Birding in Costa Rica #14: Hiking on the Osa Peninsula

A King Vulture soaring overhead

As I mentioned in my last post, we spent quite a bit of time in Osa hiking. Well, maybe walking is a better description. Or, maybe slowly walking and standing still a lot to view birds and wildlife. 

We were there to see birds, not to break speed records (whew!)

Whatever ...

During our time there, we took an afternoon hike to the BioStation and then on to the seashore. Earlier, Heather had asked if we could go to the beach to swim and Nito said he wouldn't recommend it because of currents.

A beautiful shore on a beautiful day

When we got to the shore, we saw that it was obviously better suited to viewing than water sports. It was rocky with waves crashing against the volcanic rocks that jutted into the ocean. 

Then, on the day we had no van, we took two hikes, a morning in the nearby jungle and an afternoon where we made our way to old-growth forest and, I think, into Corcovado National Park. That day, we hiked about six miles.

Most of the trails were fairly level, although there was some up-and-down when we went to ocean. 

Osa Vista

The trails were wide and easy to follow, but covered in leaves and lots of roots just trying to grab your feet and throw you to the ground. With all the leaves, I was certain we'd see some snakes, but we didn't. Nito had seen a Fer-de-Lance (one of the world's most poisonous snakes) the first night, so we were on alert.

Part of our hikes was on the road

Plus, we were still concerned about Ants, although Bullet Ants are not as common on Osa as in La Selva.

In addition to my camera, I took a walking stick and that was a good idea.

The vegetation was thick, but obviously immature near the BioStation. That area is regrowth reclaiming old ranches and farms that had deforested parts of the Peninsula. 

The far end of one hike was pristine, old-growth jungle that was, obviously, more stately with lots of huge, gnarly trees.

So, did all this walking in the oppressive heat and humidly yield anything? Oh, yes!

Birds

It seems that one of the most common Osa jungle birds are Woodcreepers, which are endemic to the Neotropics. Related to Ovenbirds, they tend to be rather large, ranging from 5 to 14 inches long . The ones we saw were all shades of brown, with varying streaks, bars or spots, generally on their heads and napes.

A Northern Barred Woodcreeper ... well, creeping

Woodcreepers feed mainly on insects taken from tree trunks. They have long, stiff tails that actually support most of their body weight; a bird that loses its tail usually has difficulty climbing. Woodcreepers climb by flexing their legs and hopping up the trunk. Their front toes are strongly clawed and toe IV is as long as toe III to increase the ability of the bird to grasp around branches.

Here, we saw Black-striped ...

The most social of all the Woodcreepers we saw

... Cocoa, Northern Barred, Tawny-winged, Streak-headed, Plain Xenops and Wedge-billed ...

Cocoa, Northern Barred and Tawny-winged; I didn't get a photo of the last three on Osa

I had captured the Plain Xenops and Streak-headed Woodcreeper earlier on our trip ...

Streaked Woodcreeper at Avaro's and Plain Xenops in Carara National park

A similar sized and colored but unrelated bird was the striking Rufous Piha ... 

A large jungle bird

This bird is actually a Cotinga, which means it is a cousin of the Three-wattled Bellbird.

In the bushes, we saw a nice assortment of small-to-medium-sized birds, including Tanagers, Flycatchers, Greenlets, Woodpeckers and Warblers ...

CW: Chestnut-sided Warbler, Cinnamon Woodpecker, Scarlet-rumped Tanager, Tawny-crowned Greenlet, Great Crested Flycatcher, White-throated Shrike-Tanager, White-Shouldered Tanager, Streaked Flycatcher

And, we saw a lovely female Black-throated Trogon ...

Not as colorful as her mate, but pretty

When we were in the open area of the BioStation (where we could actually see the sky), we saw lots of birds circling so, so high up they could barely be seen with binoculars. This included Gray-breasted Martins, Costa Rican Swifts, White-collared Swifts and Turkey and Black Vultures. 

But, one we did see fairly close was a magnificent King Vulture ...

A bird that we had hoped to see

Photo: Osa Conservation

A very large bird, the King Vulture has a wingspan that can reach 7 feet.

Predominantly white, it has gray to black ruff, flight and tail feathers. The head and neck are bare with red and purple skin on the head, vivid orange on the neck and yellow on the throat. The colors can vary.

The head is wrinkled and folded and there is an irregular golden crest attached on the cere above the orange and black bill.

A scavenger, the King Vulture often displaces smaller Vulture species from a carcass, which may be how it earned its status as "King. " Or the name may be a reference to Mayan legends in which the bird was a king who served as a messenger between humans and the gods.

The King Vulture soars for hours effortlessly, flapping its wings infrequently. While in flight, its wings are held flat with slightly raised tips and, from a distance, it can appear to be headless. 

It is non-migratory and, unlike the Turkey, Lesser Yellow-headed and American Black Vulture, it usually lives alone or in small family groups. One or two birds generally descend to feed at a carcass, although occasionally up to ten or so may gather if there is significant amount of food.

Soaring overhead

Principally a carrion eater, it consumes anything from cattle carcasses to beached fish and dead lizards. 

The King Vulture has no voice box, but it can make low croaking noises and wheezing sounds that it uses in courtship. It snaps its bill loudly when threatened. 

The King Vulture's only natural predators are snakes, which will prey upon the vulture's eggs and young, and large cats such as Jaguars, which may surprise and kill an adult vulture at a carcass.

Although currently listed as Least Concern, they are decreasing in number, due primarily to habitat loss. The one we saw had a transmitter on its back (in fact our Osa presenter told us they had just placed the transmitters the day before as part of the Ridge to Reef project).

When I really zoomed in, I saw it

Another great sighting for the BioStation was a gorgeous swallow-tailed Kite ...

Magnificent

I had seen some in Florida a few years ago and missed a shot and then seen another one earlier in the trip and missed again, so getting the photo was extra sweet.

On our hikes, we didn't see many raptors other than Vultures and the Kite, except one Common Black Hawk perched in a palm tree on the beach ...

Just surveying his domain

Every jungle hike involves searching for tiny little (and usually colorful and entertaining) Manakins. Osa delivered with a female Blued-crowned Manakin ...

Male Manakins go through elaborate courtships to attract these cute females

... and a male Orange-collared Manakin ...

Such a poser!

We even got video of the latter ... 

Army Ants and What They Bring

I mentioned earlier that our guide, Nito, was enamored of Army Ants. Indeed, these interesting creatures were his pathway to his profession.

Army Ants at work

As we were hiking through the jungle and, no matter how hard we tried not to, making considerable noise walking through the deep leaf cover, Nito suddenly stopped and said, "I hear Army Ants approaching." Of course, I heard nothing. But, we waited, and eventually, we started to see advance columns of Ants, a wide variety terrified bugs (Roaches, Crickets, Flies) leaping from the jungle floor to escape the Ants.

Working cooperatively

The name Army Ant is actually applied to more than 200 Ant species in different lineages in the world and Costa Rica has 600 different species of Ants in general; I do not know what type these were.

But, the main characteristic of Army Ants is that they constantly undertake raids in the jungle, killing and taking home insects and small animals. Their main prey are the nests of other ants whose eggs and larvae they steal to feed on their own offspring. 

Opportunistic birds take advantage by following the swarm and picking off insects that try to escape.

Nito said birds would come and they did

Almost blind, Army Ants rely on their sense of smell to find and track prey. They don't build nests, instead bivouacking for a night to several weeks in hollow logs or underground.

They carry heavy loads

Because they voraciously devour Scorpions, other Ants and Cockroaches, Costa Ricans call them "limpiadores," which means "cleaners" in English.

These Ants are taking out the garbage

A colony of Army Ants can consume up to 500,000 prey animals each day, including ground-dwelling arthropods and their larvae, earthworms and occasionally also the young of vertebrates, turtle eggs or oily seeds. A majority of the species, the "colony robbers," specialize in the offspring of other Ants and Wasps.

When Army Ants forage, the trails that are formed can be over 66 feet wide and over 330 feet long. They stay on the path through the use of a concentration gradient of pheromones. The concentration of pheromone is highest in the middle of the trail, splitting the trail into two distinct regions: an area with high concentration and two areas with low concentrations of pheromones. The outbound Ants will occupy the outer two lanes and the returning Ants will occupy the central lane.

We watched them move along and then came the reward, the birds that follow (and eat) the ants and the bugs they chase (to eat). This included the adorable little Bicolored Antbird ...

Those eyes stand out

And, some Black-hooded Antshrikes ...

Left, female; Right, male Black-hooded Antshrike

Later, we saw another ant-eater, the Streak-chested Antpitta ...

The cutest bird in Costa Rica

This bird actually looks like the embodiment of a child's drawing of a bird ...

The Army Ants weren't what I expected, because the Ants did not arrive en masse, instead they moved in columns underneath the ground cover. It's amazing that, moving under the leaves like that, they didn't make more noise.

The didn't look as organized as I expected, but I am sure they had a plan

Of course, we saw lots of bugs, most tiny and fleeing for their lives. But, in the course of our hike, we did encounter a beautiful orange Leaf-footed bug ...

It was hard to see in the flower, but then it jumped

... and Butterflies ...

A Postman Butterfly and a Sister Butterfly

... and an assortment of Wasps ... 

There were huge Warrior Wasp nests everywhere

... and whatever these are ...

Bees? Wasps? Termites? I don't know

I have been trying to ID the above nest, which blends perfectly with the tree. They look like bees, but there is a Termite tunnel running beside the hive.

Animals

Although we never saw any Jaguars, Tapirs or Anteaters, we did see a few more White-nosed Coatis and Agoutis rustling through the jungle, plus a Collared Peccary that crossed the path right beside us as we were watching the Army Ants ...

You may know this as a Javelina

Plus, we encountered a troop of curious Geoffrey's Spider Monkeys ... 

Monkeys had become common sightings

You will recall, I talked about Spider Monkeys in an earlier post.

Look at that adorable face

Best Bird: Scarlet Macaw

But, our best encounter on our hikes was close and long-lasting. When we reached the beach, we found a gorgeous Scarlet Macaw eating Beach Almonds, an introduced plant that Macaws have adopted as a favorite food. 

One of Costa Rica's most iconic birds

Our presence didn't faze it a bit. It was too busy chowing down.

One hungry bird

This one was alone; most of the Macaws we saw were in pairs (most likely with its life-mate) or in fast-flying groups.

A pair flying over the Lodge

This large red, yellow and blue Parrot is common throughout Costa Rica, despite suffering from habitat destruction and the pet trade.

Close-up detail

An adult Scarlet Macaw is almost 32 inches long.

A very large Parrot

More half is the Macaw's pointed, graduated tail ...

An impressive tail

As impressive as its size is its lifespan. The Scarlet Macaw can live up to 90 years in captivity, although a more typical lifespan is 40 to 50 years.

Showing off its colors

Scarlet Macaws are vocal, making raucous squawks, squeaks and screams designed to carry great distances to call for their groups. 

Captive Macaws are known to be adept mimics of human speech.

They feed on fruits, nuts, seeds, flowers, nectar, insects and larvae, snails and foliage. Macaws also eat clay, although why isn't known. That heavy bill is an incredibly effective nutcracker, as the debris below the feeding sites demonstrates. 

Beach Almond shells

And, they have a scaly tongue that can reach in to grab out the nut meat. There is actually a bone in the tongue that helps with this. 

We really enjoyed getting to know this beautiful bird. See a video here.

Macaws actually sleep about 12 hours a day

Of course, there were more birds, but I promised I wouldn't bore you with "the ones that got away."

Next up: Some driving tours of the Osa Peninsula.

Trip date: March 9-27, 2022