Bird migration is not one fine day when all the birds decide to leave, as if on schedule, catching a flight. Although they do follow a good degree of evolution honed timing, different types of birds use different cues to get up into the sky and go.
Shorebirds, those incredible fliers, reach the evergrass and marshy habitats of the Arctic, look around for a bit and, if the breeding deal isn’t to their liking, turn around and start to head back south. That would be heading all the way to Virginia estuaries and Texas mud flats and onward, some even reaching Patagonia.
Check a map and that looks a bit exaggerated, flippant, loco. Except that birds can’t afford to be fools. Make the wrong choice, bad place to land, wrong time to fly, don’t eat enough, and it’s a Darwinian dead end. No, some shorebirds leave the Arctic early because cues tell them it’s not worth sticking around and trying to breed. Not worth the energy, better to use those sharp wings to zip it back down to the tropical mud flats, the muddy estuaries sieved by spoonbills and haunted by crocodiles.
In Costa Rica, we’ve seen potential signs of that monkish choice this past summer; Hudsonian Whimbrels and other shorebirds in June. Some were probably young birds that purposely overstayed their winter vacation but maybe not others. There seemed to be a few too many that came back early to have all been youngsters extending their tropical mudflat party.
Since then, numbers of shorebirds have been passing through the country but, for the most part, we’ve been waiting on a lot of the other birds. Yes, there have been the expected Least and Elegant Terns, and I was dealt a fortunate August card with Sabine’s Gulls and the swallows started flying a month ago. I’d be amiss if I didn’t also mention the expected pulse of Swallow-tailed and Mississippi Kites, our “early” raptors, but the bigger numbers and bird variety didn’t start happening until recent days, yesterday and today most of all.
For the past week, I glance into the morning sky over the traffic laden streets of San Joaquin de Heredia and I see small birds flapping and soaring, flying steadily east and south. Groups of six, then ten, then another ebb in the flow of Cliff Swallows over houses and busy corners. On one such corner, as with many a corner these days in urban Costa Rica, a Venezuelan mother sells lollipops for coins, for something to help support her two young children with her. The kids might be sitting on the sidewalk, might be playing on a street sign as hundreds of vehicles pass by. Some do give her something and she smiles, dozens of Cliff Swallows flying over ignored or unseen, they’ll probably fly over the same jungles of the Darien that she and her kids likely crossed going the other way.
The past few days have seen more swallows, more Cliffs and Barns and, this morning I had a few Banks too, all taking that same ancient route to South America. And now their skies are joined by other birds, mostly ones moving through the sheltered dark of night. I peer into the night sky and can’t see them, haven’t heard any but, this morning I had proof of their passing.
It had rained most of last night, a rare occurrence during these Super El Nino days. Normally, it would be raining here every night, long, heavy rains but, the overheated waters in the Pacific have turned this place into a temporary dry season. It feels like January; sun and wind with rain clouds gripping the mountains and flooding some parts of the Caribbean lowlands. But last night, we had a good, solid rain, this morning was cloudy and cool and bereft of breeze.
That’s good birding weather here, weather conducive to good bird activity and yes, it was. I walked the quiet roads in my Central Valley neighborhood, took a short stroll down the street to the wall that separates us from an adjacent rare and much appreciated farm. As usual, I scanned the massive remnant fig on the other side of the wall, a tree that, over its hundred or more years must have fed countless thousands of birds; everything from kiskadees to flocks of Amazonian bound Eastern Kingbirds, warblers, parrots, and Three-wattled Bellbirds too.
Birds still stop in it, maybe some of the same ones year after year but today, I couldn’t find anything in the thick jade leaves. Closer though, hummingbirds were sputtering and chasing each other, de-facto Rufous-taileds mostly but one on a high perch was a female Green-breasted Mango.
Another that flew to a different tree ended up being a Plain-capped Starthroat, needle beak and all!
Common birds were also calling and an Inca Dove splashed in a mini pot hole bath but I didn’t see much else. I thought, “Where’s the Red-eyed Vireos? Where’s the warblers?” Sans expectations, I strolled onwards, heading another two blocks to the water treatment area. This is our main patch of green space, our one and only occasionally smelly and slightly noisy oasis (classic birding spot), it flanks a riparian zone where cecropias, figs, and other trees grow and it’s of course where most of the birds are.
Look close and careful and you might see a Lesson’s Motmot or glimpse the Common Tody-Flycatchers and Cabanis’s Wrens that usually call from the foliage. Keep watching and more birds appear, especially in cloudy weather and, apparently, especially during the first week of September.
Peering in and beneath the trees, I glimpsed a dim flash of yellow that became a Northern Yellow Warbler. Another joined it and then there was a smart black and white bird creeping on crooked tropical branches. It’s always nice to see Black and white Warblers, so distinctive, so cool looking, just like that initial one was on the corrugated bark of a big tree at Hyde Park in Niagara Falls, 1981. I wasn’t hearing much but I kept looking, I know how sneaky these migrant birds can be when they pass through Costa Rica.
Sure enough, a bit of a paleish bird zipped into the green. Then another and another. Scanning eventually found them; Red-eyed Vireos roosting and resting I suppose. I eventually saw others foraging and more flying in and out of the vegetation; all silent, all so unobtrusive, I must have seen a dozen and figure that the parks and remnant precious green spaces in the Central Valley must host hundreds of the hidden birds.
I kept watching and a small pale bird moved in a Cecropia. I was immediately on it with my bins and yes, maybe because of its pale color or other subtle subconscious hints, it was a bird I had suspected it to be; Cerulean Warbler! Gem blue and cloud white, it busily inspected the thick Cecropia foliage before joining the Yellow Warblers in thicker, more tangled cover.
Feeling grateful and elated, I figured I’d better watch some more, see if I could lucky with an ultra sly cuckoo or maybe a less common warbler. There were also nice resident species to watch; a pair of Lineated Woodpeckers flapping into view, beautiful Hoffmann’s Woodpeckers too and the common kiskadee trio (Great Kiskadee, Boat-billed, and Social Flycatchers). Blue-gray Tanagers also sort of got into the way and a Black Phoebe perched and called behind me.
It was some nice birdiness and then it got bird crazy! Out of nowhere, as I visually checked the foliage for hints of movement and out of place shapes, a dark bird with pointed wings flies right in front of my field of view, eye level. It swoops around in a circle and then cuts off to the other side of the trees. I find myself saying out loud, “Common Nighthawk!”
I don’t know if I flushed it or if the nighthawk had suddenly flown in but I was pretty happy to see it. Although these summer time nightjars pass through the Central Valley, the numbers are small and who knows how many fly over unseen, up in those dark skies? To see them for the year, I usually have to go to the Caribbean lowlands or coast, it was fantastic to see one this morning, and at such close range.
Not long after the nighthawk had bird bombed my vireo searching, the sun came out and a breeze picked up. As expected, the already subtle migrant bird activity quickly died down and I started walking back home. On the way, in the view over houses to a distant McDonalds, churches, and the airport, I saw a slender bird in flight and there the nighthawk was again. Assuming it was the same individual, it hadn’t gone to roost, there it was, boldly and quickly covering ground as it flew over the houses. I hope it found a good roost, I hope it’s somewhere much further south tonight as it flaps and glides towards Brazil.
I had a good morning but, checking eBird lists, I wasn’t the only one. A birder reported 100 Common Nighthawks on the coast, and my friends Juan Diego and Maria Jose of Lifer Tours had some yesterday and today at The Nest along with several Ceruleans, Prothonotary Warbler, and other migrants.
Over by Naranjo, Jim Zook had a rare Yellow-throated Warbler along with other migrants, and one of the Garrigues sons (of Richard Garrigues, author of the Birds of Costa Rica a Field Guide) had a dozen Upland Sandpipers (!) at the airport as well as various migrants near there.
Yes, the pace of bird migration in Costa Rica has definitely kicked up a notch, what will tomorrow bring?
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