Category Archives: amphibians

Late-morning hawk-watching – Part 1

Posted on by
3

North Carolina is known among birders as a destination for “hawk watches,” i.e., gatherings of people to see groups of hawks that are migrating south (for winter) or north (for summer). The Blue Ridge and Smoky mountains offer wind currents that birds can use to speed their journeys and many raptor fans travel to Grandfather Mountain’s Linville Peak to see the spectacle in autumn. Some also go to the hawk watch at Pilot Mountain State Park. The birds on view at the two sites include bald and golden eagles, peregrine falcons, kestrels, merlins, broad-winged hawks, Northern harriers, sharp-shinned and red-tailed hawks (Buteo jamaicensis) like the one below.

red-tailed hawk P9199890 © Maria de Bruyn res

As October progresses and migration is winding down, however, we continue to see resident raptors roaming in our area.

The red-shouldered hawks (Buteo lineatus) are looking for easy meals. Their favored foods, in addition to smaller birds and mammals, include amphibians. My yard contains a couple small ponds, which have become favored habitats for local bullfrogs and green frogs (Lithobates clamitans).

green frogs IMG_0021© Maria de Bruyn res

This year, the green frogs predominated; the largest ones especially drew my attention with their loud croaking. In between vocalizations, they looked like they were wrestling. Together they contributed to a bounty of frog eggs.

frog eggs IMG_0040© Maria de Bruyn res

red-shouldered hawk P6271585© Maria de Bruyn res

Their amorous calling also attracted one of the neighborhood red-shouldered hawks, whom I spotted sitting on a tree branch overhanging the smaller pond. S/he was patient in watching and a couple days later I noticed a lack of croaking and then found a hawk feather in the water.

belted kingfisher PA147080© Maria de BruynSome weeks later, I saw a belted kingfisher (Megaceryle alcyon) fly by quickly with a frog dangling from its beak at a city park, but the bird was too far away for a good photo. I had had better photographic luck on another morning when I happened upon a red-shouldered hawk pursuing frogs at nature reserve pond.

At first, I didn’t realize what the bird was doing. I saw the raptor intently peering down at the muddy pond’s edge and walking back and forth along the water.

red-shouldered hawk P8317401© Maria de Bruyn

red-shouldered hawk P8317412© Maria de Bruyn res

red-shouldered hawk P8317413 © Maria de Bruyn res

Then, suddenly, I saw the hawk plunging its claws into the ground, apparently trying to dig something up.

red-shouldered hawk P8317244© Maria de Bruyn res

It used its wings for balance as it clawed at the wet sand.

red-shouldered hawk P8317253© Maria de Bruyn res

red-shouldered hawk P8317252© Maria de Bruyn res

I felt sorry for the frogs that were caught. Their final life moments must have been spent in terror and pain as they were dismembered.

red-shouldered hawk P8317470© Maria de Bruyn res

red-shouldered hawk P8317604 © Maria de Bruyn

It seems to me that the great blue heron’s propensity to swallow its food whole must ultimately be a quicker death for the prey.

red-shouldered hawk P8317589© Maria de Bruyn res

red-shouldered hawk P8317535 res

The hawks must also eat, however, and this is the poor frogs’ fate in many cases.

red-shouldered hawk P8317506© Maria de Bruyn res

And I must admit that it was interesting – if also rather uncomfortable – for me to see how the hawk was hunting.

red-shouldered hawk P8317511 © Maria de Bruyn res

Next up – another local raptor keeps me watching in fascination.

When it’s time to eat your own skin

Posted on by
Reply

Several years ago, I bought a couple hard polyethylene pond liners and dug two large holes in my clay and rock-filled back yard. I wanted to have a pond area and figured that two big tubs would be easier to manage and clean than maintaining an in-ground pond. So far, that has been the case except for the fact that I couldn’t keep any fish – a great blue heron managed to eat all the fish I had over the course of about 2-3 years.

That doesn’t mean my pond is not populated, however. Indeed, all the water sources in my yard have residents. Some are unwanted – for example, the mosquito larvae that I admittedly kill with mosquito dunk. The Cope’s gray tree frogs (Hyla chrysoscelis) have a preference for my rain barrels. Somehow they manage to crawl inside even when a lid is on and they deposit hundreds of eggs per season.

   

Fortunately, not all of the frog eggs hatch or my yard would be overrun and the sound in the evenings would be overwhelming. Even the half-dozen or so current adults manage to produce quite a loud concert series – I’m surprised neighbors haven’t asked me to do something to tamp down the sound!

I used to have bullfrogs in my container ponds but haven’t seen them this year. Instead, my neighbors have been lovely green frogs (Rana clamitans). One grew to a very large size and he was joined by two others of a bit smaller stature.

They aren’t very noisy, mostly croaking in the late afternoon. It must have been that sound that attracted another neighborhood resident whom I spotted one day sitting on a nest box next to the pond. The red-shouldered hawks (Buteo lineatus) have spent time watching the pond before when in the mood for frog legs; this was a young hawk who had obviously been in the pond as evidenced by his wet plumage.

The pond was quiet for a few days and I thought the hawk must have had a good meal. And then, slowly, the frogs began to emerge again. There are three that sit on the rocks surrounding the larger pond although one is a bit smaller. This makes me think the hawk might have gotten one but that a juvenile frog was now accompanying the larger pair.

   

When my pond “greenies” croak, they don’t seem to get very large inflated vocal sacs. At the NC Botanical Garden, fellow photographer Mary showed me a green frog that she had been photographing and he croaked a couple times. It went too fast to get a good shot so I offered to make him “talk” by croaking at him. My pathetic attempt at imitating him really was quite pitiful, but amazingly did evoke a response. His vocal sac didn’t get really large either though.

One day, I spotted one of the yard frogs sitting on a rock, opening and closing its mouth without making a sound.

 

When I looked more closely, it seemed to have some membrane hanging on its side.

Then I saw that it was partly in the frog’s mouth and the amphibian was tugging away at it. I wondered if he was sick.

It turns out that he was perfectly healthy and staying that way by eating his own skin! These amphibians regularly shed their skin because it would otherwise harden and make it difficult for them to absorb oxygen while underwater, where they spend a considerable amount of time. So periodically, they scrunch themselves together and then stretch to break the skin so that it can be pulled off, leaving supple skin behind to better enable the “breathing” method called cutaneous gas exchange.

But why do the frogs then eat their skin? It actually has many nutrients, including calcium and proteins. I have no idea if the skin has any taste and whether they enjoy ingesting it. It seemed to be a bit of a laborious process when I watched this frog go through the process. Added to that is the fact that they actually use their eyeballs to push food down their throats and you discover that our froggy friends have quite a unique digestive process!

 

Outside my yard, I’ve not seen too many frogs this year. There was a lovely little Northern cricket frog (Acris crepitans) out and about on one of my walks.

More recently, I’ve been seeing Fowler’s toads (Anaxyrus fowleri) in the woods and parks.

 

     

At the NC Botanical Garden, I had the chance to see some rather large tadpoles sharing a pond with smaller ones.

It was interesting to see that the tadpoles first develop their hind legs and then their front legs before eventually losing their tails.

Finally, one more type of interesting creature I’ve been observing lately on walks are land snails. They don’t really belong in a blog that is about amphibians but it’s unlikely I’ll be writing one about mollusks any time soon. So, I’ll leave you here with a few photos of what I thought were some snails with beautifully spiraled shells. Have a good day or evening!

 

 

 

Finding joy in troubled times

Posted on by
12

While working on photos for other blogs, it occurred to me that it might be more productive right now to focus on what we, everywhere, are facing with the current pandemic. It’s my hope that as many of us as possible will survive, thrive and overcome the distress we are facing. As we hunker down, like this beautiful mourning dove (Zenaida macroura), we can intensify our nature observations – or begin paying more attention to the wildlife around us when we do go for walks.

 

Practicing social quarantine and distancing is essential –- even if we live somewhere where authorities are not yet requiring this. Keeping away physically from those outside our households can protect them as well as ourselves. In most places, social distancing rules still allow us to get outside for walks in the fresh air and nature. I have never seen so many people, including families with children, in the local nature reserves and that is a welcome sight. Hopefully, a side effect of this will be much more social support and advocacy for environmental conservation and expansion of natural areas, parks and reserves now and in the future -– that would be an unexpected positive outcome to the measures we are taking to get through these troubled times! (Yellow trout lily above, Erythronium americanum).

For people who haven’t had the pleasure of getting out much on walks, I wanted to share something about how to possibly enjoy nature even more. From my perspective, a key element is learning to practice patience and to stop, wait, watch and explore frequently. Here are some examples of what you might find. (Common Blue Violet, Viola sororia)

Looking down at the ground can be a fruitful exercise, especially in spring. Fresh new blooms are emerging and can delight us with their beauty (like the Eastern spring beauties, Claytonia virginica).

Bloodroot (Sanguinaria canadensis) – the leaves look like jigsaw puzzle pieces

Rue anemone (Thalictrum thalictroides)                  Tiny bluet (Houstonia pusilla)

Common chickweed (Stellaria media)

   

Little sweet Betsy (Trillium cuneatum)

   

Ground ivy – also known as creeping Charlie (Glechoma hederacea)

Henbit (Lamium amplexicaule) and purple deadnettle (Lamium purpureum)

If you are out with kids, you can pay more attention to the plants –- take photos of them (most reserves and parks don’t want people to dig up and pick flowers) and then look them up at home and learn about them. Or make a game out of fallen leaves –- find three with very different shapes and identify the trees.

If you look closely at the flowers, you might glimpse small bugs flitting around the blooms. If you have a camera or phone camera, try to get a photo. When you enlarge it, you might find that you have actually seen a beautiful fly, bee or other insect whose shape and colors you couldn’t see with the naked eye. If you want to identify it, post the photo to the site BugGuide.net, where entomologists can perhaps tell you what species you saw.

Parasitic fly (Goninii, above)

 

 

Greater bee fly (Bombylius major)

Various species of syrphid flies are shown below; they are often mistaken for small bees. The first photos are all of the species Toxomerus geminatus.

 

Male                                                               Female

And below the male and female together.

 

A species of syrphid fly with a striped abdomen (Syrphus torvus) is characterized by “hairy” eyes (more so in males, like this one). Click to enlarge and see the hairs.

A larger species, Brachypalpus oarus, is not so colorful.

Even if you can’t get outside much, you might see an interesting insect around your house. For example, this male brown-tipped conehead katydid (Neoconocephalus triops) appeared on my porch when I was sweeping.

Butterflies are really starting to fly around now. The bluish spring azures (Celastrina ladon) are abundant right now.

I’ve been seeing falcate orangetips (Anthocharis midea), too.

Damselflies are also starting to appear; we tend to see them earlier than the dragonflies, who spread their wings horizontally when they alight on vegetation. This fragile forktail damselfly (Ischnura posita) was getting covered in yellow pine pollen –- much of North Carolina’s Piedmont region is bedecked in yellow dust during the spring weeks when the pine trees emit clouds of pollen.

 

Looking in the water can be productive, too. One day, I spent some time scanning the edge of a pond where the water was shallow enough to see the bottom. As I watched little fish darting to and fro, I suddenly noticed something larger moving about quickly. I looked more intently and discovered Eastern newts (also called red-spotted newts, Notophthalmus viridescens) down there – the first time I had seen these amphibians!!

When you see an Eastern gray squirrel (Sciurus carolinensis) scurrying across the leaves in the forest or even alongside a road, stop and watch a bit. I did the other day and saw the mammal locate a winter stash and dig up some food it had stored. This article describes their storage process and reveals that they can probably remember where up to 95% of their stashes are hidden!

Paying attention to fallen logs can reveal beauty, too. This tree that fell across a creek ended up providing a growing place for common blue violets (Viola sororia).

As I walked by some other fallen trees, a common five-lined skink (Plestiodon fasciatus) popped briefly into view, gave me a pensive look and then disappeared into the leaf and twig litter.

Looking up at the trees, you might be lucky to see a wasp nest. The paper wasps (Polistes) make compartmentalized nests, with a place for each individual egg.

Or you may see a large bald-faced hornet’s nest (Dolichovespula maculata).

               

If you take the time to watch birds, you may see them engaged in looking for food (like insects, nuts, berries and seeds).

Tufted titmouse (Baeolophus bicolor)         Brown-headed nuthatch (Sitta pusilla)

Carolina chickadee (Poecile carolinensis) White-throated sparrow (Zonotrichia albicollis)

Blue jay (Cyanocitta cristata)                          Cedar waxwing (Bombycilla cedrorum)

 

Black & white warbler (Mniotilta varia)    Field sparrow (Spizella pusilla)

On one of my latest walks, I heard rapid knocking and was able to watch a yellow-bellied sapsucker (Sphyrapicus varius) engaged in beginning a new series of sap holes, which provide sweet drinking spots for themselves and other birds.

If you’re able to look at trees, bushes or nest boxes during walks or from your windows, you might catch birds collecting materials for their nests. Just the other day, I saw a Carolina chickadee gathering up some spider web to use in a nest.

If you find a nest, be sure to maintain a good distance, but then watch the parents bringing food to their nestlings after they hatch. If you’re lucky, you may even see the babies fledge! And if you are not near any trees, watch some birds at their nests through webcams online: https://www.allaboutbirds.org/cams/ – https://www.audubon.org/birdcams – https://birdwatchinghq.com/live-bird-cams/ –
https://birdcams.live/

If, at some point, we are “stuck” inside, we can follow this link to international wildlife days. If we find one to celebrate during our quarantine, we can spend some time learning about that animal and drawing or painting it. And we can do the same for other environmental days as well at this link.

To end, I’d like to share some resources with free online nature activities – for children and adults! Not all the sites require having a yard; even readers living in apartments could get out for a short walk and find something to see, investigate, etc.  Enjoy!!

 

 

 

 

Awesome amphibians in Costa Rica

Posted on by
4

During my two trips to Costa Rica (so far?), it was my good fortune to see different kinds of animals besides the birds which were the focus of the trips. There are a lot of interesting amphibians and reptiles to see; in this blog, we’ll see some of the amphibians that I managed to photograph. I was ultimately able to identify almost all of them except the one to the right; if anyone can tell me which frog this is, it would be appreciated!

 

One of the most famous frogs in the country is the little (0.75-1 inch) strawberry poison dart frog (Oophaga pumilio), also known as the blue jeans frog because many individuals have a bright red upper body accented by a bright blue lower half. It turns out that the species has an estimated 15-30 color variations – in 2000, totally blue individuals were seen at the La Selva Field Station.

The female lays 3-5 eggs on a leaf and the male then keeps the eggs hydrated with water he transports in his cloaca. After the eggs hatch and tadpoles emerge, the female frog transports them on her back and deposits each one separately in a small pool formed in the crevice or hole of a tree or a large bromeliad. There, the tadpoles consume only unfertilized eggs that their mother feeds, a practice called obligatory oophagy,

 

The feeding habits of the adults (certain ant and mite species) are what makes them poisonous when touched or eaten. Their skin is toxic and humans should wash their hands vigorously after touching them.

A very tiny frog that we saw last year was the common tink frog (also called dink frog; Diasporus diastema). I’m not absolutely certain that the two shown below are tink frogs but think they are. These tiny frogs change color, having grayish brown skin with spots or bars during the day and a pale tan or pink color at night, when it is most active.

 

 

A somewhat larger amphibian that we saw at the same pond as the tink was the hourglass tree frog (Dendropsophus ebraccatus). Part of the species name comes from the Latin term ebraccata, which means “without trousers”. Some people call this frog the “pantless frog” because they think the smooth yellow thighs that contrast with its highly patterned back make it look as if it is not wearing pants. These individuals had patterns on their thighs, however!

The attractive hourglass frogs were in an amorous mood when we spotted them. The female chooses her mate and he mounts her to deposit his sperm. She then will seek out a suitable place for her eggs, either in the water or a leaf overhanging water. When the arboreal eggs hatch, the tadpoles roll off the leaf into the water below.

These frogs are of interest to scientists because their skin contains bioactive peptides which have anti-fungal and anti-bacterial properties and might even have therapeutic properties useful in treating diabetes.

 

The pond had quite a few frogs in residence and several brilliant forest frogs (Lithobates warszewitschii)were among them. They are slender-looking frogs with pointy heads. Their sides are apparently always darker in color than their backs.

 

 

Their coloring seems to vary somewhat, being browner in some individuals and featuring more green highlights in others. They tend to have yellow spots on their legs.

They do not have vocal sacs or slits but do make trilling sounds.

 

 

We were lucky to catch a glimpse of a red-eyed tree frog (Agalychnis callidryas) at the pond. Although some lodges will ask you to avoid using a flashlight during night-time walks to see amphibians, it’s very difficult to spot them without some use of a light. That’s how we managed to spot the tree frog.

We came across the Canal Zone tree frog (Boana rufitela) taking a daytime nap, right out in the open on a large leaf next to a walking path. This frog is also known as the red-webbed or scarlet-webbed treefrog. It used to have the scientific name Hypsiboas rufitelus, which was changed for a reason I couldn’t determine.

The smoky jungle frog (Leptodactylus pentadactylus) is Costa Rica’s largest frog species; males grow to as much as 7.3 inches (18.5 cm). The adults are so big that they can eat small mammals (e.g., bats), small birds and lizards. They have some interesting characteristics. In contrast to the little blue jeans frogs, who only lay 5 or fewer eggs, female smoky jungle frogs lay about 1000 eggs at a time! They can secrete copious amounts of mucus, which makes them difficult to hold for predators; in addition, these secretions are toxic. They can even vaporize the toxin, causing people to sneeze and get swollen eyes.

What has further contributed to making them famous is the alarm call that they emit when captured; some liken it to a human person screaming. It doesn’t sound like that to me; rather, what I heard in a video sounds to me like a sound that a distressed cat might make.

That brings us to Costa Rica’s largest amphibian, the cane toad, also known as the marine toad. They are not only this Central American’s biggest amphibian, though; they are the largest toad in the world, growing as long as 9 inches long (22.86 cm) and weighing up to 3.5 lbs (1.59 kg).

This animal has also gotten a new scientific name; while it used to be called the Bufo marinus, it is now known as the Rhinella marina. Like some of the frogs, this toad has toxic skin and they are especially dangerous for dogs.

They were introduced to different countries to control pests as they have voracious appetites. Now they are considered an invasive species and pests themselves.

In 2018, I came across these toads in different places. There are a few living around a fountain in the hotel in San José where our tour groups stayed; they enjoy taking a shower under the running water.

To end today’s offering, I’ll show you the frog that really fascinated me most — the reticulated glass frog (Hyalinobatrachium valerioi). Our guide, Cope (who showed us the awesome spectacled owls and bats shown in previous blogs), led us to this awesome amphibian. It has a green and yellow back but its ventral (abdominal) skin is completely transparent! The frog’s heart is covered by white tissue and its liver and digestive tract are also white. Here you see the male frog on a leaf guarding eggs – he actually looks pretty much like the egg masses!

Isn’t nature endlessly interesting? Next blog: Costa Rican reptiles!