Craving crawdads in Carolina – a buffet for night herons

Many people in the USA, especially but not only in the South, grow up knowing what crawdads (Cambarus bartoni) are. This was not the case for me. My immigrant family pretty much stuck to the dietary customs of their own and their friends’ home countries (The Netherlands, Belgium, Germany). Like pumpkin pie, sweet potatoes and okra, crawdads were not on those menus and so it was only recently that I actually learned that these crustaceans are the same thing as crayfish, of which I had heard as a child.

This year was my time to learn more about these members of the arthropod family who are related to lobsters – it turned out they were thriving in a pond created through a man-made wetlands installed between a shopping mall and several apartment complexes. I learned about their presence when local birders alerted one another that the crawdads were attracting a family of yellow-crowned night herons (Nyctanassa violacea).

Hoping to spot the herons, I also visited the wetlands and first noted the crayfish remains scattered around near the pond. Shortly thereafter, I came across one crossing a path in another local nature park (photos above and below). It was interesting to see how the crawdad first stayed stock still as I neared and then stood tall on its legs as its tail propelled it backwards while it made a dash for the nearby pond.

The crawdad females lay hundreds of eggs; scientists do not yet know how long they incubate before birth but estimate it takes somewhat longer than a month before they hatch. In North Carolina, there are almost 50 species of these animals and several species are found only in this state.

The crayfish at the wetlands must have had a successful year because the place became a real buffet for various birds. Both adult and young night herons stayed near this pond for quite a long time before leaving to migrate to more southerly climes for the winter.

The adult herons were attractive with their boldly patterned heads.

 

 

   

They kept up their looks through regular preening.

 

 

Sometimes, they emerged from the pond weeds to perch on a snag while peering into the water on the lookout for a meal.

 

It was interesting to learn that while the adults have yellow legs most of the year, their legs can turn red or pink during breeding season.

 

 

In my experience, the younger herons were a bit less shy and didn’t fly off so quickly when I neared.

 

One in particular decided to take the sun in mid-August, adopting a pose that I more often see taken by great blue herons and which I’ve nicknamed the “flasher stance.”

     

The young birds, like their parents, stalked the pond vegetation on the lookout for crawdad snacks.

They also showed the herons’ taste for other food such as snails, earthworms and insects.

 

The night herons, for which most birders visited the wetlands, weren’t the only birds at the buffet, however. Red-shouldered hawks (Buteo lineatus) also showed a fondness for the crustaceans.

 

 

 

The herons weren’t always alert to their presence. One adult, for example, decide to fly to a low perch when chased away from a tall snag by a hawk. S/he settled in for a bit of preening but was then rudely chased off by the same hawk. (That hawk was later harassed by a group of crows, who chased it away in turn.)

Other herons who were interested in outdoor crayfish dining during the humans’ Covid epidemic, included the great blue herons (Ardea herodias).

 

 

Green herons (Butorides virescens) visited the pond regularly as well, eating small fish in addition to the other wetland delicacies.

 

 

 

 

 

 

Belted kingfishers (Megaceryle alcyon) were busy flying to and fro over the length of the pond, but I didn’t see them carry off any crayfish so they must have been focused on fish.

 

A great egret (Ardea alba) was a regular visitor, too, stalking different areas of the pond.

The adult night herons obviously thought it was interesting to watch the egret’s foraging technique.

Other regular visitors to the wetlands included a flock of Canada geese, American and fish crows, Northern mockingbirds and wandering glider dragonflies (Pantala flavescens).

 

There were so many animals feeding on the crawdads this summer that the female crayfish must have had a lot of success with their offspring reaching maturity. The last reported sighting of the yellow-crowned night herons at the wetland was 24 October, but I’m guessing that they will be leaving soon and the pond will not be so busy this autumn. The crayfish population had to have been reduced mightily over the summer season, so it will be interesting to see whether it rebounds and attracts crowds of birds — and birders — next year!

Helping monarch butterflies thrive

If you follow news about nature, you may have come across warnings that the monarch butterfly (Danaus plexippus) has been in rather dire straits for many years now.

 

These lovely orange and black butterflies live from 6 to 8 weeks when they are adults engaged in reproduction. Those who live in the Eastern USA participate in a multi-generational migration process between Canada and central Mexico. The last generation to emerge in late summer is able to delay its sexual maturity to undertake the last leg of the migratory journey (called reproductive diapause) and may live up to 8 months. Individual butterflies may travel as far as 1200-3000 miles to get to their warmer over-wintering grounds.

 

Since the 1980s, the Eastern US monarch population has declined by about 80%, mainly because the only food source for their caterpillars has been disappearing. Milkweeds used to grow abundantly in agricultural areas and along roadsides and ditches, but people have been eradicating the plants from fields and using herbicides and mowing to remove them along roads.

Climate change has also affected the butterflies’ breeding and migratory patterns so that reproduction has been reduced.

One way to help out the monarchs is to plant native (not exotic!) milkweeds in your own yard and any other natural spaces to which you have access. I’ve been doing it around my home and as a volunteer for the Mason Farm Biological Reserve. This year, I was lucky enough to be a beneficiary of a milkweed give-away organized by some local high-school students, so I had two types of the plants in my yard.

 

The ones that I had originally planted were common milkweed (Asclepias syriaca). These plants have large globular clusters of flowers that range in color from pinkish to purple. They do not have blooms their first year but that doesn’t stop the caterpillars from eating their leaves.

 

Butterfly weed (also known as butterfly milkweed; Asclepias tuberosa) is a bit more delicate and “exuberant” in appearance, with small clusters of orange, reddish and yellow flowers. These were the plants that I was gifted by the students and I was happy to see them grow quickly to exhibit their beautiful blooms.

According to Wikipedia, the butterfly milkweed is not a preferred plant for the monarch but this year the butterflies seemed much more attracted to it than to the common milkweed. After a few visits from some butterflies, I began seeing caterpillars and at one point counted 17 crawling up and down the various plants.

They were especially prevalent on the butterfly weed in my front yard and were munching the plants to bare stems very quickly.

 

       

To make sure they had enough food, I transferred some of them to the common milkweeds in my back yard – these were larger plants with much broader leaves and I thought this would ensure their healthy development. Frass (poop) was being left on the remaining leaves and the ground surrounding the plants.

 

It was rewarding to see three caterpillars make it to the chrysalis stage; the other caterpillars crawled away before I could see where they went, and I didn’t find them suspended from any plants. The first one had attached itself to a bare sapling and, unfortunately, the next day it had disappeared, leaving only the silken thread by which it had been suspended.

The caterpillars store milkweed glycosides in their bodies, making them toxic to many other animals. They still have many predators, however, including wasps, spiders, other insects, lizards, toads and mice. I resolved to save at least one chrysalid if I could.

I got to see the second chrysalis being formed (see the video, which is a little shaky at times). When the caterpillar is ready to undergo the pupation stage, it attaches itself to a plant stem by making a silk pad as an anchor (called a cremaster). Then it inserts the hooks at the end of its abdomen into the pad and hangs down. When the caterpillar forms a J shape, this signals the change to a chrysalis will soon be underway.

Starting from the head, the outer skin is shed, rolling up as the new covering develops. The shed skin may remain at the silk pad or fall off.

 

Slowly the stripes of the caterpillar disappear, and the chrysalis takes on a shiny even green hue, with some golden accent spots.

 

I kept that chrysalis, as well as a third one I saw the next morning, in my house and waited for them to darken. This signals the butterfly is almost through developing inside.

One morning I found the newly emerged monarch from the second chrysalis drying its wings. I took it outside so that it could fly free and then begin its trip to Mexico. (I also took the third one outside when it darkened but the twig holding it disappeared.)

 

You, too, could contribute to their propagation by planting some milkweed if you have an area for this. Autumn is the best time to plant seeds, but you can try it in the spring as well. Common milkweed typically doesn’t flower during its first year, but butterfly weed will give you flowers in its first season; the latter plants may be slow to emerge at first.

Both of these milkweed varieties are perennials so be sure to remember where you planted them. Common milkweed may spread out with time, while butterfly weed remains where you put it.

 

Other flowering plants will attract the adult monarchs, too, for nectaring, such as asters and lantana.

 

And then sit back next year and wait for the monarchs to arrive, happy in the knowledge that you have contributed to maintaining a favorable environment for their survival.

More ideas on how you can participate in the drive to save this iconic butterfly are detailed on a U.S. Fish & Wildlife Service website: https://www.fws.gov/savethemonarch/

 

What gets a birder really going? A rare bird!

People who are “into birding” are excited when they see a new bird for the first time. Many keep “life lists” – an account of each different species they have actually seen worldwide, in their country, in their state or province, or perhaps in their yard. When they see a new species, birders say they got a “lifer” – a first-time sighting in their life. Quite a few of these birders then decide to enjoy a reward – a lifer pie!

This past week, I was lucky enough to get a lifer, thanks to alerts circulated in the birding community. Doc Ellen Tinsley, the North Carolina Piedmont area’s main bald eagle researcher, also looks for other species when she goes out to see the eagles she knows. On 27 September, she was at the Jordan Lake Dam, where she often sees eagles whom she has come to recognize and know. Since it is the migration period for many birds that breed up North, she was also watching for warblers, a popular type of songbird because they are often beautifully colored.

She counted herself very lucky when she spotted a yellow striped bird that she had not seen before. After getting a confirmation of its scientific identification, she notified area birders that she had spotted a Kirtland’s warbler (Setophaga kirtlandii) and it was still foraging so people might be able to see it if they came to the Dam.

Until recently, the Kirtland’s warbler was considered an endangered species as it requires a very specific habitat in jack pine forest to breed. It depends on areas affected by fire; about 6 years after a conflagration, the space will be regenerated with small trees, shrubs and open areas that are favorable for its nests. When trees grow to about 10-16.5 feet high (3-5 m), the warblers leave to find a more suitable living area.

Compared to other birds, the Kirtland’s has the most restricted geographical breeding area of any bird in the continental United States. In the 1970s and 1980s, only about 167-200 males were counted in annual surveys. Conservationists in Michigan, Wisconsin and Ontario, Canada, collaborated on protecting the Kirtland’s environment and achieved success. This warbler has now been re-designated a threatened rather than endangered species. There are currently about 2,300 breeding pairs who migrate south to spend the winter in the Bahamas.

 

These birds’ diet comprises mainly insects and small fruit such as blueberries. Occasionally, they will catch an insect on the wing but more usually they glean pine needles and other vegetation for their meals. Spiders, moths and flies constitute part of their diet. Adults will also ingest pine sap.

 

 

These birds place their nests on the ground, underneath the small jack pines. The males will feed the females while they brood and both parents bring nutrition to the hatched offspring. In the past, brown-headed cowbirds often laid their eggs in Kirtland’s warbler nests and this contributed to their endangered status. Elimination of cowbirds from the environment for many years has now reduced the threat.

“As a condition for the warbler’s delisting, the USFWS, U.S. Forest Service, and the Michigan Department of Natural Resources signed a memorandum of understanding that the agencies will continue habitat management at sufficient levels to ensure a continued stable Kirtland’s Warbler population. Keith Kintigh, a forest conservation specialist with the Michigan DNR, says his agency will plant 1.8 million jack pine seedlings per year going forward to help maintain the 38,000 acres of suitable jack-pine habitat needed to keep the warbler population above the 1,000-breeding-pair threshold for recovered status.”
9 January 2020; https://www.allaboutbirds.org/news/kirtlands-warbler-delisted-after-47-years-of-conservation-work/

It’s likely that at least 100 people have traveled to Jordan Lake Dam to see this female bird. She was very popular because she didn’t particularly hide as some birds do. (She was sometimes a bit hidden by the pine needles, but that was because she was constantly moving about in the trees.)

She was foraging for insects along rocks bordering the dam area and in nearby trees, which gave the birders an opportunity to memorialize her visit with photos. Much of the time, she was seen in the company of a male bird of the Cape May species, who look similar (left).

The Kirtland warblers’ areas in Michigan and Wisconsin are closed to the public when they are breeding. They are rarely seen so there are guided tours in those two states to enable people to spot them.

 

Doc Ellen provided area birders with a wonderful opportunity to admire this rare bird! A much needed bright spot in a year that has been fraught with calamities.

 

Awesome amphibians in Costa Rica

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!

Marvelous mammals, part 1 – at the homestead

Judging from how many blogs I’ve written about birds, you might assume that I’m mainly a devotee of avian wildlife but that is certainly not the case. Without a doubt, I do love birds, but I really enjoy observing, learning about and photographing all kinds of other wildlife.  Fortunately, my own yard provides me with some opportunities for that as I have a number of regular mammalian visitors. Sometimes, their visits entail a bit of drama but often their presence is quite peaceful.

The Eastern chipmunks (Tamias striatus) like to visit the front porch to see if there’s something of interest among the potted plants or to take a drink from a water source.

These cute little rodents are more than willing to mingle with the ground-feeding birds looking for seed under the feeders. They scurry away as fast as their little legs will carry them when birds of prey appear – and they can certainly run quickly!

 

When it’s very cold, I sometimes offer them a small tray of seed just for themselves on the porch. They scarf down the goodies, filling their cheek pouches to what seems like almost bursting before dashing away to store the goodies for later consumption.

 

A pair of Eastern cottontail rabbits (Sylvilagus floridanus) lives in my yard and both mom and dad are very good about taking care of their young. I don’t see them much in the winter but expect they will be out and about again in the spring, doing their “leapfrogging” courtship ritual.

When it’s breeding season, I may see raccoons (Procyon lotor) in the daytime but lately they have been coming to the yard at night to pick up whatever seed is left on the ground from the daytime visitors. My wildlife cam caught a not-so-clear photo of this happening.

Another visitor who mostly comes at night is the opossum (Didelphis virginiana), one of my favorites given their propensity to eat lots and lots of ticks! Many people seem to think that they are ugly or scary, but I actually think they are kind of cute.

The largest mammalian visitors I see daily are the white-tailed deer (Odocoileus virginianus). I’ve loved them ever since I got to know a particular individual, whom I named Schatje (Dutch for “dear”). She approached me when she was a yearling and made friends with me, sitting next to me in the grass and thereafter bringing her newborn fawns to the yard right after their births. She unfortunately died in a car accident after some years, but through her I learned to really appreciate these mammals.

Some people dislike deer intensely because they eat their flowers and prized shrubs. But I’ve found that consistent application of a deer repellent on my plants keeps them off the vegetation that I want to preserve. Also, I let them eat bird seed and sometimes apple slices that I put out for the ground-feeding birds like white-throated sparrows, Eastern towhees, dark-sided juncos, American crows (the apple lovers) and brown thrashers.

So I’ve been watching the deer for many years now and a very odd occurrence happened over the past half year. At least four deer have appeared with broken hind legs or feet. When “Mama”, a doe with twins, showed up with a terrible break on her leg, I wondered if it happened when she jumped a fence. The bone was jutting out and it was obviously very painful. She hobbled on three legs.

What was amazing was the fact that her two-year-old son began caring for her. He already had a nice set of antlers and by rights should have left to join the stag group in the neighborhood, but he stayed with her and tended the wound, licking it, and also grooming her! I had not heard of a stag doing that before, so I named him Sweetie. He stayed with her for months!

Mama kept caring for her twins (a male and female). (The past couple years, she had only had male offspring so that cut down on the number of deer we might otherwise have had). And she tended her wound on her own as well.

Mama also had to withstand the advances of the dominant neighborhood stag, who was intent on mating with her. Sweetie tried to be there to fend off the interloper, but he had to give in and move off as he was no match for the big buck. Mama tried to get away, but he kept trying to mount her – unsuccessfully, since her back quarters would collapse as she could not bear any weight on the broken leg. She finally got away and ran, which must have been terribly painful for her.

 

Mama could not stand up for herself with the hurt leg so she began being bullied by another doe who showed up. That deer, who I called Bossy, was ill-tempered and a bit nasty; she even would chase her own son away from seed on the ground, even when her son also got a broken leg!

Then two adult males turned up with breaks – one had a broken foot. I wondered if someone was feeding them deer corn, which can be bad for their health and affect their hooves so that perhaps leg breaks would happen more easily. Or was someone taking potshots at them? It remains a mystery, but I’ve learned that the deer can overcome something like this although the healing takes months.

And then we come to my “nemesis” yard mammal, the Eastern gray squirrel (Sciurus carolinensis). As all bird-feeding people know, squirrels will do their utmost to eat all and any bird food that is put out — this has generated an industry devoted to producing squirrel baffles and “squirrel-proof” feeders. Even when I had smeared a bit of suet on a holly bush for the ruby-crowned kinglet who was sometimes crowded away from the feeder, a squirrel discovered the treat there and consumed what s/he could.

I’ve been fairly fortunate in having the baffles work until recently, when a couple squirrels used their little brains to figure out ways to get around them. It was my belief that I had put the feeder poles sufficiently far from the roof or large tree branches so that the squirrel couldn’t make the leap. One kept trying over and over and finally succeeded in lengthening his/her “long jump”!

I moved the poles further away. But two poles were about five feet apart and I then saw a squirrel use a strategy that really looked very clever to me. S/he would take a run at one pole, launch him/herself onto the pole at high velocity just under the baffle and then turn to vault from that height up and over the baffles on the neighboring pole! I really did admire the creature’s ingenuity and gained a new respect for their intelligence.

After moving the feeder poles further apart, I then noticed that a couple feeders on one pole were being emptied quickly. Looking out my window one day, I saw a squirrel perched atop the pole, enjoying seed after having managed to move the baffles down the pole. How was s/he doing that?

 

I set aside time to watch and discovered the squirrel’s secret.

 

The animal was hanging onto the raccoon baffle, biting it and jerking down at the same time. This eventually loosened the screws in the apparatus on which the baffle rested so that the baffle finally slid down the pole!

 

The screws have now been tightened and the next move is up to the squirrels. They are clever and tenacious. This was further brought home to me when a red-tailed hawk (Buteo jamaicensis) recently landed on a squirrel nest and did its best to extricate the mammal with its claws. The hawk eventually had to leave without its envisioned meal.

The yard mammals are certainly entertaining. If any of you readers have had interesting experiences with them, I’d love to hear about them in comments on this blog’s page! (Except for cats running free outside – goodbye from my two indoor cats, Ogi and Moasi!)