Archive for May, 2020

My 4th Visit to Phinizy Swamp

May 28, 2020

Phinizy Swamp is a protected wetland located in Augusta, Georgia about a 20 minute drive from my house, and if I could, I would visit it more often than I do.  We strolled through the swamp 2 weeks ago for the first time since my daughter almost stepped on an alligator’s head here.  I wasn’t expecting to see as much bird life during late spring because wintering ducks have already migrated north.  However, I did see big flocks of spotted sandpipers (Actitis macularious) and chimney swifts flying over the water, and I also saw a couple of lesser yellowlegs (Tringa flavipes).  The spotted sandpipers and lesser yellowlegs winter south of Augusta and spend their summers farther north.  Both are migratory transient species for this area.  The lesser yellowlegs breeds in Alaska, so these particular individuals were lagging far behind.  Spotted sandpipers breed through much of the Midwest.

2 spotted sandpipers and a lesser yellowlegs.

8 spotted sandpipers, 1 lesser yellowlegs, and a yellow-bellied cooter.

This was the biggest yellow-bellied cooter I’d ever seen.

We encountered a classroom with a professor and students who were studying the macroinvertebrates and water quality of the swamp.  Some of the macroinvertebrates they may have collected were backswimmers, a bug in the Notonectidae family.  These true bugs (Hemiptera) should not be confused with water boatmen of the Corixidae family.  Backswimmers swim on their backs, while water boatmen swim right side up.  Backswimmers are predators that feed upon insects, tadpoles, and minnows; water boatmen feed upon algae.  Surprisingly, both can fly and find isolated puddles where they won’t be eaten by fish. There is a dragonfly in the below photo as well.  Dragonflies are beneficial predators that eat mosquito larva.

Blue dragonfly perched over backswimmers.

The forest around the swamp consists mainly of water oak, loblolly pine, red maple, sweet gum, and cypress.  My favorite trees here, though, are the beech–otherwise rare in Augusta.

A week after I visited the swamp a man posted a photo on facebook of a bald eagle in Phinizy Swamp.  I hope I get to see a bald eagle here on my next visit.

 

The Lujanian Land Mammal Age, the South American Equivalent of the Rancho La Brean Land Mammal Age

May 19, 2020

(Note: I accidentally published this article earlier today before I added the text.  I deleted that mistake. Here is the text.)

The Rancho La Brea Fossil site in California produced so many spectacular fossils that it gives the name to the Rancho La Brean Land Mammal Age, a period of time including the last 300,000 years of the Pleistocene.  All the fauna from this age in North America is referred to as Rancho La Brean.   In South America this age is known as the Lujanian Land Mammal Age and is named after a former site in Lujan, Argentina where fossil hunters found in quality and quantity specimens that are at the very least the equal of those found at Rancho La Brea.   People began collecting fossils here as early as the late 18th century and continued to do so well into the 20th century until the site was swallowed up by urban development.  The Lujanian Land Mammal Age was originally considered to have begun when horses of the equus genus first entered South America, however, paleontologists have since determined equus horses colonized South America much earlier, perhaps over 1 million years ago.  (Horses from the hippidion genus lived in North America even earlier.)  In any case land mammal ages are an artificial construct invented by men to define the composition of fauna that lived during certain periods of time.

Luján | Argentina | Britannica

Location of Lujan, Argentina highlighted in white.

At least 31 species of mammals weighing over 40 pounds lived in and around what is now known as Lujan during the late Pleistocene.  This list includes an astonishing 14 species of xenarthans: 2 large species of armadillos, 7 species of glyptodont, and 5 species of giant ground sloth.  By comparison Rancho La Brea was home to just 3 species of xenarthans.  Ecologists puzzle over how the environment could support such a wide variety of closely related species.  The different species of animals likely ate different species of plants.  The ground sloths Glossotherium and Lestodon were bulk feeders of grass, Mylodon and Scelidotherium were mixed selective feeders, and the huge Megatherium was the most selective feeder of all the sloths.  Similar niche partitioning likely occurred among the large armadillos and glyptodonts.

Doedicurus clavicaudatus

The glyptodont, Doedicurus clavicaudatus.

3 species of primitive ungulates occurred during the Lujanian Age–2 species of toxodon and the bizarre ancient litoptern.  Toxodons were hippo-like in build and may have been semi-aquatic.  Litopterns (Macruachenia patachonica) diverged from the ancestors of horse, tapir, and rhino before the dinosaurs became extinct, yet those odd-toed ungulates are their closest living relatives.

The Toxodon was so weird - Business Insider

Toxodon platensis.

Darwin's dilemma: Bizarre ancient animal identified through DNA

The extinct litoptern, Macrauchenia patachonica.

More modern ungulates ranging near Lujan during the late Pleistocene were 4 species of llamas (3 now extinct), collared peccaries, an extinct species of horse, and a large extinct species of deer (Morenelephus lujanensis.  A mastodon-like gompothere (Stegomastodon platensis) roamed the land with them.

5 large species of carnivores preyed upon the plant-eating beasts.  Smilodon populator, a 750 pound saber-toothed cat, took on and took down some of the megaherbivores.  Jaguars and cougars attacked smaller prey than Smilodon’s victims.  The little known small wolf (Dusicyon avus) may or may not have hunted in packs but was probably more a scavenger, like a coyote.  An extinct bear (Arctotherium tarijensis) opportunistically ate meat whenever it had a chance.

Reference:

Farina, Richard; Sergio Vizcaino and Gerry De Juliis

Megafauna: Giant Beasts of Pleistocene South America

Indiana University Press 2013

 

Squirrel Monkeys (Saimiri oerstedii) and their Co-Horts

May 13, 2020

Several species of birds follow foraging squirrel monkeys through the jungle tree tops of Central and South America.  Troops of squirrel monkeys look for insects and fruit to eat, often overturning leaves and thrashing branches.  Their actions dislodge hiding insects and lizards, and this exposes them to predators.  Double-toothed kites (Harpagus bidentatus) perch on nearby branches, looking for insects or lizards forced to leave their hidden refuges.  Normally, their prey blends in with their surroundings, but the kites are attracted to the exposed prey forced to move.  Gray-headed tanagers (Eucometis pencillata) and tawny-winged woodcreepers (Dendrocineeb anabatina) also find insects this way.  These birds also follow white-throated capuchin monkeys, and they are among the many species that follow army ants. This behavior has occurred for tens of millions of years, ever since monkeys accidentally rafted over from Africa.

Guianan squirrel monkey information from Marwell The Zoo

Squirrel Monkey

Gray-headed Tanager - eBird

Gray-Headed Tanager

Tawny-winged Woodcreeper - eBird

Tawny winged woodcreeper

Double-toothed Kite - eBird

Double-toothed kite

Army ant columns attract even more birds than troops of monkeys do.   Fleeing insects and small vertebrates become prey to a family of 18 species of antbirds known as the Thamnophilidae, as well as cuckoos, thrushes, and chats.  The bird-ant relationship is parasitic.  Studies determined army ants obtain 30% less food when they are followed by antbirds.  It’s not always a beneficial relationship for the birds either.  4 ant stings is all it takes to kill the small birds.

Reference:

Boinski, S.; Peter Scott

“Association of Birds with Monkeys in Costa Rica”

Biotropics 20 (2) 1988

Learning about Mammals of Costa Rica (part 2)

May 7, 2020

I was most interested in learning about squirrels of Costa Rica because they are active during the day and would be the mammal I’d most likely see.  5 species of squirrels occur in Costa Rica, and the 2 most common–the red tailed (Sciurus granatensis) and the variegated (S. variegatoides)–co-exist throughout the country.  On ranges where they co-occur red-tailed squirrels tend to eat harder nuts such as palm nuts and Brazil nuts, while variegated prefer softer food including mangoes, avocadoes, and young coconuts.  Both eat acorns.  Mountain forests in Costa Rica are dominated by oaks, beech, and bamboo; but they are rich environments with many species of tropical trees and vines including palm, coffee, avocado, and figs.

ADW: Sciurus variegatoides: INFORMATION

Variagated squirrels have many different coat patterns.

Squeamish people might cringe at the numerous species of large rodents living in Costa Rica.  Yellow-spined porcupines (Coendou mexicanus) live in the trees, but the large gray Watson’s climbing rat (Tylomys watsoni) occasionally invades homes.  Spiny rats, 7 lb agoutis (Dasyprocta punctata), and 30 lb pacas (Agouti paca) forage on the forest floor.  Pacas are rare because they reportedly taste good and are a frequent target of hunters.

Lowland paca - Wikipedia

Many large rodents, such as this 30 lb paca, live in the jungles of Costa Rica.

3 species of skunks and 4 species of weasels live in Costa Rica.  The 5 lb grison (Calicotis vittosa) and the 10 lb tayra (Eira barbara) tackle large snakes as well as rodents.  7 species from the raccoon family (Procyonidae) occur in Costa Rica.  White-nosed coatis (Nasua nativa) are among the most common, foraging on the forest floor in groups of up to 30.  This family also includes the adorable arboreal kinkajou (Potos flavus) and olingos (Bassarieyon sp.).

Coati Mundi Stock Photos - Download 35 Royalty Free Photos

White-throated coatimundis patrol jungle floors.

Just 2 species of canids occur in Costa Rica (coyote and gray fox), but an astonishing 6 species of cats live there including oncilla (Leopardus tigrina), margay (L. wiedii), ocelot (L. pardalis), jaguarundi (Herpailurus yagaourundi), cougar (Puma concolor), and jaguar (Panthera onca).  I was unaware of the existence of the oncilla until I read this book.  It is arboreal and closely related to the margay.  Jaguarundis are the most common wild cat here because they prefer disturbed habitats and don’t sport a colorful coat coveted by humans.  Jaguars hunt sea turtles on Costa Rican beaches, dragging the 440 lb chelonians into the jungle.  Jaguars have a powerful bite and eat smaller turtles, shell and all.  They eat the exposed head and neck of sea turtles and scoop out the rest with their paws.

Oncilla-Leopardus tigrinus | Animals, Small wild cats, Wild cats

An oncilla.

5 species of ungulates occur in Costa Rica–Baird’s tapir (Tapirus bairdii), white lipped (Tayassu pecari) and collared (Pecari tajacu) peccaries, and red brocket (Mazama americana) and white tailed (Odocoilus virginianus) deer.  White lipped peccaries and Baird’s tapirs are confined to protected areas.

Central American Red Brocket Deer - Encyclopedia of Life

This red brocket deer is particularly red-coated.

The freshwater dolphin (Sotalia fluviatalis), a small species, swims in rivers as far inland as 50 miles in Costa Rica and even further in Brazil.

Reference:

Wainwright, Mark

Mammals of Costa Rica

University of Cornell Press 2006