Learning about Mammals of Costa Rica (part 1)

A few years ago, I fantasized the U.S. exiled me.  I chose Costa Rica over Canada as my new country of residence because of the more pleasant climate.  I even went so far as to search for a Costa Rican house online, and I found a nice 1 for $90,000–the equivalent value of my actual house (property values in Richmond County, Georgia are much lower compared to those of most of the rest of the country).  The ad for the house mentioned monkeys and coatis in the back yard.  For my birthday this year, I purchased a copy of The Mammals of Costa Rica to learn about what animals I might see, if the U.S. ever exiles me.  There are many species I never even heard of or only knew about vaguely.

8 species of opossums live in Costa Rica.  The Virginia opossum (Didelphis virginiana) reaches the southern limits of its range in Costa Rica, but a similar species (D. marsupialis) takes its place further south.  The woolly opossum (Caluromys derbianus) lives in trees and are monkey-like with large brains, forward setting eyes, and prehensile tails.  There are 2 species each of 4-eyed opossums and mouse opossums.  Perhaps the most interesting opossum species is the yapok (Chironectes minimus), an aquatic mammal that feeds upon crustaceans, frogs, fish, and insects.  It has a water-tight pouch to protect its young when it swims, and the young have a low metabolism, so they can survive without much oxygen for a long time.

A water opossum.

7 species of edentates or xenarthans occur in Costa Rica.  The brown three-toed sloth (Bradypus variagatus) and Hoffman’s two-toed sloth (Choelupus hoffmani) evolved their arboreal lifestyles from 2 completely different ancestral families of extinct ground sloths.  (See: https://markgelbart.wordpress.com/2015/01/08/choloepus-tree-sloths-are-closely-related-to-the-largest-extinct-ground-sloths/ ) Biologists believe tree sloths make up the most abundant biomass of any mammals in the region.  This is impressive considering their slow rate of reproduction.  2 species of tree anteaters occupy different niches.  The northern tamandua (Tamandua mexicana) feeds upon ants and termites on the main trunks and larger branches.  They use their large claws to quickly break opens nests and consume insects before too many fiercely armed soldiers show up in defense.  The much lighter silky anteaster (Cyclopes didactylus) feeds upon ants and termites on the outer branches by using a claw to deftly slice open plant stems.  There is little overlap in the species of insects each anteater feeds upon.

A northern tamandua.

Silky anteater.  

At least 109 species of bats fly around Costa Rica–almost double the number found in the U.S. and Canada combined.  Included among the sac-winged bats is the ghost bat (Diclidurius albus), a strikingly white creature.  There are also mustached bats, nectar-feeding bats, fruit bats, tiny disk-winged bats, and tent-making bats.  The latter actively make tents from large leaves to keep them dry and sheltered when they rest.  Free-tailed bats don’t occur in colonies as large as those found north of the border. Costa Rica is home to bats familiar to us in the U.S. including myotis and red bats, though they are different species.  But many species are unique.  False vampire bats (Vampyrum spectrum) are predators that kill rodents, birds, lizards, and other bats.  The related frog-eating bat (Trachops cirrhosus) specializes in preying upon frogs and locates them by pinpointing their calls.  True vampire bats (Desmodontinae) do feed on blood.  The fishing bats (Noctilio sp.) really catch minnow-sized fish and will carry them in their cheek pouches.

Greater fishing bat.

4 species of monkeys range across Costa Rica.  Noisy howler monkeys (Alouata paliuru) are the most common.  They evolved to subsist on a diet of mostly leaves, though they eat some fruit.  The largest monkey in Costa Rica, the spider monkey (Atelis geoffoyi), mostly eats fruit but eats some leaves.  It weighs up to 15 lbs.  Squirrel monkeys (Scimmiri ocrstedis) are ominivores that are currently less common because of the pet trade.  The most intelligent monkey is the white-throated capuchin (Cebus capuceaus).  They use tools and have been observed using wooden sticks to kill venomous snakes.  They hunt birds and rodents and will knock squirrels to the ground and tear them apart.  Fruit and other plant foods make up a larger part of their diet, however.  They also use medicinal plants, often rubbing them all over their bodies.

White throated capuchin monkey.

Reference:

Wainright, Mark

The Mammals of Costa Rica

University of Cornell Press 2007

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The Co-Existence of Feral Hogs and Peccaries in the Americas

An old episode of Anthony Bourdain’s No Reservations sparked my interest in Brazil’s Pantanal region.  Bourdain searched eastern Brazil in vain for a rare species of fish he wanted to eat.  He was told it was still abundant in a remote part of western Brazil, so he purchased a charter flight to take him there and satisfy his culinary curiosity. The pilot flew the small aircraft through storms, and Bourdain and his crew weren’t sure they were going to make it.  Then, after arrival, Bourdain suffered the worst back pain he’d ever felt, and his producer fell ill with a tropical fever.  Nevertheless, they continued filming and I was impressed with the quantity and quality of wildlife.  It reminded me of 18th century descriptions of Kentucky and early 19th century accounts of Oklahoma.  On a boardwalk through a jungle Bourdain saw a red monkey that no one could identify.  Though there are riverine forests, most of the Pantanal consists of vast treeless plains, variously flooded here and there.  The indigenous people who sparsely populate the Pantanal use it as pastureland, and large herds of feral hogs and peccaries intermingle with cattle.  Caimans and capybaras abound in the flooded parts, and huge flocks of wading birds crowd the water holes.  Incidentally, Bourdain did get to sample the fish.

Map of Brazil’s pantanal.

The Brazilian Panatanal is 1 of the richest wildernesses left on earth.  It encompasses 75,000 square miles and includes at least 12 different types of ecosystems.  463 species of birds, 209 species of fish, and 236 species of mammals live in the region.  It has the healthiest population of jaguars in the world.  Peccaries and wild pigs are the most common ungulates.

Feral hog and vultures feeding upon a dead cow in Brazil’s pantanal region.

Collared peccary.

White lipped peccaries.

Peccaries and pigs are superficially similar in appearance, but they are separated by over 25 million years of evolution.  There are 2 species of peccaries native to the Pantanal–the aggressive white-lipped (Tayassu pecari) and the collared (Pecari tajacu).  Feral hogs (Sus scrofa) are not native to the Pantanal and were introduced hundreds of years ago.  Scientists who study the interrelationships between peccaries and pigs expect the latter to be detrimental to the former, but their studies find this is not true.  A recent study examined the consumption of 37 plant foods among the 3 species, and they found minimal dietary overlap.  Feral hogs favored grugru palm nuts (Acrocomia aculeata), collared peccaries preferred bay cedar (Guazuma sp.), and white-lipped peccaries liked the fruit of a plant in the coffee family (Alibertia sessilis).  All 3 species did feed upon the fruit of Astralea phaleratata, a type of palm.  Palm nuts taste coconut-like.  There was more overlap in diet between white-lipped peccaries and wild hogs than between collared peccaries and wild hogs.  Collared peccaries foraged at times when they could avoid pigs and white-lipped peccaries.

Chart showing diet overlap between the 3 species.  From the below referenced paper.

Palm nuts from the grugru palm are the favorite food of feral hogs in the Pantanal.

Alibertia sessilis fruit ( relative of coffee)  is the favorite food of the white-lipped peccary in this region.

The study determined bay cedar was the favorite food of the collared peccary.

During the Pleistocene new species of mammals periodically crossed the Bering Land Bridge and invaded the Americas, and vice versa.  Like pigs and peccaries, many of the co-existed.  Deer, bear, and big cats came from Eurasia.  Horses and camels went from the Americas to Eurasia.  Co-existence was not always permanent.  Felids from Eurasia outcompeted many species of canids, a group of carnivores originating in North America.  Deer from Eurasia outlasted 3-toed American horses.  The composition of mammals on both continents changed over time, and co-existence between species can be temporary or long lasting.

Reference:

Galetti, M. ; et al

“Diet Overlap and Foraging Activity Between Feral Pigs and Native Peccaries in the Pantanal”

PLOS ONE 2015

 

Pleistocene Phoebes (Sayornis sp.)

I frequently hear the call of the eastern phoebe (Sayornis phoebe), but I almost never see them.  So I was excited to photo a phoebe in my backyard last week.  My cat unsuccessfully stalked it while it was perched in a peach tree.  The bird landed on my fence, then picked off an insect on the ground and returned to the fence and ate it.  This is typical foraging behavior for phoebes.  They look for insects from above and drop to the ground to catch them.  Its mate observed this action from an higher limb.

Eastern phoebe on my fence.

https://www.allaboutbirds.org/guide/Eastern_Phoebe/sounds

Call of an eastern phoebe.

Phoebes belong to the tyrant flycatcher family or the Tyrannidae.  They are named for their aggressive behavior toward large predatory birds such as hawks and owls.  Phoebes mercilessly harass the larger birds until they leave the vicinity of the phoebe’s territory.  Phoebes live year round in my neighborhood–I hear their calls as early as February.  This species expands its range north during summer, and they do the reverse during winter.  They produce 2 broods per summer.  Although they prefer insects, they can subsist on berries and seeds when cold temperatures knock back insect activity.

There are 2 western species of phoebes–the black phoebe (S. nigricans) and Say’s phoebe (S. saya).  A common ancestor of all 3 species likely occurred all across North America about 5 million years ago.  Ecological changes associated with glacial/interglacial climate phases separated ancestral populations of eastern phoebes from their western cousins.  The same is true for a long list of bird species in North America.  There are eastern and western species of scrub jays, nuthatches, flickers, and many others.  Pleistocene-aged fossils of eastern phoebes have been excavated from Kingston Saltpeter Cave in Georgia, Bell Cave in Alabama, Natural Chimneys in Virginia, and Cheek Bend Cave in Tennessee.  Phoebes like to nest on natural or manmade structures, and caves provide favorable nesting locations, explaining why their fossil remains are often found in them.

Eastern phoebe range map.  Say’s phoebes occur almost exactly to the west of eastern phoebes.  Black phoebes are primarily a Mexican species.

There are 2 other species of tyrant flycatchers that occur or are supposed to occur in my neighborhood.  I often see eastern kingbirds (Tyrannus tyrannus), though I never hear them (the opposite of my experience with eastern phoebes).  Fossil evidence of eastern kingbirds has been found at 2 sites in Florida–Reddick and Vero Beach.  I’ve never seen a crested flycatcher (Myiarchus crista), perhaps because they prefer deep virgin forest where they can nest in hollow trees.

Spirit Creek State Forest and Wildlife Management Area in Richmond County, Georgia

The fascist germaphobes closed all the parks in my area, but we were able to find a nice place for a nature walk anyway.  The Spirit Creek State Forest and Wildlife Management Area covers about a square mile in south Richmond County, Georgia.  It’s the former site of farmland used to produce food for Gracewood State Hospital and School.  The former opened in 1921 when many people still relied on their own food production.  Later, it was leased as pasture to cattle farmers before state foresters converted it to a state forest and wildlife management area where hunters can shoot deer, turkey, squirrel, rabbit, and waterfowl.  Some areas are designated for archers, and turkey can only be killed with bows or shotguns.  Oddly enough, hunting for feral hogs and coyotes is not allowed here.

Map of Spirit Creek State Forest and WMA.

Spirit Creek, a tributary of the Savannah River, flows through this protected area.  Marcum Branch and Middle Fork Creek originate near the Columbia County/ Richmond County line, and they join to form Spirit Creek, and the tributary is dammed upstream from Spirit Creek Forest to form Gordon Lake–a golf course water trap.  On our nature walk we journeyed down a gravel road and butterflies led the way.  Seemingly, the same butterfly, a dark phase of a tiger swallowtail butterfly, flitted ahead the entire way, as if it wanted to show us a beautiful scene that made the trip worthwhile.  I saw several species of butterflies including a black swallowtail and a small brown skipper that wouldn’t stay still for identification.  I also observed the regular phase of tiger swallowtails.  I heard cardinals, a tufted titmouse, Carolina wrens, and mockingbirds; but I heard and saw more species of birds in my backyard earlier that morning. I spotted a gray squirrel and deer prints were a common sight on the gravel road.

The forest is species poor.  Originally, this location was likely a rich bottomland forest along the creek and a typical piedmont oak-hickory-pine forest on the hills.  Now, it consists mostly of planted loblolly and shortleaf pines.  Supposedly, longleaf pine grows here, but I didn’t find any.  The only oaks were some overcup oak saplings.  Black cherry and sweetgum are common here.  Birds distribute cherry pits in their droppings, and cherry trees thrive in the open conditions.  I did encounter 2 interesting plants–a sourwood tree and a tobacco plant.  Sourwood normally grows in rich hardwood forests and this specimen stood out in the otherwise monotonous woods.  The poisonous nicotine in tobacco deters most animals from eating it.  Nevertheless, the larva of 17 species of butterflies and moths feed upon it, making them in turn toxic or bad tasting for birds.  Tobacco is native to North America and was cultivated by Native Americans, though I wonder if this particular plant occurs here naturally or descends from a tobacco patch planted a long time ago. Spirit Creek Forest is regularly logged, and evidence of logging is all around.  I took a photo of a logged over section, but it’s so ugly I’m not even going to show it here.

Here’s an unexpected plant–tobacco (Nicotiana sp.).

Spirit Creek State Forest used to be a cow pasture..

Dark phase of a tiger swallowtail butterfly. It seemed like this butterfly led us down a half mile of the trail to show us the waterfall.

At the end of the trail we found what I imagine the butterfly was showing us–a beautiful little waterfall.  It was only 18 inches high, and I suppose a naysayer could call it a rapid but I prefer to have a more enthusiastic attitude.  Our nature walk was a welcome diversion from being quarantined.  We had the whole forest to ourselves.

Surprise.  I wasn’t expecting the waterfall.  Maybe less than 24 inches tall, but I’m calling it a waterfall.

View up Spirit Creek.

There are more rapids up Spirit Creek.

The picnic tables next to the waterfall need repair.  I found an empty beer bottle and an abandoned college textbook here.

Hippos in Colombia

I like to watch the Neflix series, Narcos, but I’m always disappointed in the ending of the story arcs.  The series chronicles the real story of the Colombian drug cartel.  The drug kingpins ingeniously avoid capture for most of the season until DEA agents eventually capture or kill them in the season finale.  This disappoints me because I root for the cartel.  These supposed bad guys are providing a product that people want, and that makes them heroes in my opinion. It’s the law enforcement agents who aim to ruin everyone’s fun.  The first 2 seasons featured the infamous Pablo Escobar, a man elected to Colombia’s parliament but was not allowed to take his seat due to his massive illegal drug operation.  (Decades of Civil War could have been avoided, if he had been allowed to serve in the legislature.) Pablo gave tens of millions of pesos to poor peasants–more than the Colombian government did.  Unfortunately, during 1993, American DEA agents murdered him.

Pablo Escobar.  Why do U.S. taxpayers pay the government to murder citizens in 3rd world countries?

Pablo Escobar loved animals and had his own private zoo.  Following his death, hippos from his zoo escaped into the wild and they are flourishing.  From a founding population of 4 the hippos in Colombia have increased to between 80-100, and biologists predict it could reach between 400-500 or possibly even 5,000 by the year 2050.  Hippos begin bearing young at 3 years of age and can keep giving birth every 2-3 years until they die between the ages of 40-50.  Adult hippos, even in Africa, have almost no natural predators other than man.  (Lions, with difficulty, can kill juvenile hippos.)

Hippos in Colombia.

Some researchers fear hippos, as an invasive species not native to South America, may be detrimental to the Colombian environment.  Concentrations of hippos can foul non-flowing water holes with excessive manure that turns them anoxic.  The concentrated nitrogen leads to algal overgrowth, resulting in water with no dissolved oxygen in it–killing all the fish.  However, other scientists think hippos may be filling an ecological niche formerly held by extinct Pleistocene megafauna and maybe  in some ways beneficial to the environment.  Hippos in Colombia inhabit floodplain lakes, cattle tanks, and streams.  75% of their range has been man-modified into farmland including cow pastures and palm oil plantations while the balance consists of the original tropical forest. In some areas, especially where the water flows, hippo manure fertilizes aquatic plants and increases fish and insect populations.  This means more food for birds.  Hippo wallowing and movement breaks up thick vegetation, and their aquatic trails connect ponds, allowing fish to migrate and colonize new areas.  Their close cropping of streamside vegetation creates lawn-like habitats that attract some species of birds.

Hippos may be a modern day substitute for the Pleistocene haplomastodons that used to occur in this part of South America.  Haplomastodons, a species of gompothere, were probably semi-aquatic. North American mastodons definitely were semi-aquatic–they ate aquatic plants and had fur similar to that of otters and beavers.  Some notoungulates endemic to South America may have also been semi-aquatic, but not enough is known about them to determine this for sure.

Illustration of a haplomastodon.  Fossils of this species have been found in Colombia.

Hippos are in Colombia to stay.  Years ago, some government jerks with a stick up their ass decided to start eliminating the hippos, and they killed a male popular with the locals and tourists.  The outrage among most Colombians put a stop to this.  Animal rights groups sued, and there are now no plans to wipe them out.

References:

Subalusky, A; et al

“Potential Ecological and Socio-Economic Efforts of a Novel Megaherbivore Introduction: The Hippopotamus in Colombia.”

Oryx December 2019

Svenning, J., and Soren Faulby

“Pre-historic and Historic Baselines for Trophic Rewilding in the Neotropics”

Perspectives in Ecology and Conservation 15 (4) 2017