Winging their Way to a Forest Near You

Cameron RuttBanding, Field Work, Migration, Ranges and Distributions, Research, ScienceLeave a Comment

Amazingly, we’re already well into the second half of April, which probably means a lot more to the rest of you North American birders than it does to me right about now… See, I’ve been stationed here in Manaus, Brazil, for most of the past year, which means that there is vanishingly little seasonal turnover in the mature Amazon rainforest. (If you’re not entirely sure where Manaus is, take a moment and plug it into Google Maps; wherever you are, I think you’ll be surprised at just how far I am away). Not that I’m (necessarily) complaining…

Most of our Neotropical songbird migrants winter in the Caribbean or Central America, at most trickling down into the northern reaches of the Andes or across northern South America. Indeed, very few species primarily call Amazonia home during the boreal winter: Eastern Kingbird, Veery, Gray-cheeked Thrush, Blackpoll Warbler, and Connecticut Warbler. And for those birds that do winter here, their winter ranges are often clouded in uncertainty. Take for instance the Veery (Remsen 2001, Heckscher et al. 2011). Using a comprehensive analysis of the seasonal distribution of specimens, Remsen (2001) cautiously circumscribed a smaller winter range – namely along the southern periphery of the Amazon – than was previously assumed (essentially the whole of tropical South America east of the Andes). However, without additional data from the individual birds themselves, it was impossible to know where to draw the cut-off line in the calendar year and decipher when particular Veeries are in spring migration mode and are thus no longer using a landscape as wintering habitat. But with the advent of geolocator technology, individual birds could actually be followed throughout the whole of an annual cycle. Outfitting Veeries in this manner, Heckscher et al. (2011) found that this species’ winter range actually includes all of Amazonia (based upon data from five individual birds). Interestingly, though, this includes essentially two separate wintering ranges, as individuals undergo an additional intratropical (winter) migration between two discrete wintering grounds: generally moving from the southern Amazon Basin to a scattering of peripheral locations from Venezuela to Bolivia.

Although I’ve been regularly scouring and mist-netting in primary rainforest at the Biological Dynamics of Forest Fragments Project (BDFFP, ~50 miles north of Manaus) – every month since September – my run-ins with old friends have been few and far between. In any event, here’s a short recap of those birds I’ve encountered in the Amazon rainforest since last September.

Common Nighthawk (all silent and presumed to be this species) – 12-16 October 2015 (1 individual), 23 January 2016 (6), and 16 March (13) – 16 April 2016 (6). This species is a spring and fall migrant around Manaus and primarily winters farther to the south and along western Amazonia (Stotz et al. 1992); thus, the sighting from late January is perhaps noteworthy here. Although I only just saw this species within the past week, Common Nighthawks are already thick throughout Florida and along the entire Gulf Coast (eBird data, accessed 21 April, are used for this and the current whereabouts of all subsequent species).

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It’s good to know that Olive-sided Flycatchers stay true to their character, even when they leave our sights. (Sometimes I worry that well-known birds completely abandon their personality in migration or on their wintering grounds.) Thankfully, all observations of this species in Amazonia suggest that they continue to display their classic modus operandi (flycatching from atop extremely conspicuous dead snags; 31 March 2016).

Olive-sided Flycatcher – I had what I consider to be four different individuals, based upon timing and location of sightings: 18 November 2015, 1 December 2015, 14 December 2015, and 24 March – 12 April 2016. This later timeframe almost certainly refers to the same individual (pictured above, 31 March 2016) and, indeed, I saw it perched atop the same exact snag on 26 March, 31 March, and 12 April. Olive-sided Flycatchers have previously been labeled as “rare winter visitor(s)” in the region, but I wonder – based upon these limited observations as well as those of Naka (2004) – if this species isn’t more of a migrant here. Even as my last Olive-sided Flycatcher is barely ten days old, they’ve been arriving in California and the southwestern United States, although much fewer have appeared in the East.

Eastern Wood-Pewee -I encountered only two individuals of this species: one, presumably a fall migrant, on 13 October 2015, in old second-growth forest and another overwintering individual that staked out its corner of a small forest fragment for >4 months: 21 November 2015 – 29 March 2016. In fact, every time that I banded at this latter location, I was whisked away to the eastern United States by its familiar call. This pewee consistently announced its winter territory by calling (“turwee”) and was even heard singing its full song on 10 December. This species is considered to be a regionally uncommon winter resident (Stotz et al. 1992) and has been banded five times at our study site (only in February and March). As I write this, Eastern Wood-Pewees are currently working their way up through the southeastern United States.

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This Gray-cheeked Thrush can be aged as a hatch-year (or first-cycle formative using the Wolfe-Ryder-Pyle system) by the molt limit among its greater coverts, with the inner two greater coverts replaced (no pale tips), contrasting against the remainder of the pale-tipped, juvenile coverts (21 November 2015). This means that it is an immature and was born sometime in summer of 2015 in Canada or Alaska.

Gray-cheeked Thrush – The only Gray-cheeked Thrush I saw blundered into one of my mist-nets in a small forest fragment on 21 November 2015 (pictured above). I couldn’t help but marvel at the oddity of this familiar name, sandwiched between entries of a Yellow-billed Jacamar and Dusky-throated Antshrike in my banding notebook. Throughout the long history of banding records at this location, this is only the 20th Gray-cheeked Thrush that has been captured. These can primarily be divided into fall (15 October – 26 November (10 records) ) and “spring migration” periods (1 March – 14 April (7) ) but include three additional birds that are more challenging to characterize:  5 January, 3 February, and 19 February. As was previously elucidated with Veeries, perhaps it would be unsurprising if Gray-cheeked Thrushes similarly exhibit an intratropical migration during the boreal winter, winding up around Manaus for the last leg of winter before spring migration commences. This thrush is only a very recent April arrival in North America, primarily along the western Gulf Coast.

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Like the Gray-cheeked Thrush pictured previously, this Veery can also be aged as an immature (second-year) due to the pale-tips visible on the greater coverts. This individual might be using the terra firme habitat around Manaus as its second winter home, before heading north in early to mid-April (19 March 2016).

Veery – I recorded two different Veeries here in Central Amazonia during the boreal winter, both second-year (first-cycle formative) birds: one in second-growth forest (2 February 2016) and another captured in continuous primary forest on 19 March 2016 (above). This is now the 23rd Veery that has been banded at the project, with the distribution of captures very heavily weighted towards late winter/spring: 23-28 November (4), 21 January (1), and 19 February – 10 April (18). Fifteen of the birds in this latter window fall between 2-25 March. These data conform nicely to that provided by Heckscher et al. (2011), where three of their five Veeries with geolocators arrived at their second wintering site between 15-19 February and all five commenced sustained northbound migration between 9-20 April. Veeries have already arrived on the Gulf Coast, with limited inroads north of those states immediately bordering the gulf.

Blackburnian and Blackpoll Warbler – Unfortunately, I only crossed paths with these guys once apiece: 4 December 2015 and 15 February 2016, respectively. In both instances, they were seen associating with canopy mixed-species flocks in continuous primary forest. I gotta admit, seeing a Blackpoll Warbler nestled among a Long-billed Gnatwren, Black-capped Becard, and Paradise Tanager in a bustling canopy flock was pretty special. As I write this, Blackburnian Warblers are peppering the lower Appalachians and western Gulf Coast while Blackpoll Warblers are definitely “in,” but primarily confined to Florida.

We all know that, by definition, long-distance migrants means that these birds fly a long way. But just as knowing that tiny songbirds cross the Gulf of Mexico and seeing it for yourself are two completely different things, so it is with this. For me, it is simply surreal that a bird breeding in my Pennsylvania backyard could have been rubbing shoulders (lesser coverts?) with cotingas and antpittas in the Amazon rainforest for most of the rest of the year. So as you enjoy that next cavorting nighthawk in the fading light, a flitting flock of warblers bursting into color, or that furtive thrush bounding around the bend, take a moment to ponder just where these birds have been. I certainly will the next time a “routine” Eastern Wood-Pewee or Veery finds themselves on the opposite end of my binoculars.