Aquatic mammals making my day! Part 2

0 beaver PA299293© Maria de Bruyn res

In 2019, I came across a few areas on walks where beavers were active and local residents were enjoying their presence. The animals weren’t shy and would come out in the mornings and evenings to eat and work on their lodges and dams, so I was able to observe them fairly often.

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In the intervening years, people have taken varied actions to deal with these mammals at the sites I visit, and my sightings have decreased. So, I was very pleased this past fall when I came across a beaver who had put aside his (or her) shyness and was coming out to swim often during daytime hours at one pond.

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One day, this amiable animal decided to have a prolonged grooming session and gave me some good looks at its anatomy. S/he had what is considered a typical beaver tail: large and flat. Later I learned that beaver tails differ from animal to animal, with tail shapes (short, long, narrow, broad) being determined by individual and family traits.

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Their large tails not only assist them in swimming and balancing on land — they also serve as a storage unit for fat that can be accessed during winter periods with less food available. Those tails can increase their body fat supply for cold weather by as much as 60%!

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The beaver has long digging claws on its front paws.

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Their hind feet have two specialized toes which were described by Vernon Bailey in 1923 after he had studied young beavers in his home. He called these inner toes the combing claw and the louse-catching claw. The innermost toe he termed a coarse combing tool and the second toe a fine-toothed comb.

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The second toe, which has a double toenail, is now called a preening toe or grooming claw.

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These toes are useful tools, as their comb-like action during grooming helps prevent the beavers’ soft fur from matting. (Unfortunately, the beaver only used his/her front paws while I watched; I’d like to see those back claws in action!)

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Beavers may spend almost 20% of their time on preening and grooming as this activity helps them remove burrs and parasites and aids in keeping their fur’s insulation and waterproof characteristics intact.

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An oil from abdominal glands is used to help waterproof their fur, too. Scents from these glands are further used to mark territory. And, oddly, castoreum (one of their castor gland secretions) smells and tastes like vanilla and has been used in human food preparation. Fortunately, it is difficult to obtain (the beaver must be anesthetized and “milked”) and scarcely used – about 292 lbs. (132 kg) yearly around the world.

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The beaver’s well-developed whiskers are useful in dark water and narrow burrows because they help the animal detect objects.

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Like birds and otters, beavers have a nictitating membrane to protect their eyes underwater. They can also keep water out of their ears and nostrils by closing anatomical valves.

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The beautiful beavers have been designated a keystone species because of their important role in creating environments suitable for other animals and plants. The habitats they create remove pollutants from ground and surface water. Their dams act as water filtration systems and help lessen compounds such as nitrogen and phosphorus so that we can obtain cleaner drinking water. In addition, some research has shown that the plants and algae in beaver ponds may help remove toxic metals from water, including lead, arsenic, copper, mercury, cadmium and selenium.

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There are ongoing efforts by some people in our area to get rid of beavers but fortunately an increasing number of advocates are looking for ways to coexist with beavers in urban and semi-urban areas. Researchers from local universities are aiding in the effort and hopefully this will lead to co-existence successes!

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And some closing words…. When I was a child, I loved a small statue of three monkeys that sat on a shelf in our home: “speak no evil, see no evil, hear no evil.” I liked the message and the fact that it was advised by an animal. Unfortunately, over the past decades, the statuette did not survive intact, but I’ve kept it nonetheless.

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Here below we have a new version, brought to you courtesy of my friendly beaver. 😊

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Speak no evil!

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See no evil!

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Hear no evil!

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And have a wonderful upcoming day, week, month and year!

Next up – back to birds of the woodpecker family!

Aquatic mammals making my day! Part 1

1 river otter P1154270© Maria de Bruyn res

While I love all wildlife, many of my blogs feature birds because my chances of seeing them are greater than seeing other animals. Mammals are a favorite of mine, however, and aquatic mammals are always a pleasure to see since spotting them is not always easy. That is certainly the case for the cute river otters (Lontra canadensis) like the one above.

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These river and pond residents are among the most elusive mammalian water residents for me.  At one pond that I visit regularly, they appear to have adopted an abandoned beaver lodge as their home. There, it is usually movement caught out of the corner of my eye that alerts me to their presence.

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Sometimes a view of the rump and tail is all I get as they barely lift their heads out of the water. It’s interesting to know, however, that their tail comprises up to 40% of their body length, helps speed them up to 8 mph (13 Km/h) in the water, and helps them dive up to 36 feet (11 m).

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5 otter PA309953© Maria de Bruyn resThe otters don’t always appreciate spectators. Sometimes, they emerge from the water briefly and give me a view shrouded by vegetation before they dive back down. That’s frustrating when you’re trying to get a nice photo, but at least I’ve never scared them enough for them to sound their alarm scream, which apparently can be heard up to 1.5 m/2.4 km away!

8 beaver lodge IMG_0294© Maria de Bruyn resThe other day at another pond, I was lucky enough to see a pair close to shore. They were foraging and when they finally disappeared, they appeared to have entered a beaver lodge located next to a walking path (seen here). The beavers may have abandoned this lodge as they have at least two others in this park.

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Researchers have not yet agreed on when otters enter their breeding season; it could be winter, late spring or summertime according to different studies. In any case, it seemed to me like this might be a mated pair.

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As they swam around, the couple would occasionally come together.

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They didn’t stop to frolic, however, even though otters are known for their playfulness. They did blow some bubbles and I’ve learned that they can close their nostrils during dives to keep water out of their noses. Seeing them was a real treat! And their presence should indicate good fortune for the Sandy Creek Park since river otters are considered an indicator species that signal good water quality.

11 river otter P1154272 © Maria de Bruyn

In September, I wrote about seeing muskrats (Ondatra zibethicus) and North American beavers at a third reserve. Since then, I’ve had the good fortune to see both species there several times. The muskrats have especially graced me with their presence.

12 muskrat PC173212© Maria de Bruyn res

14 Brumley pond IMG_0308© Maria de Bruyn resThat’s lucky because last year our county had its 12th driest December month on record over the past 128 years. This was quite evident at the pond, which appeared to have shrunk by at least 30-40% during the autumn and early winter drought (my estimate). I’ve been surprised to see these animals still living there.

Because muskrats don’t tolerate dry heat well, they’ve been designated an indicator species for the effects of long-term climactic drying. Recent research has shown that their numbers and response to this phenomenon should be taken into account in scientific and environmental policy-making.

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To deal with dry heat, these mammals regulate blood flow to their feet and tail through a mechanism called regional heterothermia. This enables them to keep these appendages cooler than their body’s core. Another interesting anatomical feature is the muskrats’ specialized nostrils, which they can use to trap and recycle air after removing more oxygen before exhalation.

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At this particular pond, I’ve discovered that if I wait patiently for at least 20 minutes or so without other people walking by, it’s likely that one of the resident muskrats will surface to go for a swim and/or to forage for weedy food. (They can stay submerged for up to 15-17 minutes, so patience is warranted.) It’s often the appearance of small bubbles that alerts me to their presence and location.

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Sometimes they emerge with their tails held high as if waving a signal flag – “I’m here!”

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The muskrats dive down and come up with a mouth full of vegetation which they chew while swimming or sitting near the shore. They can also eat underwater since they’re able to chew with their mouth closed because they can close their lips behind their incisors.

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Muskrats prefer to live in areas with at least 4-6 ft (1.2-1.8 m) of water where they build tunnels that lead from the pond or marsh bottom into burrows dug into banks. I now know approximately where their burrow is located as I’ve seen them emerge and submerge in a particular spot.

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Our area just had a snowfall of 2.3 inches (5.8 cm) which will be melting in the coming days. Hopefully, the next time I visit this pond it will be fuller, and the muskrat residents will have a more spacious swimming and eating area. And then they will have good reason to wave their tails in celebration!  (Apologies for the less than stellar photos as I’ve had to use a short lens lately. Hope to have my long lens back soon. The photos in part 2 of this aquatic mammal series are better!)

21 muskrat PC312678© Maria de Bruyn res (2)

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!