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biodiversity bird finding in Costa Rica Birding Costa Rica

Streak-chested Antpitta in Costa Rica- One or Two Species?

During these apprehensive times of self quarantine, social distancing and much of life on pause, I often do what millions of other Earthlings tend to be doing; visually engage with the screen of a computer, a tablet, or a phone. Since I can’t stand messaging by phone or using it as a mini computer (I guess because I’m still stuck with this antiquated idea that phones are (were) for talking with other people), I find myself moving between the tablet and the laptop. I even use both at the same time but still try to remember to be productive, still try to make use of this time to work towards goals, digitally step my way to any number of future finish lines.

But it’s not all robot time, once in a while I do get up to look out the back balcony to see birds like this one.

While attempting to use time in a productive manner, I also find myself veering off the path, musing about things I would love to study but for which I shouldn’t really invest as many hours. Sometimes, the errant thoughts gain hold, pull me into an inviting whirlpool that promises knowledge. But, as with any species of maelstrom, it can be a challenge to find the exit door, to leave. We all have our personal Hotel Californias; some are merely time consuming, others can be dangerous. Fortunately, one of the mental realms that magnetizes my attention involves nothing more than learning about birds and last night, the rabbit hole took the form of antpitta vocalizations. Not just any antpittas either but Hylopezus species. In non-birding vernacular, that means a smallish, brownish feathered ball with legs that calls over and over unseen and teasing from dense vegetation.

This Thicket Antpitta from Lands in Love is one of them. Formerly known as the Fulvous-bellied Antpitta, I used to tell people that to avoid unwanted conversations on trains and planes, just start talking randomly about “Fulvous-bellied Antpittas”. I tried it once on a train route from Washington state to Buffalo, New York but it backfired, the guy actually became interested in what I was saying.

Having access to the Birds of the World doesn’t make it easy to extract myself from exploring the depths of avian information but then again, it’s a great place to mentally lounge. When one can explore birds by genus and family, it’s just too easy to roll with the avian taxonomy, look at their similarities, their subtle differences, and see where they occur. It’s fantastic to have the chance to look at images of those birds, even watch video footage, hear what they sound like. Having an inclination for the auditory side of existence, I find access to this latter aspect of bird knowledge particularly tempting.

I love to listen to what all of those birds sound like, my only complaint is that I can’t choose and listen to several at once for a direct, real time comparison (at least on the same device). Listening to some birds also sometimes reminds me of things I wanted to look into, one of those being the differences in songs shown by the Streak-chested Antpitta.

A Streak-chested Antpitta from Carara National Park, one of the best places to see this species.

In Costa Rica, the Streak-chested Antpitta is an uncommon species of interior lowland and foothill rainforest on both slopes. Since it seems to be absent from various areas of rainforest habitat, it is likely subject to edge effects and probably has a preference for certain microhabitats inside forest such as flat or level areas.

I have known about the differences shown between birds on the Carribean and Pacific slopes of Costa Rica for some time but have never tried any playback experiments nor do I have the capacity or time to adequately measure and study the vocal differences found within that species. But, I can mention it here with the hope that others will be able to carry out molecular and extensive vocal studies to determine whether or not two or more species are involved when talking about Hylopezus perspicillatus.

Last night, my interest in this bird was renewed after listening to differences in vocalizations shown by two recently described species in the Spotted Antpitta complex from South America. Formerly lumped with Spotted Antpitta, both Alta Florest Antpitta and Snethlage’s Antpitta were split from that species based on a combination of morphological, molecular, and vocal differences. Most of the emphasis for splitting was placed on the differences in loudsongs between those taxa and since they still sounded fairly close, I figured I would take another look at Streak-chested Antpitta. Could I see differences between Streak-chested Antpitta songs using the same or similar parameters? Would that be even possible by comparing sonograms and would there be enough differences to argue for the occurrence of two species?

In brief, after reviewing recordings of this species from Honduras to Ecuador on Xeno-Canto and eBird, two main songs are evident; one pertaining to birds that occur from Honduras to western Panama on the Caribbean slope (the intermedius subspecies), and another to all other subspecies ranging from southern Costa Rica on the Pacific slope and the Canal Zone of Panama to Colombia and western Ecuador.

In looking at photos, the higher degree of rufous on the flanks described for this subspecies is evident (although it’s hard to see in this photo).

Although I didn’t measure vocal differences between both vocal groups, a cursory look at sonograms and listening to each type of song from several individuals appears to point at differences in frequency and structure or pattern of the song. There may also be differences in note structure, especially between the first note but off hand, note structure looks quite similar overall.

For example, in intermedius, the song seems to be mostly above 2 kilohertz in frequency and starts with a distinctive highest pitched note of the song, goes lower for the second note, goes up a bit in frequency for the third note and stays at that frequency for the next two notes before descending in frequency for the last three or four notes. In other words, the song starts high, goes low, then up and level before descending.

In the other subspecies, including birds from southern Costa Rica, the song seems to be mostly below 2 kilohertz and starts on a lower note, slightly ascends in frequency for two or three notes and then descends in frequency with the final note possibly at the same frequency as the starting note. In other words, the song goes slightly up and then back down.

Both types of songs seem to slow down in pace at the end and may also have the same number of notes. Although they may or may not significantly differ in pace, they do seem to differ in other ways. Would these differences be enough to argue for species status? To answer that question, we probably need a measured and adequate statistical analyses of these two song types backed by playback experiments. The results of that study alone might even be enough to make an argument for splitting this species but studies that also use morphological and molecular characters would be even better. If any grad student out there is looking for a project, this might be a good one…

On that note, the same can be said about the Thicket Antpitta (Hylopezus dives). While checking out vocalizations of the Streak-chested Antpitta, I was reminded that the Thicket also has disjunct populations from Central and South America and guess what? Their songs also differ.

This is a song of a bird from Costa Rica that is typical of populations from western Panama north to Honduras:

This is a song of a bird from Colombia typical for birds from the Darien and South America (although there might be some differences between birds from the Choco and eastern Colombia):

The differences are notable for pace, number of notes, and what seems to be note structure. With that in mind, it seems that these two main groups of Thicket Antpitta also merit further study. I wonder when I can start with playback experiments?

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biodiversity bird finding in Costa Rica

Birding Costa Rica May, 2020- a Time for Discoveries

May is the golden birding month, the magic time when any visit to green space comes with an exciting promise of possibility. Birds are on the move, millions of birds and the uncommon ones, even the outrageously rare ones can be anywhere. A seriously lost Fork-tailed Flycatcher is more likely to appear where weather and geography move and funnel other birds but there’s always a small chance of it gracing the local patch.

Locally common in Costa Rica.

Happily, the only way to find out, to see what has flown in during the night is by going birding and in May, there will be birds. At least up north there will be birds and they will represent with bright plumage and constant song. It’s a wonderful time to walk in woods made fragrant by fresh leaves, new blossoms and the chestnut beauty of Bay-breasted Warblers high above, flashy Magnolia Warblers below.

In Costa Rica, the May warbler parade passes us by but this month can still be an exciting time for birding. This truth was recently made known by several exciting finds, discoveries that would have never been made, would have never been imagined, if local birders hadn’t gone into the field to look. Check these out!:

Hooded Merganser at Lake Arenal

This would be like seeing a Smew in Buffalo, NY, or finding some other, very rare vagrant, lost duck in the Netherlands. Even though some years ago, a female of this species also made an appearance in Costa Rica, this second country record was still very much unexpected. A bird that normally winters only as far south as northern Mexico isn’t really on the rarity radar for Costa Rica and especially not in May. But, on May 16th, that did indeed happen when a female Hooded Merganser was found by Ever Villegas near Nuevo Arenal. On that day, local birder Dennis Palma also helped other local birders tick this serious mega for Costa Rica. I’m not sure if it is still there, I hope so and that it stays for a while!

Hudsonian Godwit at Paquera

Having found the second documented record of Hudsonian Godwit for Costa Rica in 2014, this rare long distance migrant is on my mind every spring migration. Although most fly over Costa Rica, I believe that a few must also stop off in this country each April or May. The increase in local birding has indeed resulted in a few more sightings of this species but finding one is still akin to winning the lottery. As luck would have it, one was seen on May 16th, the same day that the merganser showed near Arenal! The Godwit turned up at the shrimp ponds of Paquera, a town on the shores of the Gulf of Nicoya. Even better, the bird has stayed around long enough for some local birders to tick this excellent addition to their country and life lists. Maybe it will stay a bit longer?

Oilbird on Global Big Day

This intriguing sighting deserves a mention because it was not made at Monteverde during the height of the wet season. Each year, some of these odd nocturnal birds make it to Monteverde and other highland areas but their origin is still a mystery. The fact that the birds on Global Big Day were found near San Vito in May and that they have also been found in that area on previous occasions, supports the idea that the birds may be nesting somewhere near there or in adjacent Panama.

White-chinned Swifts Nesting near Grecia

Thanks to local birder Luis Barrantes, a few of these rare Cypseloides species swifts were found nesting behind a small waterfall above the town of Grecia. Due to near constant difficulties identifying this species, it’s hard to know how many live in Costa Rica and where they actually occur. The fact that some were found nesting in mountains within sight of where I live is a reminder to pay even closer attention to the swifts seen in the skies above the neighborhood.

My best definite image of a White-chinned Swift, kind of how you see them in the field.

As for Team Tyto, we haven’t found anything amazing where we live but we have managed to add a couple of year birds during the past week. One was a Tropical Screech-Owl calling from a nearby coffee farm, the other was Black Swift when several foraged quite low and vocalized just over the apartment. More new birds are still possible, I could for for a Black-billed Cuckoo just out back…

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biodiversity

Global Big Day, 2020, Costa Rica

Global Big Day 2020 was scheduled for May 9th. Despite the birding being limited by variations on a lockdown theme, not only did GBD still take place, but more than 118,000 checklists were submitted to eBird and 6,469 species were identified! It goes to show that even during a global pandemic, birding doesn’t just persist, given the right circumstances, this fantastic nature-connecting hobby can thrive and grow.

Apparently, with so much time available (perhaps combined with a yearning to leave the house) more folks are experiencing the outdoors by watching the closest bit of the wild, that of the backyard. They are looking out their windows and of course, they are seeing birds. Many are no doubt noticing, realizing, that more birds than they ever dreamed of visited their backyards, some hitching up or down tree trunks, others flitting to the feeder or rummaging in the fallen leaves.

Hoffamann’s Woodpecker is a tree hitching backyard bird in Costa Rica.

Just as every birder had a first bird or feathered spark of interest that led them on the road to bird festivals, buying field guides, and comparing optics, some of the people watching birds because of the 2020 quarantines will be following that same route. In Costa Rica, I don’t know how many new birders we will have because of a novel virus but the more the better!

I know that we did have excellent participation for GBD, 2020. Despite restrictions on freedom of movement in Costa Rica (our vehicle wasn’t allowed on the road on May 9th), we had a healthy showing of birders counting in and near their homes, and a few small groups stayed out for most of the day. Some people even managed to look for birds at night and this put most possible nocturnal species onto Costa Rica’s list for GBD, 2020.

Bare-shanked Screech-Owl made it onto the list.

We didn’t have any coast to coast Big Day bird racing nor individual lists that topped 300 species but one collective of birders, Team Northwest, recorded nearly 400 species and Team Turrialba found more than 300. Not bad, not bad at all given closures of national parks and beaches and driving restrictions! High totals by individual birders topped out at 184 for Fernando Barrantes, 181 for Gabriel Rojas, and 181 for David Mora Vargas. All of these high totals are testament to the huge number of bird species that can be encountered in small areas of Costa Rica.

As for Mary and I, we got in some early morning birding at and near our place, took it easy back at the apartment and kept track of whatever other birds we happened to hear or see from the house. I ended up scanning the skies quite a bit to enjoy the show of swifts and Hirundines. One distant Northern Rough-wing Swallow got me wishing that I was seeing a rare for Costa Rica Tree Swallow until it flew closer and swept my hopes away by showing its true dull colors. It was an addition to our GBD list nonetheless and shared aerial space with several Blue-and-white, Cliff, Barn, and Bank Swallows. Looking and listening above also gave us our best bird of the day, a year Spot-fronted Swift that graciously gave up its identity by calling as it flew overhead. The other fortunately calling year bird was an Alder Flycatcher, a species migrating through Costa Rica these days.

Alder Flycatchers may migrate more through the highlands than their Willow counterparts.

Various other regular birds also made it onto our GBD list, birds such as the fancy White-eared Ground-Sparrow, Great Kiskadee, Red-billed Pigeons, a calling Crested Bobwhite, and more species.

In keeping with true GBD fashion, other “regular” birds took the day off and waited until May 10th to call just out the back door. No mention of real names but I will say that the conspirators were a carpintero with lineations and a shrike-like bird that imitates a zebra.

This bird has lineations.
Grant’s or Grevy’s?

May 9th, 2020 wasn’t the most typical of Global Big Days but it still encouraged nearly 50,000 people to count the birds they identified, many of them just outside their respective homes. As for Costa Rica, we still managed a fantastic total, hopefully, we will be able to watch birds from one side of the mountains to the other in October.

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birds to watch for in Costa Rica

The Situation with Yellow-Green Vireos and Related Species in Costa Rica

Vireos are, more or less, these small warblerish, deliberate birds with miniature shrike-like bills. The Vireonidae family also includes the tiny, active greenlets of Central and South America, the small chattering vireos of scrubby habitats (such as the White-eyed and Bell’s Vireos), and the big and hefty shrike-vireos with equally impressive hooked beaks. Lest we leave them out of the Vireo picture, this family also has some colorful representatives in montane zones of southern Asia; the aptly named “shrike-babblers“.

However, the vireos that seem to capture the heart and soul of this avian family are the ones that take it easy, that take their sweet time to forage in the foliage of trees and bushes, constantly singing as they do so. On account of that repeated carefree song, these are the vireos that tend to engender familiarity among birders of all stripes, the leader of the bunch probably being the Red-eyed Vireo.

When spring gets truly warm up north, go birding, take a walk, or just listen in a park in almost any wooded area from eastern Texas and Florida north to the Great Slave Lake and you will probably hear Red-eyed Vireos. Be as patient as the bird you are looking for, watch for the slightest movement in the leafy scene above and you will eventually espy one, a bird with white underparts, olive above, and a white eyebrow separated from a svelte gray crown by a fine line of black. That’s the Red-eyed Vireo, a plain yet clean-cut bird with a sweet June song. Always one of the first migrants I would come across as I rode my bike to experience May migration on Goat Island, I would hear them throughout the day for for the next two months.

In Costa Rica, although thousands, more likely millions, of Red-eyed Vireos that migrate through this part of Central America on a biannual basis, “our” most familiar of the Red-eyed bunch is actually the Yellow-green Vireo. The Red-eyeds don’t sing around here, they barely even act like the summer birds of the north. In Costa Rica, they don’t have any time for that happy, lazy attitude because they have a vital appointment arranged by the imperative of instinct. The destination isn’t exactly just around the corner. To reach the leafy woods of western New York, the forests of Ontario, at just the right time, these small birds have to fuel up fast and in Costa Rica, this is why we see flocks of them busily picking bugs and larvae from the leaves, eating small berries to bulk up so they can take that personal bird express to the north.

They are only here for the eating business, just passing on through until they can get back to regular vireo business, that of casually foraging while singing all day long. In Costa Rica, that vireo job, living “la dolce vireo vita” is held by the Yellow-greens.

Although they also migrate through, large numbers fly in from habitats in the Amazon to stay and breed. As with their Red-eyed cousins of the north, Yellow-green Vireos likewise come to breeding grounds to take advantage of a sudden wealth of invertebrates, in their case, brought on by the onset of the wet season. Like the Red-eyeds, their constant singing is an essential part of the summer birding scene in the Central Valley and the dry forests of the Pacific slope. Unlike the Red-eyeds, they share their breeding surroundings with the likes of Masked Tityras and Clay-colored Thrushes and have to avoid the nest depredation antics of toucans.

They act and look quite similar but with a good view, these two vireo species are pretty easy to identify. Some of the ways in which they differ:

Red-eyed Vireo

-Daintier grayer bill.

-Mostly white underparts.

-Hint of pale brown on face.

Yellow-green Vireo

-Can have somewhat diffuse face pattern.

-Largish, mostly pale bill.

-Lots of yellow below, mostly on vent and flanks.

Although these are two of the most common Vireo genus species in Costa Rica, they aren’t the only similar Red-eyed type vireos to keep in mind. Granted, the following two are very rare and one has yet to be documented for Costa Rica but they are possible. The Black-whiskered occurs as a rare vagrant and is likely overlooked among the large numbers of very similar Red-eyed and Yellow-green Vireos. Although a birder still needs a close, definitive look at the head, a Black-whiskered can also reveal its true identify when it sings its distinctive, double-noted phrases. These can be reminiscent of a House Sparrow, the only problem is that it probably keeps quiet in Costa Rica.

While watching for vireos with a black line on the lower part of the face, we can also challenge ourselves (or drive ourselves crazy) by looking for the Chivi Vireo. Although its name might make you wonder if I’m joking, save the laughs for when you see how ridiculous it would be to find one of these pseudo Red-eyed Vireos, a species that would also be a first for Costa Rica. The Chivi Vireo breeds in South America and because it looks so similar to the Red-eyed, was formerly considered to be that species. Some are resident in northern South America, others migrate from places like Brazil and Argentina to the Amazon and ever since genetic studies showed that they are more closely related to Black-whiskered Vireo than the Red-eyed, Chivi Vireos have been recognized as a distinct species.

BUT, since they look just like Red-eyed Vireos, how on Earth would we even recognize one that just happened to overfly its usual destination? In all likelihood, we wouldn’t, but given the right circumstances, finding one in Costa Rica is possible, this is what we would need:

Look for a Red-eyed Vireo from June to August, this is when a Chivi would mostly likely occur.

Take a close look at the undertail coverts. If it looks like too much yellow for a Red-eyed Vireo, the bird might be a Chivi.

Take a close look at the color of the eye– if it looks pretty dark and without the slightest hint of red, it might be a Chivi.

If it sings, record that song! Both main groups of Chivi Vireos sound different from the Red-eyed Vireo. To my ears, the migrant ones we are most likely to get have a sort of warbled or trilled note.

To sum things up, if you see a bird in Costa Rica between June and August that sort of looks like a hybrid between a Red-eyed Vireo and a Yellow-green Vireo and happens to be a singing a song with a trilled phrase, there’s a fair chance it’s a seriously lost bird new for the Costa Rica list. In the meantime, if birding up north, enjoy the cheerful summer phrasing of the Red-eyed Vireos. Birding in Costa Rica? Be happy with the rainy season songs of Yellow-green Vireos but keep listening and watching for something different, you never know what you might find even when birding from home.