Small mammals, big personalities

            The seed dispersal habits of small mammals have long been known to have a significant bearing on the health and growth of forests. Now a doctoral student at the University of Maine has found that the various personalities of those small mammals also determines whether seeds germinate and grow.

            “People are generally willing to accept that dogs and cats have personalities because they can see behaviors that consistently differ among individuals of the same species. The

Recording a mouse personality (Holland Haverkamp)

same is true of mice,” said Allison Brehm, who conducted a study of how the personalities of small mammals affect forest structure. “Some are consistently more active or bolder than others, and we wanted to know whether small mammal personality influences seed predation and seed dispersal.”

            She captured 648 mice, voles and shrews and put them through a series of behavioral tests that determined their timidness, docility and anxiety. Then she released them into forests undergoing three silviculture treatments, dispersed seeds of various sizes nearby, and watched what happened.

            “We know small mammals have personalities; we know they play a role in seed dispersal; but the main question was whether all individuals contribute in the same way or are some individuals playing an especially important role and does personality predict their decisions in terms of seed dispersal,” Brehm said. “We wanted to see if personality influenced their selection of seed size, dispersal of seeds, the probability of them consuming the seeds, and if it influenced where they cached the seeds.”

            And she found that in almost every case it did.

            For instance, Brehm found that mice that were especially active when compared to others were more likely to remove seeds from where they were found and consume the seeds rather than cache them. She also found that bold voles dispersed seeds farther than timid ones, perhaps because they are more willing to risk attack by predators while carrying seeds a greater distance. More docile voles, however, tended to store seeds in locations that were more optimal for germination, like close to a fallen log.

            She also discovered that the distribution of small mammal personalities differed by silviculture treatment. She captured few timid mice in even-aged forests, for example, but equal numbers of bold and timid mice in an unmanaged 100-year old forest.

            “It may be that the even-aged forest is a riskier environment to live in, so it pays off to be a bolder individual, since there may be fewer resources available and bolder individuals are better competitors,” Brehm said.

            The study suggests that it may be worthwhile to promote the diversity of personalities within small mammal populations as a way of helping to conserve ecosystems. How exactly to do that is uncertain.

            “Promoting behavioral diversity is probably best done by promoting diversity in the environment,” said Brehm. “Diverse environments will lead to a greater diversity of personality types that can survive there.”

This article first appeared in the winter 2020 issue of Northern Woodlands magazine.

Whale behaviors make them vulnerable to ship strikes, entanglements

            Recent advances in technology have allowed scientists to learn so much more about wildlife during times when the animals are inaccessible to human observation. Songbirds are now capable of wearing tiny backpacks equipped with sensors and satellite technology that are revealing insights into their migratory behavior, for instance. Even bees, butterflies and dragonflies are being tagged to track their movements.

            In the marine environment, scientists are using suction cups to temporarily attach

Breaching humpback whale (Todd McLeish)

whales with a variety of devices that capture video and audio and the depth and location of their underwater activities. That information is being used to better understand how and why whales are at risk of being struck by large ships or becoming entangled in fishing gear.

            In a lecture Feb. 13 at the University of Rhode Island’s Bay Campus, sponsored by Rhode Island Sea Grant, the research coordinator at the Stellwagen Bank National Marine Sanctuary, David Wiley, discussed the feeding strategies used by humpback whales in the sanctuary located in the waters between Boston and Provincetown and how those behaviors increase their risk of mortality.

            “There’s a sand lance culture at Stellwagen Bank,” said Wiley, referring to the 6- to 8-inch fish the whales eat. “The Stellwagen humpbacks don’t go to Jeffrey’s Ledge 40 miles away because that’s a herring area, and the Jeffrey’s Ledge humpbacks that eat herring don’t go to Stellwagen. They’ve developed these cultures that allow them to be very productive in this habitat, and they try to stay in this habitat.”

            Based on the video data collected in recent years, Wiley said the whales scrape their jaws along the seafloor to capture sand lance as the fish try to escape from their hiding places in the sediments. But he believes that the whales coordinate their behavior to improve their odds of catching a meal.

            When feeding at night or in deep water, where visibility is particularly poor, two or three whales dive to the seafloor together and orient themselves head to head.

            “You can see them almost touching each other, rostrum to rostrum, as they try to capture these fish,” Wiley said. “They do it as a group and push the fish toward each other as the fish rocket out of the bottom.”

            To further prove that this is a cooperative behavior, rather than a competitive one, he showed that the same whales almost always orient themselves in the same compass position relative to one another. Relative to a tagged whale, one untagged whale was positioned at the same angle in the feeding group 96 percent of the time, while a second untagged whale was consistently oriented at an angle between the first two 67 percent of the time.

            Wiley also collected data about the whales as they fed at the surface in a behavior called bubble-netting, when the whales blow bubbles to herd their prey together before capturing them. Again, the whales appear to coordinate their feeding by orienting themselves at similar angles and even opening and closing their mouths at the same time.

            “They orient themselves in a star formation and synchronize their engulfment, so it’s clearly a group feeding behavior and a cooperative behavior,” he said.

            In one version of the bubble-netting behavior, the whales also slap their tails at the surface in between blowing bubbles. Why they do so is a mystery.

            “They slap their tails over and over again, so it must have an adaptive value, but we really don’t know,” Wiley said. “People used to think it was to stun the fish, but we’ve never seen stunned fish. We think the percussion scares the fish and makes them aggregate into a tighter school, but we can’t really see what goes on in a bubble net because there’s so much happening at once.”

            How do these behaviors make the whales more vulnerable to becoming entangled in fishing gear or struck by ships?

            According to Wiley, bubble-netting is a feeding strategy used exclusively during daylight hours because that’s the only time when sand lance swim near the surface, and that’s when ship activity is highest. The whales feed on sand lance at the seafloor almost exclusively at night, when visibility is poorest, and they may not see the lobster traps and other fishing gear on or near the bottom. And because most fishing gear has ropes from the bottom to buoys at the surface, entanglement risk is high at whatever depth the whales are in.

            They’re vulnerable to vertical lines 100 percent of the time, Wiley said. They spend 50 percent of their time near the surface during the day when they could get struck by a boat. They spend 50 percent of their time feeding on the bottom at night where they’re vulnerable to fishing gear.

            “Humpback whale vulnerability comes from the fact that this is how they have to live. Their lives depend on being at that place in the water column,” he added. “The only way to reduce this risk is to reduce the amount of human activity that co-occurs or by reducing its penetration into the water column.”

This article first appeared on EcoRI.org on Feb. 20, 2020.

Time to go owling

            The freezing temperatures in February make it difficult to force myself out the door after dark. And knowing that I’ll be standing around outside for extended periods while trying to stay completely silent doesn’t make it any easier. But hearing just one distant hoot warms my bones and makes the experience worthwhile.

            Mid-winter is the ideal time to search for owls in Rhode Island, even on years like this one when visiting snowy owls are absent. Great horned owls, the largest resident owl in the

Barred owl (M.E. Sanseverino)

area, are already sitting on eggs or caring for nestlings, so it’s my first target species whenever I go owling. Standing up to two feet tall and with a wingspan of more than four feet, their silhouette is easily identified on a moonlit night by the feather tufts on their head that give them their common name. But it’s their low booming voice that I seek.

            I drive along forested roads, occasionally stopping to listen for a few minutes, especially where forests abut farm fields. Unlike most of the region’s other owls, which feed primarily on mice and voles in the woods, great horned owls are large enough to target rabbits and squirrels, and the forest edge is a great place to watch and listen for them. Most of the time, I hear nothing but traffic noise, an occasional dog bark, and the blood pumping through my head as I strain to hear anything resembling an owl.

            And then I hear it. The unmistakable sound of an owl. One hoot is enough to call the night a success, but when a second owl responds with a series of hoots of its own, I know I’ve hit the jackpot.

            Sometimes, instead of a great horned owl I hear the who-cooks-for-you call of a barred owl, though they are much more active a little later in the season. And rarely – like maybe only a few times in my life – I’ve heard a tiny screech owl spontaneously burst forth with its high-pitched whinny. They’re just as common as the other two species and can be found in similar forested habitat, but they seem to have much less to say. At least when I’m paying attention.

            If standing around in the dark listening – usually in vain – for an owl isn’t your idea of a well-spent winter evening, and yet you’d still like to see or hear an owl in the wild, then there’s another strategy to try. Just before dusk, stand in the parking lot of Sachuest Point National Wildlife Refuge or Third Beach in Middletown or the Moonstone Beach Road side of Trustom Pond National Wildlife Refuge in South Kingstown, and watch for short-eared owls hunting for prey over the adjacent marshlands.

The gold-and-brown streaked birds seldom vocalize, so going after dark won’t be productive. But they are regularly observed at dusk flying back and forth just above the vegetation and occasionally pouncing silently into the reeds to capture a meal. And their long wings and butterfly-like flight are so distinctive that even if you only see their silhouette, you’ll know it’s a short-eared.

A few other owl species can sometimes be detected around Rhode Island this time of year, like tiny saw-whet owls or long-eared owls – and barn owls on Block Island – but finding them is much more challenging. And the noises they make are very un-owl-like.

But if, like me, you want the most owl-like of owl encounters, all it takes is time spent listening in the forest after dark. And plenty of patience.

This story first appeared in The Independent on Feb. 16, 2020.

Drones an important tool in environmental research

            The rapid technological advances in drone technology, together with their affordability and ease of customization, has made them an increasingly important tool for scientists studying wildlife and the environment. Rhode Island researchers are taking advantage of them for such wide-ranging uses as monitoring algae blooms, assessing forest damage following storms, and creating high-resolution maps of the landscape.

            Paolo Stegagno, a new engineering professor at the University of Rhode Island, worries that some people may think that drones are the solution to every problem, and he is skeptical

URI engineer Paolo Stegagno and his drone (Nora Lewis)

that they will be effective at delivering packages or pizzas, as some companies claim.

            “But there are some tasks that drones are really useful for, tasks in which you have to reach someplace that has difficult terrain to go over or could be dangerous for people,” he said. “They can also collect a lot of data that is difficult to collect otherwise, like infrared imagery or thermal information from wildfires or from people in distress. If you select the right sensor for a specific task, you can get a better point of view of what’s going on.”

            Stegagno is working with scientists in three other states to collect data about how algae blooms develop in lakes in an effort to better predict when they might occur. That data will be shared with the Watershed Watch program, which tracks water quality in most of Rhode Island’s water bodies.

            “We don’t really have any real knowledge of what actually triggers the blooms, so we can’t predict them now,” he said. “We plan to put drones in the air and surface vehicles on the water to collect data using specific bands of light to determine the factors driving the blooms.”

            The project will begin this spring by monitoring algae blooms in Barber Pond and Yawgoo Pond in South Kingstown.

            Jason Parent, another new URI professor, is using drones to map forest characteristics like canopy density and tree mortality and to measure stem density and diameter.

            “These are characteristics of a forest that indicate forest health and tree risk to infrastructure, when they’re more vulnerable to failure during storms,” he said. “I’m using that data to help better manage the roadside forest, to reduce risk so we can invest resources in the most beneficial treatments.”

            The objective is to help utility companies and municipalities identify trees that are a threat to power lines and other infrastructure so they may be trimmed or removed before the trees fall. Parent is working with colleagues at the University of Connecticut and Connecticut utilities on a vegetation management program to manage the forest within 100 feet of the roadside by removing unhealthy trees. He hopes to initiate a similar project with National Grid in Rhode Island.

            “It’s an intense program, so it needs to be targeted where it can have the biggest impact, and drones help to identify priority areas,” he said. “Drones are limited by their battery power and other restrictions, so we use them to calibrate data collected by planes. The airborne data has lots of information, but it’s hard to interpret and you can’t get to the same level of detail as you can with drones. So we’re using drones to ground-truth the airborne data.”

            Parent is also beginning a project to use drones to map the inside of buildings to create indoor navigation systems for first responders.

            At the URI Environmental Data Center, which creates ecological maps of the entire state for a wide variety of environmental applications, drones are being used to create high-resolution imagery for use in classifying habitats and land cover.

            “We’re hoping drones will allow us to image over smaller areas and capture much more precise information at times of the year when we can call the shots and not have to wait for the state’s periodic overflights,” said Charles LaBash, director of the center, who notes that the Rhode Island Department of Transportation collects aerial photography of the state by conventional aircraft three times each year to support its stormwater management efforts and other projects. “If something is happening now, we can go up and mobilize relatively quickly. That’s the advantage of drones.”

            For instance, staff at the Environmental Data Center are using drones to monitor the progress of several efforts by the Coastal Resources Management Council, Save the Bay and others to raise the elevation of salt marshes that are threatened by rising sea levels and storm surge.

            “Drones give us a way to monitor the success of the vegetation that’s taking root out there,” LaBash said. “You can look at it with your eyes, but having that imagery gives you a consistent way to document the geospatial position and extent of revegetated areas.”

            When conditions are right, the center is also using drones to look into the water in the state’s coastal ponds to map the location of eelgrass beds. It also has used its drones to test equipment used by other researchers that detects migratory birds flying by the Block Island wind farm, among other projects.

            “There are many other possible uses of drones that we’re just beginning to think about,” said Stegagno, the URI engineering professor, “like monitoring wide areas for early detection of wildfires or for use in precision agriculture, where you collect data from crops to figure out whether your plants are in distress. All you have to do is customize them with the right sensors.”

This article first appeared on EcoRI.org on Feb. 13, 2020/