Costa Rican mammals, part 2 – those quite different from our Carolina wildlife neighbors!

Seeing mammals that we don’t get to enjoy during nature outings in the Carolinas was one of the treats of my Costa Rican trip. Although we spotted spider monkeys during our outings, it was the mantled howler monkey (Alouatta palliata) that we saw – and heard – most often. My first sighting of one was last year, when its white scrotum identified it as a mature male.

These primates eat mostly leaves (50-75% of its food), designating its diet as folivorous (new word for me!).

This low-energy diet means that they sleep and rest a lot – all night and about 75% of the day! They will supplement their leafy meals with fruit and flowers, and they get their water from bromeliads and holes in tree trunks.

Their large hyoid bones amplify the sound coming from their vocal cords so that their calls echo up to 3 miles (5 km) throughout the forest.

Interesting fact: if the howler is disturbed or irritated by humans, it will sometimes urinate or defecate on them, having surprisingly good aim from high in the tree canopy!

Another arboreal mammal that everyone in our group found endearing was the three-toed (brown-throated) sloth (Bradypus variegatus). These animals are apparently quite popular with tourists and often appear in logos and signs. An orphaned sloth was brought to one hotel where we stayed; the staff let the youngster go up in a tree in the courtyard where we could see it.

     

I had seen (and touched) a sloth in a friend’s back yard in Bolivia once (right); seeing another one close-up outside a zoo was a new treat. I love how they move in slow motion. Their sluggish movement is a result of their diet – just like the howler monkeys, they are folivorous and conserve energy as a result of their mostly leafy diet.

 

That slow movement and the fact that they cannot walk on all fours, unfortunately can also be the cause of their undoing. Their movement on the ground consists of dragging themselves forward by their forearms and claws. Our guide told us that when they cross roadways in that position, drivers may not notice them on the pavement until it’s too late to avoid them. ☹

An interesting fact is that their rough hair eventually comes to harbor various organisms, including cockroaches, beetles, moths and algae. So picking them up and holding them is perhaps not advisable – both for the human who can get insects all over them and for the sloth, who can get upset by being held. (The sloth I touched in Bolivia, below, was at the base of a tree and when I put my hand on its chest, it made no movement but I could feel its heart rate suddenly increase rapidly, so I backed off!)

 

Another interesting behavior – once a week, the sloths leave their trees to defecate on the ground. At this time, they become vulnerable to predators. (The sloth in my friends’ yard unfortunately did this and was killed by a neighborhood dog.)

 

On the ground, a slender dark mammal that frequents hotel gardens, people’s yards and nature reserves is the white-nosed coatimundi (Nasua narica). These mammals are related to raccoons and people in Costa Rica will tell you that they are Costa Rican raccoons.

 

Coatis, as they are popularly known, travel both on the ground and in trees, although I only saw one arboreal individual. They usually spend the nights in trees and then come down to look for food, which includes small vertebrates such as mice and lizards, eggs, snakes, insects, carrion and fruit – a varied diet, for sure!

The coati below was busy at the side of a mountain road we walked; it was unclear to me what it was doing. There was obviously another animal there and at first, I thought it was a young coati, but I don’t think that was the case. I now wonder if another mammal had died and the coati was investigating it as a food source.

 

They do not appear to be very wary of humans; this one passed by fairly close in a wooded area. Apparently, people will feed coatis strawberries along roadsides, which will undoubtedly make them less wary of humans. This coati might have been a male as they are solitary except for mating season when they will join a female group for a time.

Another ground-dwelling mammal we saw on multiple occasions in different areas was the Central American agouti (Dasyprocta punctata). This rodent plays an important role in the forest as it is a seed disperser. Like squirrels, the agoutis bury caches of seeds and nuts for lean times; when they do not re-visit a storage area, the seeds and nuts may germinate to create new trees.

 

The agoutis eat other foods as well, including leaves, roots and fruit. They will sit on their hind legs and hold the food in their front paws to dine.

These cute animals mate for life; the young are unusual in that they are active right after birth. The mother takes them to nest sites dug by other animals so they can claim their own home burrows! The young then line their home with leaves and twigs.

It is worth noting here that the Costa Ricans are protecting their ground mammals and all other wildlife. The country was the first in Latin America to ban sport hunting in 2012; it is also forbidden to keep, import or export wildlife for the pet trade.

And finally we get to the smallest mammals we viewed during our August trip. Last year, our group had been surprised to find that a group of bats was flying into a hotel’s outdoor restaurant to roost each night. The staff accommodated the creatures, which they listed as two-lined bats. After reading about Costa Rican bats, I think these might be lesser white-lined bats (Saccopteryx leptura). It was interesting to see how they would hang by one leg as they engaged in some grooming.

This year, we came across a small group of similar-looking bats roosting under a bridge. They had white lines down their backs but appeared to be long-nosed proboscis bats (Rhynchonyceteris naso). Their colonies often number 5-10 individuals.

One of our most interesting walks took place the day after our bridge sighting. We were visiting a self-taught local artist named Cope, in La Union, Guapiles. He created a wildlife viewing site around his home where he welcomes tourists to see hummingbirds and other avians. He offered to take us into the nearby forest to find a particular owl (coming blog!), as well as a couple species of bats and some interesting amphibians.

While we may be used to thinking of bats living in caverns, various species in the rain forest have found other roosting sites. The tent-making bats (Uroderma bilobatum) create a home by biting through the middle vein of a large leaf so that the sides droop down and form a hanging shelter. The structure is recognizable and after Cope found us a couple tents, members of our group knelt or hunkered down so we could peer upwards at the sheltering mammals.

 

At one site, after photographing the bats, I unfortunately stumbled backwards after taking a photo; I startled the bats, who took off in haste. Apparently, it is known that they spook easily since the slightest movement of their leaf could indicate that a predator is approaching. Cope fortunately located another tent so that the other group members could peer upwards at the creatures.

Our guide was kind enough to use people’s cell phones to take photos of the little bats.

At another tent, it turned out that adorable Honduran white bats (Ectophylla alba) were roosting. Of the approximately 1300 known bat species, only six have entirely white fur.

These bats are frugivorous, with one fig species being a preferred food.

The Honduran white bats are unique in being able to convert lutein into a form that better helps protect the retina and it is speculated that understanding how they do this could be helpful in the treatment of macular degeneration.

Our final bat species had a different type of residence – a termite mound, which may be abandoned or actively harboring termites. I believe that the species we saw was the pygmy round-eared bat (Lophostoma brasiliense), an insectivore although it will also eat fruit. Their daytime roosting site is maintained by a resident male bat, who prevents termites from repairing the cavity made by the bats. Seeing these nocturnal mammals in an unexpected home was truly an interesting way to conclude our bat-watching outing.

 

Many thanks to Nan DeWire and Ylva Byars for letting me include photos they took in this blog. After a foray into North Carolinian wildlife in the next posting, it will be back to Costa Rica to take a look at the woodpeckers there – and elsewhere!