A bountiful year for seeing Castor canadensis

It has been my privilege to go on safaris in Africa and my outings in nature there resulted in sightings of multiple mammalian species each time. Where I live now, there are also a variety of mammals but I don’t see them often, other than squirrels, chipmunks, deer, opossums and raccoons. I was lucky to see chewed trees as evidence of American beavers’ (past) presence, but I was not seeing members of the Castor canadensis species. Some of the chewing patterns on the trees were interesting though.

I saw my first beaver lodge at Brumley Nature Preserve South in early 2016 and had the good fortune to get a quick glimpse of a beaver there. (Before that, I had seen them in zoos.) Then I began noticing beaver dams more often on walks, like the one below near the Haw River. So for my first long blog of 2019, I’d like to share with you how 2018 became my bountiful beaver year.

In the spring, a friend told me about a creek where beavers’ dams had resulted in marvelous wetlands along some nature trails. Their handiwork at Pokeberry Creek was appreciated by a considerable number of nearby residents, who were pleased with an increasing number of waterfowl and other birds at the wetlands, as well as otters.

 

They spoke about the benefits of beavers’ presence, such as the increased biodiversity, improved water quality and more opportunities for wildlife viewing, and celebrated their arrival. Some birding groups began leading walks there to view the numerous songbird and other avian species.

For me, the chance to see the beavers in action was wonderful. One day, I saw an adult chewing branches as part of its meal; it was quiet and didn’t seem disturbed to have me nearby watching.

On other occasions, I saw individuals bringing reeds back to a lodge, presumably to feed young ones left at home. (The offspring may stay with their parents up to two years.)

As beavers are mostly crepuscular, visiting at dusk offered a good chance to see them at work felling trees for their dams and lodges. It struck me that when I had observed them eating, they were very quiet. When they were working to cut trees down, however, I could hear them chewing very loudly.

Some people living near Pokeberry Creek brought chairs and drinks to watch the animals at work in the evenings and everyone present seemed to be learning a lot about them. Apparently, many people are interested in beavers – the ranger station at the Jordan Lake Dam has a taxidermied beaver and information about their lodges on display.

Nature’s aquatic engineers are certainly interesting mammals. North America’s largest rodents can swim underwater without coming up for a breath for some 15 minutes; this is because they slow their heart rate. Their transparent eyelids function as goggles so that they can see underwater.

They build dams to ensure that the ponds in which they construct lodges are deep enough so that the entrance remains under water. When the water is at least 2-3 feet, they will be safe from predators and the entrance to their home will stay ice-free in the winter. If they are in a spot where the water remains high enough all the time, they may forego building dams. At Pokeberry, the animals felt a need to build dams in two places. Research has shown that the noise made by water flowing away contributes to their decisions to shore up dams; they apparently cannot tolerate the sound of running water above a certain number of decibels.

The beavers’ environmental engineering irritated some members of the Home Owners Association (HOA) of a nearby community which is still under development. Some people complained that the water was encroaching onto properties (other property owners were ok with it). The rising waters also sometimes flooded a long walking bridge and a cul de sac. Numerous repairs were needed for the bridge and “opposing” parties emerged.

After the HOA announced a plan to have 35 beavers killed, a petition to save the mammals was begun. Within a few days, more than 3700 signatures had been gathered and the HOA undertook a consultation process with different agencies to explore other options. The Friends of Pokeberry Creek Beavers and Wetlands, in the meantime, put up small barriers so that the waters would not encroach so easily onto the cul-de-sac. They also installed a “beaver deceiver” (a pond leveling device, comprising large tubes inserted through a dam so that water would continue to flow through).

It appears that the beavers found the water flow too noisy, so each evening they would mud up the fencing around the deceiver intake so that no water could enter there. The humans would take away the mud; the beavers would put it back. The humans moved the pond leveling devices to deeper areas, but with heavy rainfall, the waters would rise very high.

Finally, in early autumn, the HOA had much of the wetlands drained. This was done to avoid killing the beavers by driving them further downstream to find another area where they could build dams to establish a new pond territory.

The beavers in a large pond that remains rather full have not moved; they are still felling trees, presumably to reinforce their lodge and to have some food supplies in stock for the winter. They also need to keep chewing as their teeth never stop growing. When they remove trees, they leave stumps of about 6-12 inches behind. I’ve seen some of these tree stumps, such as a tulip poplar, sprouting branches again. So the beavers’ tree clearing does not have the same effect as clear-cutting done by humans.

   

  

I thought that the drained wetlands at Pokeberry Creek might be the end of my beaver observation opportunities, but then I discovered that another wildlife and recreational park was facing challenges from beaver dams. Sandy Creek Park had had beavers some 5-6 years ago and at that time the mammals were removed (killed). The park manager wants to avoid that now if possible, but the dams need to be controlled since they are causing flooding onto paved pathways which help make the park accessible to persons living with disabilities.

A wildlife biologist visited the park to assess the potential success of a pond leveler there; because the pond in question is rather deep, they may have more success with a beaver deceiver. I’m guessing it will also depend on how the noise levels evolve with the new flow of water into the nearby creek. If they can install a silent outflow pipe, the intervention may be successful.

In November, I found that beavers were also busy at a third natural area that I visit often, the Brumley Nature Preserve North. The rodents are busy in two of three ponds there. The volunteer trail steward periodically breaches the dam at one pond so that the water can continue flowing downstream. When the pond water level remains high enough, the beavers seem to be more lax in repairing the dam.

  

At the other pond, the water level has stayed fairly consistent with all the rainfall our area has had in the past months and no beaver engineering seems to be happening there. As there is no obvious stream flowing into that pond, if we have a dry summer, the beavers may have to abandon that home as the pond could dry up as happened during a drought period last year. There was an interesting development at this pond, however. It involved one particular beaver who recently spent afternoons for a couple weeks swimming laps for hours.

I was quite surprised to see him (it could be female but somehow I thought of this individual as a male who was hoping to attract a mate), since beavers often prefer not to be out in the open during the day. He even emerged from the water from time to time, but always on the other side of the pond.

 

It didn’t matter whether the day was sunny or colder, gray and overcast. Sometimes, it seemed that he was taking a quick power nap.

  

The beaver would make small circles, large circles, go to the shore for a quick rest and then resume laps.

One day, I saw him swim toward the lodge and I was able to see inside above the underwater entrance. He didn’t stay there long though and soon came out again to exercise.

This beaver seemed to be quite relaxed, swimming around and around, except for when walkers came by with dogs. He definitely did not care for the canines; when they appeared, he often would begin slapping his large, flat tail on the water and then diving noisily under water before emerging again nearby.

These tail slap warnings and dives showed off his webbed hind paws.

It was interesting to hear how very loud the tail slaps can be. The beaver will also vocalize its distress.

At one point, some visitors to the reserve allowed their dog to jump into the pond and the canine swam close to the beaver lodge. (Dogs are supposed to be kept on leash but a number of pet owners ignore the sign stating this. When I mentioned that dogs running loose also disturb ground-feeding birds, the response was: “Too bad for the ground birds!”) That very much disturbed the beaver, who slapped his tail again and again.

After that incident, I only saw the beaver having afternoon lap sessions a couple more times. He seems to have given up the practice or is now restricting his swims to very quiet times. I can understand if the animal is trying to avoid stress and distress; that’s one reason I go out for nature walks, too. But I was glad he ventured out for a while so I could see him fairly close on several occasions.

Happy New Year to you all – hope your 2019 is happy, healthy and filled with nature’s beauty!

Growing up barred – Part 3: Strife and affection

In the nest, baby barred owls (Strix varia) are vulnerable to predators including hawks, weasels, raccoons and other owls. When they are out on their own and already able to fly, they eventually have less to fear. Their main predator becomes the one owl larger than they are in North Carolina, the great horned owl.

As pointed out in the previous blog, however, they can be fearsome predators to many other species of animals including songbirds, woodpeckers and other avian species. On a few occasions, I noticed the young owls at the Mason Farm Biological Reserve gazing about with expressions that seemed to express wonder and confusion.

It turned out that they were being dive-bombed by members of a very small bird species, the blue-gray gnatcatchers (Polioptila caerulea). The owlets seemed to have no interest in pursuing the gnatcatchers, but they were perching in areas where the small birds had had their nests so the little gnatcatchers did their best to drive the owls away.

  

One day, they succeeded. The owls flew to the other side of a path through a bog. One landed on a branch right over my head and looked down at me with what I imagined was an expression of “Hey, what did I do???”

The young owls were very affectionate with one another. They often perched next to or near one another.

 

They often sat close together, expressing what looked to me like affection.

 

 

When they were apart, they would vocalize. It would have been cool to be privy to the meaning of their communications.

 

The young birds seemed to enjoy nuzzling and grooming each other.

 

  

When I stopped seeing the young owls in their usual haunts, I figured the time had come for them to separate and seek out a mate and new territory. Mated owls usually establish nests about 400 yards away from other barred owls although some nests have been observed as close as 100 to 200 yards apart. The young owls may not have flown very far away but they did need to leave their parents’ area. I hope they made it and was happy to have had the opportunity to watch them mature. My next goal for owls – to see a species in the wild that I have not yet seen (e.g., great grey owl, screech owl, barn owl, etc.). I hope you, too, have the chance to see members of this avian group up close!

When those loving instincts leave you dangling

This was not a planned blog, but I recently observed something that simultaneously intrigued, amazed and astounded me, so I wanted to share it with those of you who may not have witnessed this either.

Like many gardens in my neighborhood, my yard has its fair share of leopard slugs (Limax maximus), but they don’t bother me as they do some other people who complain about them eating their vegetables. Until recently, I never thought about the slugs much and certainly didn’t wonder about their life cycle. Then my friend Mary posted a lovely photo of two intertwined leopard slugs mating and my interest and curiosity were piqued.

A few days later, a fellow nature lover, Ace, reported that he had a cool photo to show me – and there on his iPhone was a photo of mating leopard slugs. It turns out that their anatomy makes for a somewhat bizarre spectacle – at least to a human being if not a fellow slug. Now I really wanted to see this phenomenon, too, and I followed Ace’s recommendation, going out into my yard at night with a flashlight to see if I could find some amorous mollusks. Lo and behold – as I rounded the corner of my house, there were three pairs of large slugs getting ready to reproduce! They were leaving glistening slime trails on the brick wall as they slowly got into position.

The slime that the slugs exude has multiple purposes – they can leave a trail behind them as a signpost to the way home, they can numb the mouth of a potential predator with the mucus as a means of defense, and they can broadcast their interest in some reproductive behavior by emitting pheromones to attract a potential mate.

They don’t actually need to mate to reproduce – each slug is a hermaphrodite and can fertilize its own eggs with no need of outside assistance. Slugs have an organ called a spermoviduct (SO), which has two parts – one for the sperm (vas deferens, VD) and one for the ova (oviduct, OV), as seen as this drawing from the Wikipedia page.

Some slugs apparently like reproductive acrobatics, however, and seek out a partner. The mating begins with a pair of slugs following one another around and nudging and licking one another. (A couple photos look browner – I took those with a flash but most were taken with one hand holding a small camera and the other shining a flashlight near the slugs.)

 

They then begin to curl up together and suspend themselves from a long mucus rope, which is somewhat stronger than the slime that they usually exude. They form a kind of writhing ball as they intertwine their elongated bodies (see this video for an example).

Next comes the awesomely weird part – out of a gonopore on the right side of their heads (the elongated tentacles are for vision) come their translucent mating organs (penises)! This video, which is shown in a horizontal position, lets you see how this happens.

Wouldn’t this interesting anatomy and reproductive behavior make an interesting plotline for an SF novel about a genderless society?

 

      

Because the slugs are hanging upside down, gravity helps pull down their reproductive organs, which are pumped full of body fluids until they are as long as the slugs’ entire bodies! Their penises are everted (turned inside out) and the two mollusks intertwine these just like their bodies. They take a while to exchange spermatophores as the penises twirl, intertwine, elongate and pull back to look a bit like a chandelier.

  

When the creatures have been joined at the neck for some time, they begin to slowly withdraw their reproductive organs, which are now carrying genes from another parent.

              

After they separate, one of the pair usually consumes the mucus rope from which they dangled in love as it carries extra nutrients which they can use after their vigorous efforts.

          

 

 

Each slug may spend some time examining its gonopore (above) – and perhaps they are helping push back in the penis when they do this, too. After watching the process for two pairs of slugs, I decided to give the third pair some privacy during their mating tryst. On the wall beneath my screened porch, I discovered another slug with a mucus rope dangling from its tail – leaving me with a little mystery as to why this might have happened. A partner slug was not in evidence except for a much smaller slug – perhaps the big one tried to mate but the younger one was not ready. These mollusks with a life span of 2.5-3 years don’t become sexually mature until they are 2 years old.

    

I do know that at least three and perhaps six slugs will each be laying up to 200 eggs somewhere in the yard. And when I see them in the future, I will undoubtedly always be picturing them in my head doing their dangling dance with intertwined translucent blue tubes that will help promote their future generations. My discovery of their life cycle has also reinforced my support for scientist Hope Jahren’s (Lab Girl) observation: “…being able to derive happiness from discovery is a recipe for a beautiful life.”

Who wants to eat?

First, let me welcome those of you who have become new followers of my blog – nice to have you reading here and I hope you comment on what you like! I am way behind on my postings for the blog but will try to remedy that. There are photos almost ready for a series on bird courtship and child-rearing, as well as some other non-bird topics, but various issues have been keeping me from completing the texts. Now that I have had to take my preferred camera in for repairs, however, I have a bit more time to work on the blog and a recent brief trip to Topsail Island is providing some almost ready-made postings.

The south end of Topsail Island has been eroded greatly by the Atlantic storms, including effects from Hurricane Irma. Where normally the beach sloped up gently to beautiful dunes, these have now been sheared off vertically and the sea grasses and other vegetation before the dunes have been swept away.

 

 

That is of concern as the sea turtles nest there; hopefully, there will be sufficient places for their eggs next year. There were far fewer shells on the beach but at low tide the swath of empty sand was very wide.

 

Mixed groups of birds were resting there in between ocean fishing expeditions. There were a couple immature common terns (Sterna hirundo) who were begging for food incessantly, but the adults pretty much ignored them, preferring to preen or settle down for a rest.

Some of the begging was pretty vigorous, accompanied by feather ruffling and shaking but I didn’t see any parents go off for food.

The sandwich terns (Thalasseus sandvicensis) were also resting but individuals took off frequently for a fishing flight. These terns are easily identifiable by the yellow tips on their black bills and their Groucho Mark hair-dos, a boon for people like me who are challenged in recognizing which shorebird they have before them. Sometimes, you could imagine a conversation taking place between them.

Hi! I’m back from fishing!

Didn’t take long, did it?

See, I got a fish!

Wanna smell it?

Not to your liking, huh?

Walking in circles around me won’t make it any different

I think I’ll go feed a young one!

There were two immature sandwich terns who were very persistent in asking for a meal.

Come on, Ma, I’m hungry!

I am really really hungry!

Oh yum, lunch!

That’s right, put it right here!

Thank goodness you brought me something!

I’m STILL hungry!

Perhaps the adult sandwich terns were accommodating to their young as they have a lot of experience in raising them – the oldest one on record lived in North Carolina and reached the ripe old age (for a bird) of 24 years and 2 months! (However, the oldest common tern on record was 25 years, so perhaps the sandwich terns are just more caring?)

The birds were quite entertaining to watch and I have more photos to share from that trip. I will try to intersperse them between postings on avian child-rearing. Have a nice day!

An evening at Bolin Creek

After a day waiting for four bluebirds to fledge (next blog!) and a health-care appointment, I decided to forego some chores and instead to spend some time at a bridge over Bolin Creek, a waterway in the local Carolina North Forest which belongs to the University of North Carolina. My naturalist friend Mary discovered that this spot is a favorite bathing spot for birds in the late afternoon and evening. Since the weather forecasters predicted rain most afternoons this week, I decided to make a quick foray there while I had the chance. I knew that photographing the wildlife could be difficult as the sky was dull, overcast and we were expecting a downpour but I was up for the challenge. And once in a while a bit of brightness emerged from behind the clouds to give me some encouragement.

At first, it seemed very quiet – no bird song or buzzing insects; I thought perhaps everyone was hunkering down in anticipation of a coming rainstorm. But then the sky lightened a bit and a handsome robber fly (Promachus) alighted on a nearby leaf. I think this is a red-footed cannibal fly; these insects look like little old men to me.

 

 

A little while later, there were suddenly three avian visitors. The female Eastern towhee (Pipilo erythrophthalmus) was the first to take a bath.

     

 

The blue-gray gnatcatcher (Polioptila caerulea) didn’t go to the water but flitted overhead.

 

The first of two American redstarts (Setophaga ruticilla) also hopped from branch to branch but eventually ducked behind some rocks to bathe.

A pair of damselflies hung out on the stream rocks; the blue-tipped dancer’s (Argia tibialis) dark purple made it look almost black in the twilight.

 

 

Then a beautiful female hooded warbler (Setophaga citrina) came by for a bath. Her golden feathers shone in the dark foliage and against the stream rocks.

 

 

 

A pair of gray catbirds (Dumetella carolinensis) came together but only one entered the stream for a thorough drenching of its plumage.

 

 

 

   

The redstarts returned but stayed on the branches as the daylight began leaking away.

A few other birds were in the vicinity but didn’t come near: American crows, Northern cardinals, a common grackle and two yellow-billed cuckoos. My visit ended when the sky really darkened — I started down the path in an effort to reach my car before the rain began. A Southern leopard frog (Lithobates sphenocephalus) crossed in front of me and paused in the grass, enabling me to get a quick portrait. And then a nettle of beautiful violet color called out for a photo, too. I made it to the car just as the first raindrops fell. Quite an enjoyable impromptu photography session!