Feeding the Wild Birds at FRB

From our Land Steward and Raptor Care Specialist, Rosetta

I am frequently asked “what are the best feeders/seeds to attract birds to my back yard?” and “How do I keep squirrels from eating my bird seed?” Here I have outlined what we have found to attract birds and somewhat effectively deter squirrels from our feeders at Flat Rock Brook. Web sites with further information on feeders and feed to attract particular species are referenced at the end of this article.

Mixed Seed Feeders

Squirrel resistant tube bird feeders are designed to close the feed openings under the weight of a squirrel.  We have 3 of these feeders that are filled with “no mess” mixtures of shelled seed. They attract the largest variety of birds: Northern Cardinal, Blue Jay, Tufted Titmouse, Black-capped Chickadee, American Goldfinch, House Finch, and Carolina Wren.

A platform feeder with a roof and removeable metal screen tray bottom attracts the same birds as the tube feeders, but larger birds such as Mourning Doves and Red-winged Blackbirds also visit it. Unshelled sunflower seeds can be added to the mix, but keep in mind that the uneaten seeds may germinate and grow into sunflower plants in your yard.

Peanut Feeders

We use two different peanut feeders: one is a squirrel resistant tube feeder that closes under the weight of a squirrel. The other is a tubular feeder of 1/4” mesh with a clear baffle that acts as a rain cover. These feeders are especially popular with Red- and White-breasted Nuthatches, Black-capped Chickadees, Tufted titmice, and Hairy, Downy, and Red-breasted Woodpeckers.

Nyjer Feeders

Nyger feeders are tubular and contain small holes that allow birds species such as Goldfinch, House Finche, and Pine Siskin to pull the nyger (thistle) seed through them. Finches are the only birds that these feeders attract, but for the past few years, Goldfinch and House Finches have shown a preference for the larger seed in the platform and cylinder feeders. In irruption years, the Pine Siskin prefer the nyger seed.

Suet Feeders

We use three different kinds of suet feeders: a hanging cage, a tail prop feeder, and an upside down feeder. The upright suet feeders are especially popular with the three woodpecker species. Tufted Titmice, nuthatches, and Black-capped Chickadees feed at the upside down as well as the upright feeders. Suet cakes designed to attract particular families of birds can be purchased. We generally use woodpecker suet, but it doesn’t seem to matter.

Suet Plug (or Bark Butter) Feeder log

This is a log with 1.25” holes drilled about 1.5” deep and placed horizontally or vertically. Bark butter or suet plugs can be placed into the holes. The bark butter can be purchased from a supplier or homemade from a mixture of lard, peanut butter, cornmeal, and flour. This feeder is very popular with woodpeckers.

Ground Feeders

As long as the birds at your feeders spill (or deliberately discard) seeds, ground-feeding species will forage under the feeders. For the most part these are Mourning Doves, Dark-eyed Juncos, and White-throated Sparrows, but other feeder species will join them, as will grey squirrels.

Squirrel Deterrents

The use of squirrel-resistant tubular feeders is just one way to keep squirrels from eating seed intended for birds. The feeding platforms will drop under the weight of a squirrel, closing off the openings to the seed. Used alone, these are somewhat effective, but some squirrels can outwit this design. It is amazing how long a squirrel can stretch to reach seed. We have installed squirrel baffles – either cylinders or cones – on every pole that squirrels can climb. We have also suspended our feeders on wires strung from trees to a center pole about 6 feet from the ground. Plastic soda bottles have been strung onto the wires (thanks to Tenafly Nature Center for the idea). The plastic bottles roll the squirrels right off if they attempt to walk on them.

Generally, squirrels can’t jump more than 5 feet up from the ground or more than 7 feet horizontally. They are reluctant to drop more than 9 feet onto a feeder from above. Place your feeding stations with these numbers in mind to deter a large majority of squirrels. That doesn’t mean they won’t get to the seeds. Squirrels are cunning. We are still trying to figure out how a squirrel keeps getting into our platform feeder, even with multiple deterrents.

Many people who feed birds subscribe to the “feed the enemy” solution. They believe that giving squirrels their own food such as dried corn, corn cobs, or unshelled peanuts may be enough to keep them away from food intended for the birds.

In Closing…

By no means is our setup the only or even the best way to attract birds and deter squirrels. I have found that they usually work for me, but that does not mean you should do the same. I encourage you to try different types of feeders, feed, and squirrel deterrents. It will most likely become a process of continuously trying new things.

Take this as a warning: once you start, you will keep trying to attract more birds. You may find that you enjoy watching squirrels whether they are eating bird seed or food that you set out for them. You will continue to purchase or build bird feeders and continue to spend money on feed. And then it gets worse: you are hooked. You will want to find a way to store the seed so that it stays dry and uneaten by rodents, squirrels, or bugs. You will want a better pair of binoculars to watch the wildlife that comes to your yard. You’ll wake your partner or children up at 7am on a Saturday to see the bird of prey that the feeder birds attracted to your yard. You will want a better camera with a zoom lens so that you can post the photos online to show everyone the wildlife that visits your yard and to show off your photography skills. You’ll join and search for more social media groups to share bird IDs and photos. You’ll check the eBird web site to see what species people are seeing and reporting in the area. You might even get up out of your chair at the window that overlooks the bird feeder because you heard there’s a snowy owl somewhere in the area and you want to see it. (Good thing you upgraded your camera!) And before you know it, you’re – GASP! – A BIRDER!!!

Happy birding!

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Audubon Society guides to bird beeders and bird seeds:

https://nas-national-prod.s3.amazonaws.com/audubon_guide_to_bird_feeders.pdf

https://nas-national-prod.s3.amazonaws.com/audubon_guide_to_birdseed.pdf

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A View of our Birdfeeders

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Carolina Wren

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Goldfinch and House Finch

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White-throated Sparrow

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Hairy Woodpecker

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Red-bellied Woodpecker

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Dusk

Micro-organisms, Macro-personality

From our Naturalist, Siena

Thought we were done with Lichens? Nope! We are back at looking at these fungal algae!

In today’s blog, we will be talking about some special microorganisms that can be found living on lichen all over the world. As was discuss previously, lichen are found virtually everywhere. The organism we will be talking about today is found literally everywhere.

Tardigrades, also lovingly known as Water Bears or Moss Piglets, are small microorganisms that are part of the Phylum Tardigrada. With more than 900 different species, these little organisms are some of the most diverse creatures in the world and can survive in some of the most extreme living conditions in our universe.

That’s right: Universe. Tardigrades have been found living on freezing icebergs in the arctic, on plants in the tropical rainforest, and, yes, on lichen around the world. They can even survive the vacuum of space. In order to be active, the tardigrades must be surrounded by water. This makes them classified as fully aquatic organisms even though they can be found in terrestrial environments like lichen and moss. Considering their size, only a film of water is needed to sustain these creatures. However, a thin film of water is prone to drying up or freezing, which can lead to the desiccation of the tardigrades in this film. Desiccation is a state of extreme dryness or the process of water removal. If the film of water dries up or freezes, these critters have ways of surviving!

In addition to surviving the absence of water, tardigrades can also withstand temperature extremes as low as -200°C and as high as 151°C. These micro-superheroes can also survive other environmental extremes like the intense pressures of the deep ocean, high levels of salinity, or even exposure to radiation 1000x the lethal human dose. It was for all of these reasons that, in 2007, NASA brought colonies of tardigrades on a mission to expose them to the most extreme condition there is: space.

The result of this endeavor? The tardigrades survived. However, this is not the only giant leap moss-piglet-kind has made! In 2019, tardigrades crash-landed on the moon as part of an Israeli spacecraft mission! While dehydrated, these moon-bears are probably still alive, considering tardigrades can survive years of desiccation! These micro-space explorers were even brought onto the International Space Station earlier this year! Lucky they don’t need to wear tiny spacesuits!

These tough organisms are incredible and can withstand conditions we never could; yet, these micro-cuties can be found right in your backyard! Below are some photos of a tardigrade that was living in some moss and lichen from Flat Rock Brook!

To learn more about tardigrades, check out the links below:

Carleton College’s Microbial Life Educational Resources

University of Florida’s Featured Creatures

To learn more about the space exploits of these tiny astronauts, check out the links below:

Tardigrades: Water bears in space (BBC Nature)

Tardigrades: ‘Water bears’ stuck on the moon after crash (BBC News)

Ep 197: Water Bears in Space (NASA, Houston, We Have a Podcast)

A Mob of Mockingbirds

From Education Director, Rachel:

Hi everyone! We are back to the blog! We hope you enjoy this tale of a program that helped us get a little too close to wild birds…

Red-tailed hawks are fierce predators, graceful in flight and formidable in size. They catch one’s eye as they soar through the air but are particularly eye-catching when they have a smaller bird chasing after and harassing them as they fly. This odd sight is common in the spring and early summer. These small birds are participating in a behavior called mobbing. 

“Mobbing” occurs when smaller birds swoop at, attack, and work to drive away larger birds. Red-tailed hawks are often mobbed by smaller birds in their territory, but there are many other species that can be attacked through mobbing behavior. Common culprits of mobbing are blue jays, crows and mockingbirds. 

This summer, Rosetta and I had the unusual and unfortunate experience of being mobbed by Northern mockingbirds! We were stationed at a beautiful park in Jersey City to present our Birds of Prey program with our raptor ambassadors. Rosetta began the presentation with our red-tailed hawk, Jones, perched on her glove. Before long, a noisy mockingbird family had enough of our hawk’s presence. They swooped down and flew right toward Jones! Even with a human handler, the mockingbirds were bold enough to engage in mobbing behavior. Jones was ducking and attempting to fly away, so we quickly brought her  back to her carrier, gave her a nice spray-down with a water bottle (her favorite thing), and put her safely away to rest. She’s never gone so willingly into the carrier!

As luck would have it, there was a large tent set up nearby that we were able to move to for the remainder of our presentation. Program attendees followed us into the tent and we were able to present our last birds free from mobbing. From this new location, we spotted a wild red-tailed hawk that roost  on a nearby church steeple! The program attendees had the pleasure of watching the hawk in the wild, soaring high in the sky and hunting with its keen eyes. It wasn’t long until we noticed something change…the  hawk was  now being chased by mockingbirds! 

Birds of prey are not the only victims of mobbing. Some of the program attendees told stories of having been mobbed by mockingbirds while walking in nearby parks.

Given the time of year, it is very likely that mockingbirds living in the park had young chicks in their nest. They were likely protecting them against the threat of a large, predatory bird. While I understand the need to boldly protect their young, we certainly had newfound empathy for the hawks…now that we knew what it felt like to be mobbed ourselves!

Let’s Look at Lichens Again

From our Naturalist, Rosetta

Lichens can be found in every terrestrial habitat on virtually every substrate available: trees, moss, soil, rocks, and human-made substrates.

There are at least 18,000 identified species of lichen worldwide and about 3,600 in North America. The numbers continue to increase as new discoveries are made. Lichens are classified based on the fungus and fungal features.

How to Recognize Lichens

It is generally agreed that, based on their structure, there are three main types of lichens: foliose, fruticose, and crustose. A fourth type, squamulose, is not always recognized as a unique form.

Foliose lichens look like a leaf. They can be very flat, leafy like lettuce, or convoluted and full of ridges and bumps. Their top and bottom sides are easily distinguishable.

Fruticose lichens have a branched structure and look like a little bush. They can upright and shrubby or cup-like.

Crustose lichens form a crust pressed over a surface, such as a rock, the soil, or even roof shingles. They can be brightly colored like yellow, orange, and red, or dull, such as gray and green.

Squamulose lichens are often described as an intermediate between crustose and foliose lichens. They have small tightly clustered scale-like lobes like roof shingles.

When lichens are wet, they "turn on" and start photosynthesizing and growing. When dry, they "turn off", become brittle and go dormant. The simplest way to tell if lichen is dormant or growing is by looking at its color. If lichen is a dark black or bright green, chances are that it is photosynthesizing. If it is wet and pliable, that is a good indication too. If the lichen looks pale and is dry and brittle, it is dormant and will not recommence photosynthesis until the next rain or fog event.

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The Importance of Lichens

• Lichens provide habitat, food, and shelter for other organisms, and nest materials for birds.

• Many types of lichen are pioneer species on bare rock: the rock is broken down by acids that the lichen produces in a process chemical weathering. A soil base of the broken down rock and decomposing lichen is formed on the surface, providing a substrate for mosses and vascular plants to grow.

• Lichens play an important in the nitrogen nutrient cycle: they take nitrogen from the air and convert it into a form that plants can use.

• Lichens are useful in environmental monitoring. Because different lichens have varying levels of tolerance to air pollution, their presence or absence in an area are good indicators of air quality.

• Humans use lichens for food, natural dyes, medicinal uses, and décor.

The next time you see lichens on trees, soil, rocks, or anywhere else they grow, don’t remove them. They are doing their jobs in our ecosystems!

Our coverage of lichens barely scratches the surface for more detailed information, a good place to start is the USDA Forest Service web page on Lichen Biology (https://www.fs.fed.us/wildflowers/beauty/lichens/biology.shtml) and the National Lichens and Air Quality Database and Clearinghouse (http://gis.nacse.org/lichenair)

Would you like to learn about lichens?

From our Education Director, Rachel:

Lichens are a unique part of many ecosystems. You have seen them many times before but you may not have known or understood what they are. Who could blame you?! Lichens are complicated! They are formed by a symbiotic relationship between a fungi and algae and/or cyanobacteria. For the purpose of this post, we will refer to the second partner as algae but there are types of lichen that are formed by fungi and just algae or cyanobacteria and some that are formed with all three elements.  A symbiotic relationship is one in which both partners benefit. The fungus is the more prevalent partner in lichen and often tricks us into believing that the lichen we are examining is a fungus. A closer look will help to see the lichen as its own unique species.

To better understand lichens, we can break them down into their parts and consider how the symbiotic relationship helps each partner. First, consider the fungi. Fungi are unique organisms that rely on other organisms for sustenance. They are vital in the decomposition of organic matter as they break it down to provide themselves with nutrients while also “cleaning up” decaying waste. In lichens, fungi provide support and shape while also protecting the lichen from the sun’s harsh rays.  

The second partner in lichens, algae or cyanobacteria, is capable of photosynthesis so that they can manufacture their own food. When alga is paired into lichen, it creates food not just for itself but for the fungus partner as well. If cyanobacteria are part of the lichen, they can also create amino acids from atmospheric nitrogen!

Given this partnership, lichens are very successful in even adverse conditions. The protection afforded by the fungus prevents the lichen from drying out—allowing it to continue its job of performing photosynthesis. When the lichen dries out again, it can absorb water from humid air, dew, or other sources. Their efficient handling of water makes lichen viable in difficult and harsh environments. They are even seen in tundra, desert and alpine regions where life is scarce.

Lichens are an integral part of any habitat in which they are found. They aid in soil retention, often help with nitrogen fixation, and they commonly offer food and shelter to animals. In the next few blog posts we will explore the roles that lichen play in various habitats, so be sure to check back in!

Photo by Karen Dillman from the US Forest Service

This is what I imagine when I think of lichen. The shape is certainly fungus-like!

https://www.fs.fed.us/wildflowers/beauty/lichens/biology.shtml

Ation Nation

From our Naturalist, Siena

As spring is revving up, more animals can be sighted sampling the warmer weather. Most people know of the process known as hibernation. Hibernation is a process that some mammals go through during the winter months when food and other resources are scarce. While many confuse this process are “sleeping through the winter” the animals are not constantly sleeping. They slow their heart rate and their breathing to manipulate their metabolism. While many think mammals, like bears and bats, are the only animals to go dormant through the winter, many other members of the animal classes go dormant through cold weather.

Brumation is a form of dormancy that cold-blooded creatures like reptiles go through during bouts of cold weather. During these times, reptiles and amphibians often dig themselves into the ground. The painted turtles and bullfrogs in our quarry pond dig themselves into the mud at the bottom of the pond during the winter months. If you visit our pond now, you’ll notice that our turtles have started digging themselves out from the mud and sunning themselves on the logs. The sunfish that call our pond home, also go through brumation; however, they do not dig themselves into the mud. Instead, their heart rate slows to almost nothing as they slow their metabolism to conserve resources in the winter.

Another form of dormancy is known as aestivation. Many animals in hot desert climates will go through aestivation during times of extreme heat and drought. Reptiles like crocodiles will find cool burrows to go dormant in. This hot weather dormancy is a way for these animals to escape the drastic heat and conserve as much hydration until a time when they can replenish themselves. Reptiles aren’t the only ones who go through aestivation. Some mammals like African hedgehogs also go through aestivation.

No matter the term, animals have some amazing adaptations to survive extreme weather. Hibernation, brumation, aestivation: all terms to describe different types of animal dormancy. As winter comes to a close and spring starts to bloom, we’re likely to see more and more animals poking their heads out of the mud or their burrows!

Learn More about Animal Dormancy: https://kids.nationalgeographic.com/nature/article/animals-prepare-for-winter

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Who Made that Hole?

From our Naturalist, Rosetta

This is a great time of year to hike the trails through the Flat Rock Brook forest. From now until the trees leaf out, there is much to see: several species of over-wintering birds can be found, and they’ll soon be joined by their migratory counterparts. But if you miss them, it’s easy to find signs that birds and other wildlife have been in the forest: just look at the trees – on the trunks are scratches, scars and patches that have been denuded of bark. Holes of all shapes and sizes are in the trunks and branches. Many of the holes were made by woodpeckers. I’m not going to attempt to identify which species has excavated each hole, but on your next hike, maybe you can determine which woodpecker has left its mark.

Four woodpecker species are year-round residents at Flat Rock Brook: the downy, hairy, and red-bellied woodpeckers are daily visitors to our feeders and the pileated woodpecker can be found in the forest. All four species breed here. The yellow-bellied sapsucker doesn’t breed this far south, but the species leaves plenty of evidence that it overwinters here, or at least passes through. And although the Northern flicker is a year-round resident in New Jersey, we don’t usually see them until spring arrives.

Pileated woodpeckers, the largest woodpecker species in North America, are master excavators with huge chisel-shaped beaks. They forage in standing dead trees, stumps, or logs lying on the forest floor, digging rectangular-shaped holes that can be a foot or more long. These are among the most easily identified holes along our trails. The entrance hole to the pileated woodpecker’s nest is somewhat oblong to roughly triangular rather than the circular shape of most woodpecker holes. They are roughly 3 1/2” across and typically found on the main trunk of a dead tree, 15-70’ above the ground.

Smaller birds make smaller holes. The nest hole of a hairy woodpecker is typically 1 ½ - 2” wide. The entrances to their nests are just large enough for them to fit through. They excavate in dead trees or dead branches, often placing the entrance to the nest on the underside of a branch or anywhere from 4 to 60‘ above the ground.  They make smaller holes when foraging, too: they tear off bark and drill holes no more than ½”, making a wavy pattern as they weave back and forth on a trunk in search of insects.

Red-bellied woodpeckers drill nest holes about 2” wide, placed 12-20’ high. They also peck into trees as they forage.

The smallest woodpecker in North America, the downy woodpecker, drills an entrance hole about 1 ½” wide 12-30’ above the ground. They typically place the entrance hole on the underside of a dead branch or stub, often in wood that is infected with a fungus, making it soft and easy to excavate. Downy woodpeckers do not drill holes as they forage, instead they probe for insects along thin branches and stems of reeds.

Northern flickers generally excavate nest holes 6-20’ off the ground, but they can be as high as 100’. The entrance is of about 3” diameter. They will often reuse cavities that they or another species excavated in a previous year. The northern flicker is the only woodpecker that regularly probes along the ground for ants and other yummy food items.

Although the yellow-bellied sapsucker does not nest in New Jersey, there is ample evidence that it lives in the Flat Rock Brook forest during the winter. Not usually a visitor to our bird feeders, the sapsucker makes neat rows of round or squarish pea-sized holes in live trees to harvest sap. The holes are nearly always in a horizontal line, and they will drill more than one line of holes in a tree. Tree sap collects in these holes and sapsuckers lap it up with their tongues. Insects are attracted to and get stuck in the sap, providing a protein-rich meal to the birds.

By excavating dead wood as they do, woodpeckers provide important services to the forest and other living creatures. They control insect populations and speed up the process of forest decay and nutrient recycling, which provides foraging substrate to other species. The holes woodpeckers make for nesting can be used year after year, but they aren't always used by woodpeckers. Abandoned woodpecker nests provide nesting and shelter to other cavity-nesting birds such as wrens, chickadees, nuthatches, and bluebirds, or to mammals, such as flying squirrels.

Even humans are part of this cycle. By leaving dead trees, called snags, standing and not trimming dead branches, we provide the substrates for our resident woodpeckers to make their homes. As long as a dead tree or branch does not pose danger to our human visitors it is left standing. So too, are the dead trees and branches left on the forest floor, because you never know what will be foraging or living in them. And as they break down, their nutrients are returned to the soil to provide new growth and habitat.

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Spring never smelled so... Gross?

From our Naturalist, Siena:

With the snow still piled high, I’ve been looking for signs of spring wherever I can. The usual signs I would look for are the changes in bird plumage, the blooming of the red bud tree by the pond, and the blooming of the magnolia tree outside my window. Unfortunately, it’s a little too early in the year for some of those signs and the spring equinox is still about a month away. However, there is one plant that is popping up to show early signs of spring: Skunk Cabbage!

A native species, skunk cabbage can be found all over New Jersey. While the leaves look like their cabbage namesake, they won’t be seen for a little while yet. The part of the plant one should lookout for is the flower. The flowers bloom around February which means they should be emerging now!

“But how can we find the flowers? The ground is still covered in a foot of snow!”

Great question, person reading this article! Skunk cabbage is a clever little plant. As the flower starts to bloom, the plant radiates heat, which will melt any surrounding snow. This allows the plant to make room for the leaves that will eventually emerge as the season progresses. This type of plant behavior is called thermogenesis. Thermogenic plants can radiate their own heat, which makes them great homes for early emerging bees!

              “But why is it called skunk cabbage?”

Another great question! It’s called skunk cabbage thanks to the odor it produces. While the blooming flower is a nice sign that spring is on the way, the blossom also gives off the smell of rotting meat. While not so friendly to the human nose, this odor is very important for the pollination of skunk cabbage. The smell attracts insects, like flies, who mistake the plant for its smell-alike. As these insects frequent the plant, they pick up pollen, which is then deposited in the next skunk cabbage the insects visit.

It may not be the most glamorous plant and its smell is not exactly what is thought of when one envisions the smells of spring; however, the skunk cabbage is an important part of the New Jersey ecosystems. While I wait patiently for the redbuds and the magnolias, I’ll be happy to take in the sights and smells of the skunk cabbage, knowing that this is the first true sign of spring.

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Raptors in the Time of COVID

From our Naturalist, Rosetta:

When the pandemic hit and our stay-at-home orders were issued last year, our lives changed drastically. How could we keep ourselves busy, and what could we do to keep our minds and bodies fit? At Flat Rock Brook, we had to figure these things out for ourselves as well as for the animals under our care, none more so than our resident raptors. Used to attention from our visitors, the birds were suddenly alone. In the first weeks, they saw only one staff member.

We had to cancel our birds of prey programs, but we could not let the birds sit idly for months. They have been trained to be avian ambassadors to help us teach the public about their species and the importance of wildlife conservation. We were happy when visitors could return to our trails and visit the birds in the aviary. We worked with the birds as much as possible, giving impromptu programs with the birds on our gloves to anyone who would listen.

Fortunately, once restrictions on gatherings were loosened, we were able to reschedule some live programs, albeit outdoors, socially distanced, and limited in the numbers of attendees. Some programs were presented over Zoom, although some of the birds were definitely not “into” it: they do not understand the concept of looking into the camera on the computer screen. During the months of October and November, all four of our program birds made a weekly trip to a member park of the Jersey City Parks Coalition. Although attendance was limited to numbers even lower than dictated by COVID restrictions, the birds were able to teach hundreds of children and their parents all about birds of prey in New Jersey. It did our birds a lot of good, too. They remained calm and performed their “job”, even surrounded by so many people with cameras.

Hopefully 2021 will bring more opportunities for our birds to participate in full public programs as well as informal information sessions near the aviary. We’re looking forward to it, and hope you are, too!

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Let's meet on Zoom!

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Keeping up those skills

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Birds of Prey program

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Josephine was here

Where do the frogs and turtles go in the winter?

One of the most common questions I am asked during the winter is “where did all the frogs and turtles go?” Frequent visitors know of the variety of turtles and number of bullfrogs that are found in Quarry Pond. In the summer, you hear the croaks and splashes of frogs as you traverse the trail. You see turtles sitting upon a floating log in the sun. The pond is a busy place! Naturally, when the temperatures drop and ice forms on the pond, one wonders where the animals living there go.  

Frogs and turtles both hibernate in the winter. Hibernation is typically thought of as a long nap in the winter—images of a bear curled up in its den come to mind. This method of winter survival, however, is more complicated than a long sleep. Hibernation is an extended period during which an animal’s metabolism slows significantly—their heart rate and breathing slow down to conserve energy when temperatures are cold and food is scarce. Frogs and turtles both exhibit amazing feats during hibernation.  

Let’s start with frogs. All the frogs you see hopping about the pond during the summer are American bullfrogs. They get through the freezing winter temperatures by hibernating at the bottom of the pond where the temperature remains above freezing. In order to survive a winter below the surface, frogs engage what seems like a superpower to humans. Frogs can breathe through their skin. As they lay on the pond’s bottom, water runs over their skin and provides them with oxygen.  Frogs will stay just above the mud or slightly buried, occasionally swimming slowly about the pond bottom. They cannot bury themselves under the mud because they would suffocate without that contact between their skin and oxygen-rich water. They remain in this state until the spring. They require so little energy during this period that the carnivorous frog can survive without eating until the spring.

The frog with what might be the most surprising “superpower” is the wood frog. Being ectotherms (or “cold-blooded”) animals, frogs do not regulate their body temperature and rely on environmental factors to heat or cool their bodies. When temperatures drop below freezing, so does the frog’s body temperature. This puts the frog at risk of freezing. While bullfrogs move below the water’s surface where the temperature remains above freezing, wood frogs get through the winter on land— burrowing themselves into small crevices in trees, rocks or logs. Despite being exposed to below-freezing temperatures and turning into frozen frogsicles, wood frogs are able to survive. Wood frogs survive freezing because they protect their vital organs with their own version of antifreeze. Wood frogs use extra sugars to lower the freezing temperature of water in their organs’ cells enough that they are not damaged by a freeze. Thus, when the spring comes with warmer temperatures, the frog can simply thaw and continue its life cycle.

Aquatic turtles, like bullfrogs, spend the winter at the bottom of the pond where temperatures are stable. During the summer, when turtles are active, they breathe in air to their lungs at the pond’s surface. When temperatures fall and ice forms on the pond, though, the turtles cannot come up to breathe. To survive this period, aquatic turtles reduce their metabolic rate almost completely, keeping their need for energy and oxygen low. They are able to take in the small amount of oxygen needed through their skin, mouth and cloaca. At the end of the winter, the pond’s oxygen may be depleted or reaching that point. If this occurs, some species of turtle are actually able to hibernate without any uptake of oxygen. To do this, turtles go through a process that produces lactic acid, which can be harmful to their bodies. To survive this, the turtles actually neutralize the acidic waste using the calcium from their shell and bones.

Turtles and frogs are beloved all summer long, their presence in the pond is appreciated by visitors that walk by and see these animals enjoying sunny days. At this time of year these animals are deep in the pond, waiting for the ice to melt so they can head to the surface again.

Interpreting Signs

from our Naturalist, Rosetta

Last month our Director of Education, Rachel, wrote about interpreting tracks in the snow to learn what animals visit Flat Rock Brook. Prior to the snowfall, our Land Manager Brian found a different kind of sign under a tree in our forest: pellets that had been cast (regurgitated) by a large bird of prey. As a teacher, one of my favorite classroom activities has always been owl pellet dissection. So, after the snow had melted, I convinced Brian to take me to the tree so that I could collect the pellets.

Pellets are compacted masses of fur, bones, feathers, teeth, and other undigestible material in a bird‘s meal. Many scientific supply companies sell owl pellets for use in the science classroom. Pellets can be carefully teased apart and the bones examined to learn to give us insight into the diet of the owl that cast it. In the classroom, the lesson frequently involves applying the findings to produce a food web with the owl as the top predator.

Because they are readily available for and used in the classroom, you are probably most familiar with owl pellets, but they are not the only bird that cast pellets. Hawks, eagles, falcons, and several other types of birds produce pellets as well.  If you have visited our aviary, you may have noticed pellets in the birds’ enclosures. Our large birds cast pellets that are generally 2-3 inches long, and so they are easily visible on the floors of the great horned owl and red-tailed hawks enclosures.  The small birds produce pellets less than an inch long.

The casting of pellets allows a bird to make room for its next meal. They typically cast a pellet every day. Owls gulp their food and swallow smaller prey whole, ingesting all of the bones along with the flesh. These bones are only slightly digested and persist in the pellets. Hawks tear at their food and have stronger digestive juices than owls. Thus, the pellets of hawks tend to be smaller than those of large owls and they contain fewer bones.   

So, what kind of bird produced the pellets found under the tree at Flat Rock? We have several clues to tell us. Although the snow had caused to pellets to break down, the fur was still stuck to the bones when I retrieved them. Brian had seen the pellets when they were intact, and reported that they were larger pellets which means they were from a large raptor. Several of the bones were larger than the entire pellet of a small bird.

I eliminated the possibility that these were owl pellets. Since owls generally swallow their prey whole, one can often find nearly complete skeletons in their pellets, and the bones are frequently found attached to one another, especially the vertebrae. Hawks tear much of the flesh from their victims, and do not always swallow all of the bones, so I would not expect to find anything near a complete skeleton. Indeed, I found mandibles, ribs, and a few vertebrae, legbones, and toes, and only small pieces of skull.

With the help of taxonomic keys and illustrated sorting charts, it is possible to identify what the bird of prey ate, if not to the species level, but to general group to which it belongs. The largest mandible was that of a chipmunk. Although owls do prey upon chipmunks, it is more likely that a diurnal predator would prey on a chipmunk who has ventured outside of its den.

I had one more clue that the pellets were cast by a hawk and not an owl: the location of mutes (poop) around the tree. Raptors such as hawks and eagles “slice”, or squirt their poop way out behind them. Falcons and owls poop essentially straight down and don't slice. (You have probably noticed that our resident red-tailed hawks slice their mutes, as the mesh barrier is covered in “whitewash”. If one of them raises its tail with its back to you, move out of the way!) The mutes we found were not directly under the tree, but among the fallen leaves several feet from the tree where the pellets were cast as well as other trees in the immediate area.

So, given the size and contents of the pellets and the locations of the mutes, I infer that it was a hawk who cast its pellets under the tree. If I had to guess at the species, I’d say it was a red-tailed hawk because we have seen many of them flying through our forest, over the meadows, and visiting the aviary since last spring.

If you’re interested in dissecting an owl pellet on your own, they are inexpensive and easy to obtain. Owl pellet dissection should only be undertaken with sterilized pellets due to the risk of contracting bacteria or viruses. Sterile owl pellet kits are available through several online scientific catalogs. They are usually packaged for a classroom, but Home Science Tools is a good site to purchase just one or a few pellets.

If handling owl pellets is not appealing to you, check out this virtual owl pellet dissection that you can do online. It’s not as much fun, but it is much cleaner than dissecting a real pellet!

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Taking Time to Track

From our Director of Education, Rachel:

I have spent hours wandering around the trails of Flat Rock Brook, often with large groups of young people in tow. I have been fortunate enough to witness amazing forest scenes and incredible animals displaying their strength and grace. Despite this, I know that I have only scratched the surface of forest happenings. While I understand that the lives of wildlife are often hidden from our eyes, I found myself surprised and delighted by the abundance of telling animal prints and signs left by animals after last week’s snow storm.

Snow is a wonderful tool for naturalists. It preserves the tracks of animals as they pass by, allowing for study by curious humans later on. This week, our team of educators took to the woods in search of animal signs with students from our Homeschool Trifecta class. We were overjoyed that the tracking class we planned for this group occurred on a day with snow on the ground!

Armed with our ID sheets for tracks and scat (that means poop!), we ventured out to see what happened in the woods. An abundance of tracks from a red fox were spotted all around. In one exciting spot, we noticed the tracks leading up to a point where it seems to have flushed out a nearby rabbit. Luckily for the rabbit, and unfortunately for the fox, the rabbit tracks continued on through the snow. Another spot appeared to tell the story of a great horned owl hunting for rodents that scurry beneath the snow. These owls can hear the movements of their prey under the cover of snow and will quickly fly down to catch it, leaving a snow angel-like impression behind.

The role of scat in tracking efforts cannot be overlooked. Sure, it is not the loveliest thing to consider, but it does play a great role in determining what animal you are tracking! Late in the afternoon after the sun had melted much of the snow away, we went about following a set of nondescript tracks. The identifying features were all melted away. We followed the tracks, searching for one that might give a clue—can we see claw marks on any? Can we make out whether the tracks came from paws or from hooves? No. Nothing was clear. Until we can across scat dropped among the tracks! Our students searched their scat ID sheets and determined that the animal that created these tracks was a deer.

Our snow adventures came to a close but we celebrated our wonderful finds, looking forward to the next fresh snow cover. When it comes, we will be ready to search the woods for tracks before our fellow hikers come to leave their own tracks on the trail.

Interested in checking out what animals live in your backyard? Begin by studying the tracks and scat of local wildlife! Already a tracking expert? Try out this fun scat ID quiz!

Click the pictures below to see HOW we identified these tracks.

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