Here's a surprising thing: The ancestors of whales were land-based walking animals that fell in love with water. In the ensuing 50 million years successive species spent more and more time at sea, eventually lost their legs, and now resemble fish. (No, they aren't fish. They just resemble them.)
How did they change from land to sea? To solve the mystery, paleontologists closely examined the fossil record looking for the one trait that only whales have: the unique bony structure of the whale's inner ear. A fossil found in 1981 provided the missing link.
Shown below are two of the whale's ancestral relatives. Not direct ancestors, the diagram shows where those two fit on the family tree. Whales are labelled #1. Animal #2 looks like a dog. #3 looks like a whale.
The change from species to species was incredibly slow.
If we could go back in time 50 million years to the Early Eocene we'd meet Pakicetus inachus (#2), below. First discovered in Pakistan in 1981, he looks like a long-headed dog but he has the whale's special inner ear. Scientists hypothesize that he lived on land but spent time up to his eyes in water hiding from predators.
Fast forward 10 million years to the Late Eocene to see Dorudon atrax (#3), an ancestral whale that spent his entire life in water. His body was fish-shaped, his tail had flukes, and since he never walked his hind legs were small, almost an afterthought.
From "the fish walked" to the walker that became fish-like, whales turn our misconceptions about evolution on their head. Evolution doesn't "make progress" from simple water-based organisms to us land-based humans at the pinnacle of development. It's just any change over time.
Last week coyotes made a splash in my Pittsburgh neighborhood when one appeared in early October. Frank Gottlieb mentioned his sighting on Nextdoor, Luanne Lavelle photographed one behind her house (above) and Crystal Barry zoomed in on this one at the edge of the road (below). It may be the same animal moving around.
Have coyotes suddenly arrived in the city? Are they something we should worry about? No and no. Here's their fascinating story.
Eastern coyotes (Canis latrans) look like gray to reddish-brown husky dogs though they are smaller, have a different head shape, and never curl up their tails. About a third larger than western coyotes, the eastern species weighs 35 to 55 pounds from the smallest female to the largest male.
The eastern coyotes' appearance, size, and presence in Pennsylvania are all human-induced traits caused by our actions toward wild canines and the landscape.
Humans eradicated wolves, mountain lions and deer from Pennsylvania by the late 1800's. Coyotes don't do well where wolves are in charge but during the low ebb of both populations coyotes and wolves hybridized in Ontario resulting in a larger animal with a wider range of prey.
Meanwhile Pennsylvania reintroduced deer whose population soared by the 1930s, expanding to suburbs and cities 60 years later. Wolves and mountain lions did not come back to Pennsylvania but eastern coyotes moved into the deer-eating niche. Coyotes came to Pennsylvania in the 1930s and covered the state by the 1990s.
When did coyotes enter Pittsburgh city limits? I heard of one in 2003; probably not the first.
Why do we see coyotes in October? Fall is the time of year when coyote families disperse. The young, full size at 9 months old, move away and hunt alone in fall and winter then pair up at two years old to raise a family. Smart coyotes hide from humans but some young ones haven't learned that lesson yet.
Are coyotes dangerous? Not to us humans but myths abound, apparently borrowed from our myths about wolves. No, coyotes won't eat your kids. No, coyotes won't lure your big dog away to eat him. (Coyotes play with big dogs (video). Their DNA is 10% domestic dog.) No, coyotes will not stay away from your neighborhood if you remove the one you've seen. (New coyotes will arrive to take its place.)
However, coyotes will take a small pet if it looks easy to do. If you're really worried about coyotes, here's how to discourage them from visiting your yard:
Don't leave any food outdoors. Enclose your garbage. Don't leave pet food out. Don't feed any wildlife. If you attract mice or rats (bird seed), rodents will attract coyotes.
Watch your small dog when you let it out in the backyard. Keep your cat indoors.
If you see a coyote, shout and wave your arms. Shoo it away. Don't try to befriend a coyote. Keep them wild.
Coyotes are smart and our pressure against them makes them smarter. Appreciate them from afar.
As cold weather approaches squirrels in the genus Sciurus -- the tree squirrels -- are scurrying to store food for the winter. Here are two Sciurus you'll see in Pittsburgh.
The eastern gray squirrel (Sciurus carolinensis) is fond of nuts, especially those in bird feeders. In autumn he turns from brown to gray so he'll continue to blend in with the landscape. He also comes in black.
The fox squirrel (Sciurus niger) is larger than the gray squirrel. Though his scientific name means "black" he sports a foxy colored coat all year long, especially on his belly.
Barely larger than chipmunks, the red squirrels (Tamiasciurus hudsonicus) are busy too. Cute but not true Sciurus, they're Tamiasciurus.
NOT found in Pittsburgh I had to include this fancy squirrel, a Sciurus with big ear tufts that lives in the mountains of Arizona, New Mexico and Colorado. Sciurus aberti, Abert's squirrel.
(photo credits: eastern gray squirrel in gray by Marcy Cunkelman, eastern gray squirrel in black by Kate St. John, red squirrel by Chuck Tague, Abert's squirrel by Tom Benson, Creative Commons license on Flickr)
At this time of year an eerie sound echoes through the north woods of Pennsylvania, the mating song of the elk.
In September and October Pennsylvania's elk herd (Cervus canadensis) has an annual period of sexual activity called the rut. The bulls gather harems, pursue the females, spar with other males, and "sing" a bugling love song.
Based on the size and posture of a bugling elk you'd think his voice is low -- but not at all. The bugle call is bell-like and echoing even when the animal is close by. His song carries far in the woods and fields.
Listen and watch the video below to hear the elks' eerie mating song.
For the past two mornings I've heard wild things screaming in my backyard at 5am. It's two hours before sunrise. What are those weird sounds?
Raccoons! And they're fighting!
I didn't go outdoors to record them but I found two videos that include the sounds -- above in Toronto, below on someone's roof.
Why are raccoons fighting in my backyard? I believe it's the watering hole effect. It's been very dry in Pittsburgh so my birdbath is one of the few sources of water. All the animals come for a drink before their bedtime and BAM!
A word to the wise: Don't go outdoors to visit the raccoons. They may have rabies.
(videos from YouTube; click on the YouTube logo on each one to see its original)
Last week four of us hiked the Redbank Trail near Lawsonham, Pennsylvania. At our turnaround point we stopped at a picnic shelter and lean-to that had a new pit toilet restroom with a shiny green door. As I left the restroom I noticed tooth marks on the doorknob.
Then I noticed tooth marks all along the bottom of the door and even at the top. See the red arrows.
The animal apparently propped its upper teeth against the edges and scraped with its bottom teeth.
It scraped the hinges.
And it ate the aluminum door jamb!
Who did this? What Pennsylvania wild animal eats outhouses and chews metal?
Years ago Pennsylvania's porcupines only lived north of I-80 but for more than a decade they've been expanding their range southward. When they reach Pittsburgh they're going to find a lot of doorknobs. 😉
p.s. Porcupines are already south of Pittsburgh in the Appalachian Mountains of Maryland but they prefer to live in heavily forested areas. I can't imagine them moving into cities ... but you never know.
p.p.s. See the comments. Porcupines have been seen in the metro area. Uh oh!
These species tolerate each other at the feeder but their relationship is rocky elsewhere.
In Donna Memon's backyard two curve-billed thrashers wanted this round-tailed ground squirrel to step away from the mealworms. Though they poked her she wouldn't leave. This squirrel is so feisty that she chased a roadrunner!
Away from the feeders it's all out war. Ground squirrels raid bird nests to eat eggs and nestlings.
Curve-billed thrashers try to avoid predation by nesting in cholla cactus.
Steve Valasek found an occupied nest at Hassayampa River Preserve northwest of Phoenix.
Safe from ground squirrels, heat is the big problem at the cactus nest sites.
How do the chicks fledge? Very carefully!
curve-billed thrashers with ground squirrel by Donna Memon
cholla cactus photo from Wikimedia Commons; click on the image to see the original.
curve-billed thrashers' nest by Steve Valasek)
Their ancestors swapped continents during the Great American Interchange. They now live a world away from their country of origin.
The "Great American Interchange" sounds like a flea market or a swap meet but it's actually the movement of species between North and South America when the two continents joined at Panama three million years ago.
Before the interchange our continent had members of the camel family; South America did not. The camelids walked south and thrived on their new continent in the wild as guanacos and vicuñas and domesticated as llamas and alpacas. In the meantime camels went extinct here in North America. So there are wild camels in Peru but we have none.
Other animals made the journey, too. Here are just a few of the northern species that became successful in South America: camelids, squirrels, cottontail rabbits, deer, wild horses, peccaries, otters, raccoons, wolves, cougars, American sparrows (Emberizidae), trogons and condors. Click here for the complete list.
Initially the interchange was symmetrical with the same number of species going north and south but the result was lopsided. More northern species survived their move to South America than did southern species transplanted to the north. This was due in part to the difficult trek northward (deserts en route), our less hospitable climate (winter!) and the long isolation of South American fauna.
Opossums were one of the few success stories. We had no marsupials in North America until the Virginia opossum's ancestors made the journey and thrived on our continent. Many of their relatives still live in South America.
So what did we get when South American animals walked north? Not as much as you'd think: opossums, armadillos, porcupines, cougars, parrots, hummingbirds, tanagers, and tyrant flycatchers. Click here for the complete northbound list.
Cougars (Puma concolor) are on both lists because they were originally from North America and walked into South America. After they went extinct in North America the southern ones walked north to repopulate our continent.
We humans were part of the Great American Interchange, too. Our species' movement around the globe was made possible by continental land bridges.
What rodent is as big as a groundhog, looks like a squirrel, and has long legs like a small dog?
The agouti (pronounced "a GOO tee") lives in forests, nests in burrows, and eats fallen fruit and nuts. Eleven species in the genus Dasyprocta range from Mexico to South America and in the Caribbean. Four are endangered because of habitat loss and over hunting but the Central American agouti (Dasyprocta punctata), the species I saw in Costa Rica, seems to be doing fine.
Agoutis look like very large squirrels but their bony legs and extremely short hairless tails set them apart.
Like squirrels, they are diurnal but avoid humans because we hunt them. Where they feel safe, though, they're almost tame. At Las Cruces Biological Station they're protected so they stroll around the Wilson Botanical Garden and stop by the bird feeders every morning to glean the fruit knocked off the feeders.
This agouti was wary when I followed him at the garden to take his picture. I was amazed when he raised the greenish fur on his rump when I got too close. He lowered it when I stopped following him.
Despite their physical resemblance, agoutis aren't even related to squirrels. Their nearest relatives are guinea pigs.
(top two photos from Wikimedia Commons; click on the images to see the originals. Last photo by Kate St. John)
Okapis are forest dwelling mammals who eat plants and spend most of the time alone except when breeding. They reproduce slowly as the female is pregnant more than a year (440-450 days) before giving birth to a single foal. Unlike giraffes, only male okapi's have horns.
To save the okapi, John Lukas founded the Okapi Conservation Project in 1987 to buy land, set up conservation zones and work with local people to protect the okapi and improve the lives of those who live near it.
The project not only reduces human pressure on okapi habitat but relationships within the community save lives. In the blog post below John Lukas described how poachers with AK47s planned to kill a delegation of okapi conservationists last July. Locals passed through the ambush zone unharmed but knew their friends were in danger so they notified their chief who warned the delegation. Read how the ambush was foiled at the link below.