Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
The following photos were sent to me by a colleague, and were taken during a trip to Costa Rica during December, 2011- January, 2012. We’ll start with the crocodiles of Rio Grande de Tarcoles, which are an attraction for both Costa Rican and foreign tourists, who gather at the highway bridge to see the many large crocodiles gathered there. I was told on one of my visits there that there used to be some sort of slaughterhouse or rendering plant, and that the offal was dumped in the river, which initially attracted the crocodiles. People now feed them, although I think this is officially discouraged.
American Crocodile, Crocodylus acutus, Rio Grande de Tarcoles, Costa Rica, January 2012.American Crocodile, Crocodylus acutus, Rio Grande de Tarcoles, Costa Rica, January 2012.American Crocodile, Crocodylus acutus, Rio Grande de Tarcoles, Costa Rica, January 2012.
She also saw crocodiles on a trip to Tortuguero.
American Crocodile, Crocodylus acutus, on boat trip to Tortuguero, Costa Rica, January 2012.
Also at Tortuguero was this heron, a widespread species which is also found in the southeastern US, breeding at least as far north as New York.
Yellow-crowned Night Heron, Nyctanassa violacea, Tortuguero, Costa Rica, January 2012.
A visit to the area of Fortuna revealed a couple of species of mammals. This is a normally colored Mantled Howler Monkey,
Non-blonde Mantled Howler Monkey, Alouatta palliata, N of Fortuna, Costa Rica, January 2012.
while this one is “blonde”; I’ve never seen a howler of this color myself.
Blonde Mantled Howler Monkey, Alouatta palliata, N of Fortuna, Costa Rica, January 2012.
There were also bats.
Proboscis Bats, Rhynchonycteris naso, N of Fortuna, Costa Rica, January 2012.
And last but not least, because they are practically honorary cats, a squirrel from Volcan Poas.
Variegated Squirrel, Sciurus variegatoides, Volcan Poas, Costa Rica, December, 2011.
People are going nuts for an Ohio woodworker’s latest creation: A bar that caters to neighborhood squirrels.
Michael Dutko, a 35-year-old hobbyist, has been creating art and household items from wood for most of his life, and even chronicles it on his YouTube channel Duke Harmon Woodworking. But it’s his fun twist on a squirrel feeder that’s made him Internet famous.
“The Nutty Bar,” which is attached to his backyard fence in Hilliard, looks just like a real bar, and even has a range of nuts on tap.
Dutko said he built it to help his neighbor with her bird-watching hobby.
“The whole reason I even started to make this is because my neighbor bird watches with her daughter and told me all of the squirrels keep getting in her way,” Dutko told CNN. “I didn’t even tell her what I was going to do, I just built it and put it back there and when she saw it, she just started cracking up.”
Lucky squirrels who find their way to the bar get to choose from seven different nuts named after beers: Cashew Dunkel, Peanut Pilsner, Almond Ale, Walnut Stout, Sunflower Saison, Pecan Porter and Pistachio Pale Ale.
Dutko’s favorite part of the bar is its quirky bathroom sign: “Nuts” and “No Nuts.”
The project, which measures about 25 inches wide and 16 inches tall, took him eight hours to design and build.
After posting a video on YouTube showing the build process, Dutko said he was “overwhelmed” with comments and requests to purchase the bar. He immediately applied for a design patent and is now planning to launch a business to sell The Nutty Bar for about $175 – $200.
Many readers sent me this video made by engineer and inventor Mark Rober about his attempt to build a Rube-Goldberg-like bird feeder that would foil squirrels. (This is the ultimate pandemic project.) Thanks to all who sent this; it’s truly awesome (as the kids say), and “viral”, with over 14 million views in four days! (This may reflect people looking for cute videos while they’re quarantined.)
It’s a truly impressive project, but what impressed me even more was both the agility and the cleverness of the hungry rodents. If you’re one of the rare people who haven’t seen this, do watch. It’s a lot of fun.
You may remember Rober as the guy who devised a glitter/stink bomb package to punish those who steal boxes off people’s porches.
Because of a paucity of readers’ wildlife photos (I do have some, so if you sent them have patience), I’m deferring posting those till tomorrow, replacing them with a SQUIRREL CENSUS post by Greg:
by Greg Mayer
We’ve long been fans of squirrels here at WEIT, and so I was quite pleased to come across the following item in the New York Times, a combination of text, audio, video, and stills, on a census of the gray squirrels (Sciurus carolinensis) in Central Park. (Be sure to have the sound on for the squirrel vocalizations.)
And it’s not just because it’s squirrels– it’s the location, too. Research takes me every year or two to the American Museum of Natural History, which is located on Central Park West between 77th and 81st Streets, and I often walk across to Central Park to have lunch, where I enjoy the wildlife, including the squirrels. Mike Klemens of the American Museum did a herpetological inventory of Central Park, which I’ve remarked upon here at WEIT (the only herps I’ve ever seen are turtles in Turtle Pond), so I’m glad to see the squirrels get their due.
The Times also had two earlier articles about the start of the census, here
and here:
Going through the multimedia piece on the results of the inventory, I noticed this photo. . .
. . . of a melanistic squirrel in the Park. This is interesting for two reasons. First, I didn’t know there were black squirrels in Central Park—I’ve never seen one. (In New York City, “black squirrels” are a color form of the gray squirrel; in other places, the “black squirrels” may be fox squirrels, Sciurus niger.) Second, it shows that the black squirrels are not all blacks (sorry, New Zealand!), but usually have some reddish color in them. In the one above, the belly is quite extensively reddish; in black squirrels I’ve gotten close enough to see, there’s usually some red color on the back, although their appearance depends on the lighting; and from a distance they may appear all black.
I was hoping to look at the report of the squirrel census to see the prevalence and distribution of the black squirrels (as well as to find other fun squirrel facts), but was disappointed to find that the report will cost you $75! But, a single ring chart was visible on the census website—in a copy of the report opened to show what you would be paying for—and this chart shows that there were 140 black squirrels out of 3938 squirrels whose color was recorded: a frequency of 3.56%. (There’s also mention of a more common “cinnamon” morph, but I’m not convinced that’s a distinct morph.)
The Times piece also provided some bits of data. From the following figure, I was able to determine that of 2969 squirrels with a known color depicted, 103 were black, for 3.47%. (The “white” squirrels in the figure, 54 of them, are actually blanks—squirrels with no color data recorded. The pie chart had 74 such missing-data squirrels.)
I’m not sure why there are 3023 squirrels total in the Times‘ figure, but 4012 in the ring chart, but the two estimates of the prevalence of the black phase, 3.56 and 3.47%, are very close. It’s no wonder then, that the handful of squirrels I would see during my Central park rambles would not include any black ones.
In a nice “squirrel map” of all the sightings in Central Park in the Times piece, there are about 3 or 4 black squirrels recorded in the part of the park between the American Museum and the Turtle Pond, so they do occur there, but, again, at low frequency, so no surprise I haven’t seen them.
Today we have several photos of a rodential nature, and from two readers, whose comments are indented. As lagniappe, there’s a crustacean and a bird.
The first batch comes from Gary Womble:
Only whole grains for this little guy:
I would not want to get between him/her and those nuggets:
And finally, the kill!
A crustacean from Gary:
This little guy at Curry Hammock State Park in the Florida Keys takes its home everywhere it goes.
Another squirrel from Joe Dickinson (photo sent May 8):
Here is a squirrel photo with a moral: don’t leave food unattended in your campsite. It was taken this morning at New Brighton State Beach near Santa Cruz, CA . It is a neighboring campsite, not ours. The subject is on top of a cabinet inside of which is meant to be secure food storage. Clearly, the top doesn’t work so well.
From reader Tom Carrolan, sent March 21, who saw an American woodcock (Scolopax minor):
This morning, Blue Tusk owner Tim Yorton flagged me down coming out of Starbucks to show me a bird that had his staff in a tizzy… naturally.
I then did my “Woodcock Walk” for Tim, his bartender and bar-backs, cleaning crew, and kitchen staff. . . I’ve done dozens such programs on this subject over the years, but this was the first where glassware, brooms, and white chef’s coats were involved. I peented, described the bird’s display flight as a large falling maple seed, tossed in some nocturnal migration… well ya had to be there.
A trip to San Diego last month gave me the opportunity to check out the squirrel situation there. The native vegetation is coastal sage scrub and chapparal, with oaks and pines in higher and wetter areas, and desert to the south and west—very different from the deciduous woodlands of eastern North America which so many squirrels call home. The vegetation of San Diego has been greatly modified by man, however, with introduced species now dominating the cityscape– Eucalyptus (from Australia) and exotic palms (from everywhere) are omnipresent.
On the second day of our visit, we hit squirrel pay dirt in Balboa Park, a large urban park with little or nothing of its natural vegetation remaining. Appropriately enough, the squirrel was an introduced species, the fox squirrel, Sciurus niger. They were first recorded in San Diego in 1929.
Fox squirrels (Sciurus niger), Balboa Park, San Diego, California, 16 January 2019.
This pair was just outside the park’s visitors center. In the picture below, you can see the underside of the tail clearly. In Wisconsin, the shadings of the tail are the most reliable way to tell gray squirrels (Sciurus carolinensis) from fox squirrels– gray squirrels have white-tipped tail hairs, giving a ‘halo’ effect. Fox squirrels are very variable geographically, however, and this character may not work in all places, and I’m not sure where the San Diegan fox squirrels came from. (In a post here at WEIT a few years ago, I identified some squirrels from Texas as gray squirrels, but, given fox squirrels’ variability, I am now unsure of their identification.)
Fox squirrels (Sciurus niger), Balboa Park, San Diego, California, 16 January 2019.
A third fox squirrel, also outside the visitors center, sat in a classic squirrel pose.
Fox squirrel (Sciurus niger), Balboa Park, San Diego, California, 16 January 2019.
On another visit to Balboa Park a couple of days later, I was able to get up close and personal with this guy, and needed to use flash, hence the red-eye.
Fox squirrel (Sciurus niger), Balboa Park, San Diego, California, 18 January 2019.
The eastern gray squirrel (Sciurus carolinensis) was also introduced to Balboa Park, in 1924, but has apparently disappeared. During an 8-day stay I saw fox squirrels only in Balboa Park, not in other parts of the city. The native western gray squirrel, Sciurus griseus, is found only in the mountains in San Diego County.
Cities in the eastern half of the United States often have tree squirrels as a prominent element of their urban fauna. In much of the northeastern quadrant of the country, the “city squirrel” is the eastern gray squirrel, Sciurus carolinensis. From personal observation, this species is the city squirrel of Boston, New York, Washington, DC, Chicago, Milwaukee, and Madison, WI. As you head to the south and west, however, another species of tree squirrel, the somewhat larger fox squirrel, Sciurus niger, becomes a possibility. It is the city squirrel of Springfield, IL, and, quite exceptional for being so far to the north and east, Ann Arbor, MI. (On one of my first visits to that city, I remarked to someone that the city had the biggest gray squirrels I’d ever seen, and they replied, yeah, that’s because they were fox squirrels!) Both of these eastern species have been widely introduced elsewhere, the gray squirrel even overseas, including Great Britain and Ireland.
To see native squirrels, we had to go to San Ysidro, the southernmost part of the city of San Diego, on the Mexican border. As we walked to the border crossing there, we saw, on the slope to the east of the pedestrian approach, a modest colony of California ground squirrels, Spermophilus beecheyi. The white patch on the shoulder, extending somewhat in a line on the flank, is diagnostic; and in the out-of-focus individual in the background you can, paradoxically, see more clearly the dark area from the head onto the nape that separates the two shoulder patches. Note that someone seems to have thrown them a peanut (chewed on shell at left).
California ground squirrels (Spermophilus beecheyi), San Ysidro, California, 17 January 2019.
Ground squirrel tails tend to be less bushy than tree squirrel tails, but this species’ tail is fairly bushy. From the angle in the picture below, the squirrel even looks a fair amount like an eastern tree squirrel, since you can’t see its shoulder and nape.
California ground squirrel (Spermophilus beecheyi), San Ysidro, California, 17 January 2019.
In the next picture, we see a broader view of the colony, with scant, scrubby vegetation, including cactus; there were some scelrophyllous shrubs, as well. Bonus question: How many squirrels can you spot?
California ground squirrels (Spermophilus beecheyi), San Ysidro, California, 17 January 2019.
The ground squirrels also occurred just over the border in Tijuana.
California ground squirrel (Spermophilus beecheyi), Tijuana, B.C.N., Mexico, 17 January 2019, with Rock Doves (Columba livia).
There are many species of ground squirrels in western North America, but none in the east. (The easternmost is the thirteen-lined ground squirrel, which reaches the Midwest.) Many of these ground squirrels have more geographically or habitat restricted distributions. The white-tailed antelope squirrel, Ammospermophilus leucurus, is a desert species, which in San Diego County is found only in the eastern part of the county. The one below is in an exhibit hall, Coast to Cactus, at the San Diego Natural History Museum, devoted to the various biotic communities of southern California. It is a model, not an actual specimen.
White-tailed antelope squirrel (Ammospermophilus leucurus), model, at San Diego Natural History Museum.
And, to enlarge this account to include all of my encounters with incisor-enhanced critters in San Diego, here’s a Desert cottontail, (Sylvilagus audubonii), also in Balboa Park. Despite the common name, this is a common rabbit in a broad range of habitats, including urban-suburban ones, in San Diego.
Desert cottontail (Sylvilagus audubonii), Balboa Park, San Diego, California, 16 January 2019.
The San Diego Natural History Museum has been a leader in providing online access to its publications, collections, and exhibits, and for mammals there are a number of resources, and I’d point in particular to the various guides listed here, their checklist of the mammals of San Diego, and Suzanne Bond’s annotated list. They have recently published a truly excellent atlas of the mammal of San Diego, which I was able to consult while in San Diego, but not while writing this post, so if you’re interested in the exact details of the introductions and distributions of the species mentioned, you should consult the Atlas.
Bond, S.I. 1977 An annotated list of the mammals of San Diego County, California. Transactions of the San Diego Society of Natural History 18(14):229-248. pdf
Reid, F.A. 2006. A Field Guide to Mammals of North America. 4th ed. Houghton Mifflin, Boston. (The Peterson series mammal guide, and an excellent one; by browsing it, you can get a good overview of mammal distributions in the U.S. and Canada.)
Tremor, S., D. Stokes, W. Spencer, J. Diffendorfer, H. Thomas, S. Chivers, and P. Unitt. 2017. San Diego County Mammal Atlas. San Diego Natural History Museum, San Diego. Museum Store
Pulling into the parking lot behind my office this morning, an eastern gray squirrel (Sciurus carolinensis) sat in the middle of the road, blocking my way. This is an unusually bold posture for a squirrel– they are usually darting across roadways and parking lots: perhaps it knew it was Sunday, and wasn’t expecting any traffic? (This parking lot is not much used on weekends.) After a brief defiance, it relented and dashed off, which is when I saw the object of its mid-road attention– a treat:
It’s chocolate covered, looks like it might be peanut butter inside, and about 4 inches in diameter. The “chewed” side seemed more definitely chewed, with tooth marks, when viewed in person, than it does in this photo. I went out about 2 hours later, and the treat was gone. Presumably, the squirrel came back and absconded with it into the woods, which is a better place for squirrels to sit and eat.
I’m not sure if chocolate is good for squirrels. Chocolate is full of alkaloids, and unhealthy for some animals. I do, however, vaguely recall that squirrels in Costa Rica will eat cacao pods off trees, and this abstract seems to confirm that recollection. The tropical squirrels are in the same genus, but a different species, than the eastern gray.
Reader Lee Eberly from Iowa City sent a video of a most enterprising squirrel. His notes:
Gotta love ’em! Had not anticipated that when I installed the handrail. Sorry about the quality. Shot with iphone through plastic and window.
The video, posted on Susan Eberly’s YouTube feed, came with this description:
Did you know that squirrels will try over and over to reach your bird feeders? Not just one, not just tens of tries, but hundreds. And, like our favorite gray marauder, eventually they succeed. PS – Yes, “squirrelly” does have two rrs, and two lls (I looked it up).
Yep, there’s a whole one-hour PBS show on sciurids, “A Squirrel’s Guide to Success” (including chipmunks and other relatives) on PBS tonight. Go here to see when it’s playing in your area. It’s also available here after it airs.
To whet your appetite, here’s an excerpt demonstrating squirrel intelligence:
