Saturday, December 31, 2016

2016's Top 10 Birds

The year 2017 is almost here and we are eager to receive it, full of hopes of better days to come and, in my case, wishing for life birds.  That could be a quite ambitious wish, since 2016 was pretty exceptional regarding new birds species for my Panama Life List!  This year, that is about to end, brought to me 15 amazing lifers plus many range-restricted rarities and even some potential splits.  To choose only ten of them was hard task... I took into consideration rarity, relevance for Panama and the region, beauty and general circumstances of the sighting.
Purple-throated Mountain-Gem (Cerro Hoya)
10. Purple-throated Mountain-Gem (Cerro Hoya): although strictly talking this species was not a lifer, the truth is that the whole experience of climbing Cerro Hoya, in southern Azuero Peninsula, was amazing.  Remote, little explored and full of range-restricted forms, Cerro Hoya probably holds new species for science and this hummingbird certainly is one of those.  The main differences with other forms of this species is the tawny belly and the green, non-iridescencent forecrown.
Typical Coiba Island landscape
09. Coiba Spinetail: endemic to Panama and restricted to the larger island in the Pacific Ocean of Central America, the Coiba Spinetail was the last endemic I had to see in my country.  That day, the Coiba Spinetail was the first of three life birds for the day, the most productive day of the year regarding lifers, but I was unable to get a photo... a nice excuse to return to that paradise island!
Black-billed Cuckoo
08. Black-billed Cuckoo:  nothing is easier than waiting for the life birds to come to you!  And last september 30th, this Black-billed Cuckoo just showed up right in front of my balcony!  Yes! It was a lifer, a long-expected one by the way.
Cave Swallow
07. Cave Swallow: this extremely rare vagrant to Panama was the only migrant swallow present that November 1st in Finca Bayano (to the east of Panama City) aside of the abundant Barn Swallows.  It was just the 6th record for the country, and another addition to the long list of rarities occuring at Finca Bayano this year... a site that proved exceptional regarding rarities.
Unspotted Saw-whet Owl
06. Unspotted Saw-whet Owl: this rare owl was re-discovered just three years ago in the upper slopes of the highest mountain of Panama, the Baru Volcano.  Thanks to the growing group of Boquete birders, it was regularly recorded this year... the twitch reunited fine birdwatchers, including the top three birders for Panama (according to eBird) and it was a complete success!
Arctic Tern
05. Arctic Tern: while visiting a completely new site for me, the Islas Secas Archipelago off the coast of Chiriqui province in the Pacific slope of western Panama, this little fellow allowed nice views and conclusive photos... documentation was important because it was just the forth record for Panama!
Hudsonian Godwits
04. Hudsonian Godwit: the third ever recorded Hudsonian Godwit for Panama showed up in Finca Bayano this fall and the news spread like fire!  The very same day I saw my life Cave Swallow, the pair of juveniles godwits decided to feed in the open, proving to be an awesome lifer!
Green-winged Teals
03. Green-winged Teal: a pair of Green-winged Teals were my last lifer of 2016.  Again, Finca Bayano proved spectacular, I was looking for a Northern Pintail reported elsewhere (also rare) when I noticed these birds at flight.  Just the third record for Panama, and the first photos for the country!
Black Noddy
02. Black Noddy: identified while reviewing the photos after the pelagic trip off the coast of western Azuero last December 4th, this Black Noddy was the second report for Panama and the first one documented with photos, thus it is not longer in the list of hypothetical species for Panama.
01. Sharp-tailed Sandpiper: I know you already suspected it... not only a life bird... a HUGE one; but also a new species for Panama and Central America!  This Asian breeder is regular in some parts of North America, and this is only the second record south of the United States of America.  Definitively the rarest of the long list of rarities in Finca Bayano!

I wish to thanks all the birders and friends that accompanied me this year and that helped me to find all these spectacular birds!  Next year will be even better!  HAPPY NEW YEAR 2017!!!

Tuesday, December 27, 2016

GT turns five!

Our precious Gabrielle Teresa (GT as we like to call her) is now a young 5 years-old lady, full of life and surprises... yes, is that age when they ask why for everything and each day learn something new.  The celebration started yesterday... we decided to stay in a thematic hotel room in Panama City with her  cousin Analia.  Can you guess the theme?
We did not think that two girls could have so much fun!  Welcome gifts, costumes and dresses, room service, swimming pool, and all the dolls and accesories they can dream of!  Today, after the check-out, it was time for the official birthday party at one of her favorite spot: "Mi Princesa" Fantasy & Beauty. It was an afternoon filled with fun and excitement with family and friends, and Gabrielle enjoyed it so much!
Happy Birthday Gabrielle! Mom and dad love you so much!!!

Friday, December 23, 2016

More surprises at Finca Bayano

I guess that, at this point, you already know that Finca Bayano (the rice farm to the east of Panama City) is a terrific place for birdwatching.  Not only quantities, but also quality is present at this site... so far, many rare and very rare species have been recorded... including a new species for Panama!  I thought that the rarity season ended with the fall migration, and had not visited the site in a few weeks... until my friend Euclides "Kilo" Campos reported a VERY rare (for Panama) Northern Pintail... so I decided to pay a visit.
We have been so many times in Finca Bayano this year that it was easy for Kilo to give me the exact location of the observation ... he just had to tell me "the Roseate Spoonbill's spot" and that's it!  So, I drove directly to the site last December 11th , finding the pond pictured above.  At first glance, no ducks were on the water, but eventually I realized that there were scattered groups hiding in the rice at the farther edge of the pond.  I walked along a dry dike in order to get closer to take some photographs... but as usual, the ducks became very nervous when I approached them.
Blue-winged Teals, Stilt Sandpipers and Long-billed Dowitchers
I approached them enough to take the above shots... As you can see, those Blue-winged Teals were mixed with Stilt Sandpipers and two Long-billed Dowitchers.  Then, I noticed other ducks well hidden in the rice.  These birds were larger than the teals, with obvious bigger bills: Northern Shovelers.  The shovelers are scarce, but regular, winter visitor to our country.
Northern Shoveler
I checked them carefully looking for the pintail, but I just found more teals and shovelers instead.  When I started my way back, a huge flock of teals took off from the rice fields.  I was not aware they were hidden in such numbers in the rice... dozens of bird suddenly started to fly from one side to another.  For my surprise, one of the teals looked suspiciously pale in the underside... when I found it with my binoculars I watched the bright green speculum and the lack of pale blue wing coverts... I barely trusted my eyes!
Blue-winged and Green-winged Teals
Blue-winged and Green-winged Teals
Not one, but two Green-winged Teals were present within the flock... GREEN-WINGED TEALS!!!!  Why so excited?  That was just the third record for Panama... and the first photos of the species for the country!  Ohh... and a life bird for me as well!!!  What a HUGE surprise for the site.  Thanks God the photos show well the birds... they are fast flyers, with sudden shifts and turns, and hard to follow with the lens.  Four days later, I went back to the site... this time with my friend Kilo.  His careful scrutiny with the scope resulted in finding both birds at the edge of the same pond... they were life birds for him as well!
Digiscoped Green-winged Teal
After much searching, we were not able to find the pintail... but who is complaining?  Finca Bayano is still full of surprises.  Interestingly, we have not yet found the rare rallids we expected to find when we started visiting the rice farm... we thought at first that Finca Bayano would be full of rails and crakes... but so far, only common species have been recorded... and not so often.  However, as a nice bonus, this Sora decided to show up attracted by our recorded calls... it is a common species seldom seen this well.
So, what are you waiting for? You may be the next discoverer of a mega rarity, or even a new species for Panama, at Finca Bayano!

Friday, December 16, 2016

At the roof of Panama

The Chiriqui province, in the Pacific slope of western Panama, offers the most accessible sites to birdwatch the Talamanca highlands and all its array of endemic species, and thus, is a popular destination for national and international organized birding tours.  However, few people ventures to its highest peak, the Baru volcano, with its 3.475 meters above sea level, in order to find the specialties restricted to the highest slopes. 
Paramo near the summit of Baru volcano
The high elevation vegetation and the paramo at the summit of the volcano are unique in Panama, and is protected by the Volcan Barú National Park.  Other similar habitats are essentially unaccessible in our country.  The seriously deteriorated, pot-holed and irregular road to the summit start at the charming town of Boquete, but only highly modified vehicles  can make it to the top... it is a bumpy ride, but is better than walk the 14 km-long road to the top (if you start at the rangers station).  But apart of witnessing awesome landscapes and to experience the sight of both the Pacific and Atlantic Ocean from the top, why else do you want to climb that high?  For the birds of course!  Some exciting findings at the upper slopes of the volcano came to light in the last months by the growing community of Boquete birders, including Rafael Velasquez and Jason Lara. That's why we contacted them to arrange a trip up there some weeks ago... and by "we" I mean Osvaldo Quintero, Rafael Luck, Euclides "Kilo" Campos, Darién Montañez and your host of course.
male Volcano -Heliotrope-throated- Hummingbird
We left Boquete aboard two huge trucks and started the ride around 2:00 pm.  I can swear that it felt like the vehicle was climbing a ladder!  Our first birding stop on route was at the crater known as Potrero Mulato, just above the 3.000 meters.  The birds up there where distinctively different to those found in lower slopes: Large-footed Finch, Sooty-capped Chlorospingus, Black-capped Flycatcher, Fiery-throated  and, aptly named, Volcano Hummingbirds started to be common sights... even a Costa Rican Pygmy-Owl responded to our tapes in the distance; however, these were not the birds we were looking for... so we kept climbing.
Black-capped Flycatcher
Eventually we reached Los Fogones campsite, at 3.260 meters. The vegetation looked pretty much like the paramo in the first photo, but with taller trees.  It was Volcano Hummingbirds' heaven... we even found a female on a nest. and several males displaying.  We fail to locate one of our "secondary" targets: Volcano Junco.  Although disappointed, it did not hurt as much because the species would not be lifer for me.  More than ten years ago, I climbed the volcano with a group of friends following the path in the opposite side of the mountain.  It was strenuous, rained all day and we almost froze at night while camping near the summit... but in the bright side, a flock of Volcano Juncos (and some Sooty Thrushes) decided to feed mere six feet from me while I was still trying to warm myself in front of an improvised campfire with the first rays of the sun.  I was alone in the campsite... and I clearly remember that while I was seeing the juncos, the phrase "with birds I'll share this lonely view" rumbled in my head... mountain sickness?  Hypothermia?  Who knows... I just remember the birds in the paramo.  In conclusion: not, it would not be a lifer for me.  But the bird that Jason was attracting with a recorded tape would... soon, a Timberline Wren started to sing around us, keeping low in the bushes and allowing some nice, but short glimpses.
Timberline Wren
What a bird!  Beautiful, smart, sonorous, range and habitat restricted... and a lifer!  So far so good!  However, it was not our main target (believe it or not).  Near sunset, we reached the summit of the sleeping volcano.  We like to think in Panama that our highest peak is extinct; but is not, although it last eruption was in the 16th century and the lava flow and debris avalanche reached as far as the Pacific Ocean (ten times the area covered by the Mount St. Helens debris avalanche in 1980!).  Back then, the lateral eruption melted the perpetual snows that covered the summit, collapsing it.  Now there is no snow left... but for this sun-lover of Panama City, the 8º Celsius temperature up there was freezing cold!
Sunset at the summit of Baru volcano
Well, the Rufous-collared Sparrows and the Sooty Thrushes seemed well adapted to the dropping temperatures at the summit.  In fact, both species were quite common and active... I just was thinking on keep warm.  The birds even were actively feeding at dark after sunset... those small silhouettes in the dark hoping around felt weird.
Sooty Thrush
We took dinner after sunset and started to descend in complete darkness.  The skills of our drivers were impressive... dodging huge boulders and tilting the car almost 45 degrees from side to side to fit into narrow corridors... it was scary and exciting at the same time.  Around 3.130 meters, Raul made us to stop in the road.  It was about 7:20 pm and completely dark due to the waning crescent moon... but the clear skies let us watch the stars, a rare sight up there.  He carefully chose a patch of forest with open windows (areas free of foliage) hoping to attract our main target into to one of them in order to have unobstructive views.    We took our positions behind Raul, with spotlights and cameras ready... he then played the tape at full volume once... a response was heard almost immediately!  He then played the tape at very low volume and waited... an UNSPOTTED SAW-WHET OWL started to call very close to us!
Unspotted Saw-whet Owl
We realized that the bird was below eye-level... but it quickly flew to a higher perch (right to one of those "windows") where we managed to spotlight it... and I was able to take the photos of this post.  What a sublime experience! That is a species considered extremely rare... probably it just passed unnoticed all this time due to its high elevation habitat... thanks to the fluorishing community of Boquete birders now we know a little bit more about this rare owl. The first photos from Panama were taken just this year by Raul and Miguel Siu, and the bird was re-discovered just three years ago when Jason Fidorra and Lena Ware managed to record and see a bird close to Los Fogones campsite.
Unspotted Saw-whet Owl

At the end, we heard at least three different individuals.  There were lots of high-fives and hurrays! Mission accomplished!  A little after the birds left the site, it began to rain, and we continued our descent to Boquete, where we celebrated with a round of cold beers.  Those were many emotions for a single day ... and the owl's calls were still in my head at bedtime... but I still had one day left in Boquete and did not think about wasting it... so I fell asleep to recharge batteries with the vivid memory of the rarest and cutest owl without spots!  Tomorrow would be another day... and other story, so stay tuned!

Wednesday, December 14, 2016

2016's Last Pelagic Trip Off Western Azuero Peninsula

Pelagic trips are always exciting off Panama coasts.  The pelagic avifauna is so poorly known that effectively no one knows what to expect.  That's why I try to attend every pelagic trip I can... and this trip was not the exception!  My friend Kees Groenendijk, of Heliconia Inn B&B, organized everything, as he has did in the last trips.  He and his wife, Loes Roos, have become real experts in the logistics of these special trips, and I highly recommend them if you plan a visit to that area.
Alfred, Howard, Rolando, Kees, Mikko and Jan Axel
This time, the companions willing to brave the waves, endure the weather conditions, withstand the odor of fish viscera that we use as bait and to ignore the seasickness were Alfred Raab, Howard Laidlaw, Rolando Jordan and Mikko Oivukka.  Kees, as usual, was our guide and in charge of the chumming process (thanks God).  We left Reina beach, close to the town of Mariato, just before dawn.  Watching the sunrise from the deck of the boat was magical.
We did the same route we followed in previous pelagic trips (you can read about them here and here) and the sea was relatively calm in spite of the dark clouds in the horizon.  After reaching Punta Naranjo (Azuero's southwestern corner), we headed directly to the south, to the Continental Shelf break and into deep waters.  At this point, we had only seen common inshore species, except for a jaeger that passed swiftly that we were unable to ID to species.  At the Continental Shelf break, we started to use the chum to attract our first tubenose... a Galapagos Shearwater.
Galapagos Shearwater
This species is regular in Panamanian offshore waters, although the numbers seem to fluctuate each season, we only saw a few of them this time.  The only other tubenose seen in this trip was a Wedge-tailed Shearwater that we were unable to photograph, but was easily ID'd since we had some experience with that species in Panama from the pelagic trips from eastern Azuero.  More interesting was the completely lack of storm-petrels in these waters... they certainly were not there!  We also saw another pelagic species... not a tubenose, but a pair of elegant Sabine's Gulls.
Sabine's Gulls
What a good sight!  The bird with the black terminal band in the tail and brown upperparts is a juvenile; while the other bird is an adult in basic plumage. The conspicuous wing pattern was unmistakable even at long distances.  We recorded at least five individuals of these graceful gulls.  After several hours, we started to head towards mainland.  In the way, we crossed some non-avian highlights.  First, a pod of 20 or may be 30 Short-finned Pilot Whales that stayed with us for more than 30 minutes.
Short-tailed Pilot Whales
spyhopping Short-finned Pilot Whale
Then, an Indo-Pacific Sailfish decided to feed at the surface very close to our boat... it was a lifer for me!  In fact, my first billfish ever!  Amazing!  Curiously, No one on board showed even the slightest interest in catching the fish... such a magnificent beast is better enjoyed free at the sea.
Indo-Pacific Sailfish
In the way to port, we decided to check a seamount known by local fishermen as a good spot for fishing.  As soon as we got there, a flock of Common and Black Terns welcomed us feeding over a school of Bonitos... it was a feeding frenzy.
Black and Common Terns
However, we noticed a different bird with them... in fact, someone mentioned that a "black" bird was feeding close to the surface.  We immediately identified it as a  noddy... certainly a Brown Noddy, the expected and common species in the area... it was a little bit dark to feel comfortable, but what else could it be?  I took several photos, most of them blurry shots...
Black Noddy
Black Noddy
The photos show a dark bird with uniform upper and under wing patterns, a contrasting white crown and forehead and slightly grayer tail; but most important, it has a thin, long bill... a Black Noddy!!!  We saw this bird several time feeding with the terns... you can compare it relative size in the next photo.
Black Noddy with Common and Black Terns
Then, we found a Brown Noddy in a different flock... the bird was evidently "brown" in the field, not black, and the photos show the shorter and stouter bill, the pale bar in the upper wing with contrasting dark flight feathers and the paler underwing.
Brown Noddy
Brown Noddy
The Black Noddy was considered hypothetical for Panama due to a sight record from Islas Frailes many years ago.  These photos confirm the species for Panamanian waters.  The species is not totally unexpected since it is regularly found in waters around Cocos and Malpelo Islands off the coasts of Costa Rica and Colombia respectively.  It was a life bird for me of course, and a great way to end a nice pelagic trip off western Azuero Peninsula!

Saturday, November 26, 2016

A Record-breaking day!

And for a second year in a row, a world birder visits our isthmus in his quest to record the largest number of birds species in a year.  Arjan Dwarshius' attempt to break the world's big year record of 6042 species recorded in a year, set by Noah Strycker just 11 months ago, was about to make history!  After spending his first day in Panama last November 3rd, Arjan was just 11 birds away of the record!  This was not coincidence... Arjan and, his uncle Fred, chose the local advantage to make the most of their time in our country... they were guided by Guido Berguido who runs Advantage Tours and who is the head of the local NGO ADOPTA Panama Rainforest... and also an old, good friend of mine!  Also joining them was another friend of mine, birder extraordinaire and, since recently, an excellent, independent birding guide Ismael "Nando" Quiroz.
Elfin forest at Cerro Jefe, above Cerro Azul (file photo)
I took the late night bus from Penonome town (about two hours from Panama City), where I was resting with my family during the holidays (yes, the first days of November are holidays in Panama), in order to join the group in the record-breaking day!  Very early the next day, we headed to the gated community of Cerro Azul in the foothills to the east of Panama City, and headed directly to the upper slopes of Cerro Jefe and its stunning elfin forest, home of many range-restricted birds.  The day started quite low, but with some new year-birds for Arjan.  At the Vistamares trail we crossed a mixed flock with Shining and Green Honeycreepers, Rufous-winged, Emerald, Speckled and Black-and-yellow Tanagers, migrant Red-eyed Vireos, Tawny-capped, Fulvous-vented and White-vented Euphonias, Paltry Tyrannulets and White-ruffed Manakins, among others.
Black-and-Yellow Tanager (male)
After a while, Guido managed to attract an endemic Stripe-cheeked Woodpecker allowing scoped views... but the desired Black-crowned Pittasoma refused to show up...  but a pair of handsome Yellow-eared Toucanets were a nice consolation price instead.  Eventually, we managed to find 10 new birds for Arjan's list.  Year-bird 6042 was the Black-eared Wood-Quail that we actually managed to see thanks to Nando's advice (it was a life bird for me; although I have heard it several times previously).  After that, the activity dropped sharply... and we decided to have lunch before heading to Calle Maipo trail.
Yellow-eared Toucanet (male)
At Maipo, the record-breaking bird arrived quite unexpectedly when a Tody Motmot (very rare in the area) responded to a recorded call played by Guido... we tried hard to see the bird but it turned out to be very shy... but we saw a pair of Crimson-bellied Woodpecker that were Panama lifers for me as well (not a new year-bird for Arjan of course).  After realizing that we were not going to see the bird, we accepted that the record-breaking species was a heard-only record... of course, lots of high-fives, big smiles and congratulations continued!  Uncle Fred surprised all of us (including Arjan) when he opened a Champaign bottle and a nice banner to celebrate the moment... I'm impressed of his organization!
He did it!
We ended the day at the-now-famous Finca Bayano, were we managed to find the Long-billed Dowitchers reported earlier in the season... they were new year-birds for him, as well as three other species in spite of the short time we spent there.  And in spite of the short time I shared with Arjan, I can tell that he is passionate about birds and birding... he really seemed to be enjoying each little brown job that, desperately, we were pointing to him hoping it to be a new year-bird for him... but what can you show to a man that already has seen more than 60% of the extant birds of the world! I recommend you to track his progress HERE... the numbers are just amazing!  Not only that, remember that he is birding as a fundraiser for the BirdLife Preventing Extinctions Programme , so enter the webpage and make a donation!  I had to said good bye after leaving Finca Bayano... a long journey back with my family was awaiting me.  He spent five more days in Panama, watching amazing birds in Chucanti, Nusagandi, Yaviza, Aligandi and even right here in Panama City before taking his flight to Costa Rica.  Check this POST and you'll see that he is VERY lucky as well! 
FAREWELL, MY FRIEND.... I know 7000 birds for this year is plausible!

Tuesday, November 22, 2016

ID of Dowitchers in Panama

Until some time ago, identifying wintering dowitchers in Panama was pretty straight forward... only Short-billed Dowitchers were expected in this country at any habitat since Long-billed Dowitcher is very rare and expected to winter south only to northern Central America; however, some records exist from Panama.  The problem is precisely our assumption that any dowitcher seen in Panama is a Short-billed Dowitcher, and so far the most important publications on birds of Panama have a cautionary note that both status and distribution of Long-billed Dowitcher in Panama are uncertain due to difficulty of identification.  Nonetheless, more and more Long-billed Dowitchers have been recorded in Panama, specially this fall with great numbers recorded already.  How good are you identifying dowitchers?  Try with this bird:
Dowitcher sp. Panama Viejo, Panama. November 13th, 2016
Dowitcher sp. Panama Viejo, Panama. November 13th, 2016
I took the above pictures in the coastal mudflats of Panama Viejo, in Panama City.  As usual, I assumed it was a silent Short-billed Dowitcher in almost complete basic plumage (some retained alternate feathers in the back and scapulars).  The best way to separate both species is by voice... but if your bird is silent (as it usually happens in Panama), what field marks are you going to look for? The first thing to do when you try to ID these birds is aging them, because it is easier to separate juveniles of both species than adults in basic (non-breeding) plumage.  With our country well into the usual winter range of Short-billed Dowitchers (and way to the south of that of Long-billed Dowitchers), we will certainly find juvenile birds molting into basic plumage.  It doesn't matter how advanced in molt they could be, since most of them retain at least some juvenile feathers until January (including the characteristics tertials feathers).  In general, juvenile Short-billed Dowitchers have dark-brown upperparts feathers with broad golden-buff fringes and variable internal markings, particularly in the tertials (given them the typical "tiger-striped" look), and dark brown crowns that contrast with the white superciliums.   Underparts whitish with buff-brown wash, slightly brown-streaked upper breast, sparse spotting and barring on flanks and undertail coverts.
Juvenile Short-billed Dowitcher. Juan Diaz, Panama. November 4th, 2010.  Dark crown, retained juvenile greater coverts, diagnostic retained "tiger-striped" tertial feather.
Juvenile Short-billed Dowitcher. Panama Viejo, Panama. November 12th, 2016.  Dark crown, retained juvenile greater coverts and scapulars, diagnostic retained "tiger-striped" tertial feather.  Also notice shape and structural differences (see text).
Juvenile Long-billed Dowitchers are darker above, with only thinner and duller buff fringes to scapular and tertial feathers, the latter almost lacking any internal mark.  Juvenal greater coverts are uniform gray.  Compared to Short-billed Dowitchers, Long-billeds' crown is grayer with slightly less contrast with the rest of the plumage.  The underparts are very similar to those of juvenile Short-billed Dowitcher.
Juvenile Long-billed Dowitchers. Finca Bayano, Panama. November 10th, 2016.  Gray crown, retained scapular feathers with just buff fringes (almost no internal markings) and retained tertial feathers with just thin buffy fringe.
Our mystery bird lack any retained juvenile-patterned feather, making it an adult bird.  Separating basic plumaged birds of these two species used to be considered an impossible task... a task that we have to deal with in Panama on a daily basis, specially now that we know that Long-billed Dowitcher can occur in great numbers as well.  Several papers on identification can be found on-line.  Most of them describe plumage differences, but differences in structure, shape and habitat are useful too, although structure and shape differences varies among populations, age and sex, even within a same species.   I'll illustrate some of these differences with the next two photos of an adult Long-billed Dowitcher and a juvenile Short-billed Dowitcher (same photo posted above):
Adult Long-billed Dowitchers. Finca Bayano, Panama. November 10th, 2016.  Straight, thin-based bill, slight indentation at the back, big-chested look with attenuated rear, wingtips doesn't reach the tail tip
Juvenile Short-billed Dowitcher. Panama Viejo, Panama. November 12th, 2016.  Notice bill shape, more oval-shaped bodywith no indentation at the back, rotund rear and wingtips reaching tip of the tail.
The length of the bill (as their name suggests) is useful to differentiate females Long-billeds and males Short-billeds.  But more important, notice the difference in shape, with Long-billed Dowitchers having very straight bills while Short-billed Dowitcher shows a slightly downcurved tip, that looks kinked, as if the bird had left the tip of the beak trapped when a door was closed.  Also, bill of Short-billed Dowitcher tend to be more wide-based and blunt-tipped than the thin-based and pointed bill of Long-billed Dowitcher.  Body shape also differ, with Long-billed Dowitcher having a deep-chested look and shorter wings, thus attenuating the rear of the bird that often look with cocked tail; different to the more oval-shaped and horizontally oriented body shape of Short-billed Dowitcher that have longer wings, with wingtips usually reaching the tail tip or beyond (thus looking with more rotund rear).  Long-billed Dowitchers are also longer legged, an useful field mark to detect lonely birds among a flock of Short-billed Dowitchers.  Again, all of these structural differences varies depending on sex, age and population, and not only on species, but can be useful when inspecting a distant flock of dowitchers or under bad light conditions to see plumage field marks.
Adult Long-billed Dowitchers (ID by voice). Las Macanas marsh, Herrera. January 28th, 2011.  Notice bill length and shape
One field mark that is proving to be quite reliable is the loral angle given a direct profile view.  This is the angle between an imaginary extension of the gape of the bill toward the back of the head and the line connecting the gape of the bill with the center of the bird's iris.  A diagram probably explains it better:
Close-ups of previously posted photos.  Long-billed Dowitcher, above, showing a more acute (smaller) loral angle than Short-billed Dowitcher (below)
This angle reflects differences in facial expression, forehead shape and relative position of the eye between these two species.  As you c an see, Long-billed Dowitchers have more acute (smaller) loral angles than Short-billed Dowitcher.  Ok.  I have to admit that all the differences mentioned so far are quite difficult to asses in the field, but take into consideration that you need several field marks, instead of an unique and definitive feature, to ID correctly basic-plumaged dowitchers in Panama.  Once you are used to these differences, then you can compare the plumages of these both species.  Starting with the most common, basic adult Short-billed Dowitcher tend to be paler than Long-billeds, with patched gray breast that doesn't contrast strongly with the white belly and setting a more conspicuous white throat, and spotted and chevroned (instead of barred) flanks that are paler than in Long-billed Dowitcher.
Adult Short-billed Dowitchers. Panama Viejo, Panama. November 4th, 2010.  Pale and patched gray breast making little contrast with belly, pale and plain backs, chevroned (not evidently barred) flanks.  Notice also body and bill shapes.
Adult Long-billed Dowitcher. Finca Bayano, Panama. November 10th, 2016. Dark and solid gray breast contrasting with belly, barred and contrasting dark flanks, inconspicuous white on throat.
Notice that the back feathers in Long-billed Dowitcher have dark centers explaining the uniformly scaled and darker look than in Short-billed Dowitchers (with plainer, paler backs).  Also notice the white-fringed coverts feathers in Short-billed Dowitcher (vs brown-fringed in Long-billed Dowitcher).  At flight, the lesser coverts in the underwing of Long-billed Dowitchers are white with no bars (barred in Short-billeds), a field mark seldom noticed.
Adult Long-billed Dowitcher. Finca Bayano, Panama. November1st, 2016. White lesser underwing coverts diagnostic. 
The tail pattern is partially useful in Panama where the three subspecies of Short-billed Dowitcher occur... both caurinus and hendersoni show variability in tail feather patterns.   Now, back to our mystery bird:
Dowitcher sp. Panama Viejo, Panama. November 13th, 2016
Dowitcher sp. Panama Viejo, Panama. November 13th, 2016
When I reviewed the photos, it was the tail feathers pattern that caught my attention.  It seemed that this bird had wider black bars than white ones, consistent with Long-billed Dowitcher; however, as I mentioned earlier, it doesn't seem to be useful in Panama as a unique field mark to ID this bird.  Other field marks are covert feathers fringed in white, patched gray breast, pale flanks and back (although it looks faintly scaled), white throat and open loral angle... all of them suggestive of Short-billed Dowitcher.  Other structural differences are not evident in these photos (except long wingtips).  Last clue is habitat.  This bird was recorded in coastal mudflats, an habitat where Long-billed Dowitchers have never been recorded in Panama; however, take into consideration that the fresh water/salt water habitat preferences described for Long-billed and Short-billed Dowitcher is vague... Short-billed is fairly common in fresh water habitats inland in Panama, while there is at least one record of Long-billed Dowitchers in coastal saltflats (as in Aguadulce, central Panama).
Adults Short-billed Dowitchers. Juan Diaz, Panama. October 8th, 2010
I'm not discussing differences in alternate plumage because it is seen for a short period of time in Panama, but I encourage you to study about them in order to adequately document the different populations that winters in Panama.  Take these alternate plumaged hendersoni Short-billed Dowitchers for example:
Alternate adults Short-billed Dowitchers (ssp. hendersoni). Aguadulce salinas, Cocle. August 5th, 2016.
Well, there is a lot to study and to reveal about these two species in Panama... is time to grab your bins and to get some dowitchers to ID!
Literature consulted:
1. Ridgely R, Gwynne J. A guide to the birds of Panama. Princeton University Press; 1989.
2. Chandler RJ. Dowitcher identification and ageing. A photographic review. Brit Birds 1998; 91: 93-106.
3. Lee C, Birch A. Advances in the field identification of North American dowitchers. Birding 2006; sept/oct: 34-42.
4. Angehr G, Dean R. The birds of Panama. A field guide. Zona Tropical; 2010.
4. Karlson K. kevin's id tips: Long-billed and Short-billed Dowitchers. Available at