old pewee problem. Ours are eastern, western stay western, mostly. There are a few Nova Scotia records of Western, mostly singing or at least calling birds, so what do you do when the autumn dumps a problem pewee on your lap? Well you just have to give it a go.
The now legendary fall-out of birds of October-26-27+, 2017 gave us lots to look at and think about. It also masked any arrivals not affected by the fall-out but who just gate-crashed the whole party. One potential coat-tail rider was this pewee that Paul Gould found on Daniel’s Head, up past the bit we call ‘The Alders’. Although I’d already seen a pewee, an apparent Eastern found by Mike MacDonald along Kenney Rd, I was keen to see Paul’s as part of my “see everything on CSI from the fall-out’ policy.
There is a paper regarding pewee identification (link below), well worth a read even though you will get fed up of reading the word ‘gestalt’. I think they mean jizz, which means what a bird looks like in respectable English. The folks in the USA have appropriated the word jizz to mean ejaculate (stop giggling, what are you, 12!), or perhaps it is just that pewees and the like do it for them, not sure, funny people! Here is the Wikipedia definition of gestalt, I can see what they mean: Gestalt: a German word for form or shape, may refer to: Holism, the idea that natural systems and their properties should be viewed as wholes, not as collections of parts. And jizz, the clean version from the same source: Jizz or giss is a term originally used by birdwatchers to describe the overall impression or appearance of a bird garnered from such features as shape, posture etc.
To summarise, the following may indicate that a silent wood-pewee is a western because:
The bill has an extensively dark lower mandible.
The upper wing bar is paler than the lower, even almost non-existent.
Gestalt – tail angle. 80% hold their tails straight. Easterns were 60% up, 7% down. The tail angle easterns normally adopt tends to make them look empid-like.
Overall colouration: Eastern tends white underneath, western more uniformly duller.
Ratio of primary extension over tail extension: PE = primary tip to tertials. TE = primary tip to tail tip. Eastern ration is equal to or less than 1. Western is approximately 1, so , less than 1 should mean eastern, or not. I find this confusing to say the least.
First off, here is a known Western Wood-Pewee from Arizona, taken in September 2011. It mostly complies with the pewee paper’s conclusion except for the wing bars. I think Western has a miserable look due to the all, or mostly dark bill.
Now on to Paul’s bird. Here is his photo, a small image but it hints at Western. The tail is in line with the back, it looks uniform too. The wing bars are a bit obvious and the bill is not all dark, but then neither are all Western Wood-Pewees bills.
Unfortunately my shots of the western candidate are not all I would have hoped for although this should not affect a conclusion, based on the ID paper.
This is the Daniel’s Head bird in shade and low light. Note the wings doing the 65% eastern thing, assuming you read the ID paper. You can’t see the bill so well here but the lower mandible is 80%+ dark. Note the uniform looking appearance too; the underparts are not so white. The wing bars look bolder on the lesser coverts, they shouldn’t be on a Western supposedly.
Here is the same bird on a different perch and in more illumination. The 65% eastern tail remains.
Now for a look at the first eastern from nearby Kenney Rd, should I ask the wing bar question again?
And before we move on to more photos of the pretender, here is what appears to be a second wood-pewee, again from Kenney Rd and a few days after the first. I say different based on the extent of black on the lower mandible.
It may be that posture on this bird makes the wing-bars look a little different.
Going back to 2015 and this bird sat on a wire on The Hawk. Clearly a wood-pewee, presumed Eastern although the shape is ambiguous and it does look a little miserable.
And now a couple of known Eastern Wood-Pewees, see how different they look.
Conclusion: Some of the features shown by the Daniel’s Head bird (and even the Kenney Rd one) are suggestive of Western Wood-Pewee but they don’t have the ‘look’ of a Western. Given the events of the fall-out both (or all three) should be treated as Eastern. Discuss?