Hops-itality

pacific tree frog (photo: jacki dougan, creative commons license)

Frogs, including this Pacific tree frog, could use a little help as they try to survive in the 21st Century (Photo: Jacki Dougan, Creative Commons license)

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Fifty years ago, Rachel Carson asked the world to consider a simple question: imagine springtime without birdsong.

Silent Spring addressed an unlikely subject for what was to become a best-selling book—the effect of DDT and other pesticides that persist in body tissue, becoming more and more concentrated as they move up the food chain (a process known as biomagnification). Yet nearly everyone could easily understand that their own quality of life would be diminished should they step outside one sunny May morning to find the dawn chorus had been replaced with a deafening stillness.

green treefrog (Photo: sarowen, Creative Commons license)Thanks to Carson’s courageous stand—and the subsequent public outcry—songbirds and other avian species dodged a bullet.* Now there’s another set of wild voices in the spring choir who could use a hand—the amphibians.

More specifically, frogs.

There are now over 1,800 threatened amphibian species. At least 168 species have gone extinct in the last two decades due to factors such as habitat loss, water pollution, disease, climate change, and invasive species. Additionally, many areas in the U.S. have recently experienced severe drought, and England is currently experiencing its worst drought in decades.

Many frog species depend on ephemeral (temporary) water sources for breeding since they don’t support fish that would eat the eggs and tadpoles. If the ephemeral pools dry up before the young amphibians have time to metamorphose, or if there isn’t enough rain to create pools in the first place, it can result in a missed generation… and a fragile future for frogs.

Poison Dart Frog Sitting on a Leaf (Photo: MoleSon2, Creative Commons license)Kermit the Frog spoke from experience—it isn’t easy being green… or yellow, or red, or black, or blue.

Frogs are essential to the health of wetland, riparian, and coastal ecosystems. Tadpoles feed on algae, preventing blooms that can reduce oxygen levels. Frogs consume millions of insects each year, including mosquitoes and ticks carrying diseases that threaten the health of humans, their companion animals, and livestock. A wide variety of wild mammals (raccoons, opossums), birds (herons, hawks, geese), and reptiles (snakes) rely on frogs as part of their diet.

April 28th was the 4th Annual Save the Frogs Day, established to raise awareness and funds for amphibian conservation. Since many frog species are comfortable living in cities and suburbs, I thought I would pass along suggestions for homeowners who would like to offer some hoppin’ hospitality, courtesy of yesterday’s event organizers:

1.    A Wet Welcome Mat

Fall and spring are the best times to create a permanent oasis for frogs. Kits are available at many garden and home improvement stores, or simply use a container or dig a hole that is deep enough (at least 1 foot at one end) and line it with sand or a flexible plastic liner before adding water.  Keep in mind, you must provide a sloped ramp so the frogs can get out easily.  Slope the liner or build one out of rocks to gradually allow the frogs to get to ground level or out of the pond. (Some nurseries also have floating devices for swimming pools that can allow amphibians who might jump in a way out.)

Don’t clean the water. In fact, add floating plants such as lily pads or leaves to provide cover. Refill slowly and carefully if water levels get low.

Don’t put fish in your pond, as they will munch on your tadpoles and frogs.

2.    Shade & Shelter

Place your pond in a shady spot, preferably surrounded with native plants to attract a tasty bug feast of ladybugs, bumblebees, and other pollinators to also help beautify your yard. You can stack some rocks or turn over a half of a flowerpot beside the rim of the pond to give your frogs a place to sit and eat their lunch as it flies or crawls by.

glass frog (Photo: Josiah Townsend, Creative Commons license)3.    Go Organic

Don’t use pesticides or weed killers. Amphibians absorb water—and any chemicals in it—through their skin. Pesticides and weed killers can run off from land into water and can be lethal to amphibians. Certain weed killers also can alter hormones, changing male frogs into females and reducing the potential of frogs to perpetuate thriving populations.

4.    Patience, Grasshopper

Don’t be tempted to relocate frogs from other areas or stock your pond from pet stores. You may introduce diseases or invasive species and domestically raised frogs will not necessarily adapt to wild habitats. If you build it, frogs will come.

5.    Look & Listen

Become a frog watcher. You will appreciate these wonderful animals more if you can see them in action, and you can help their conservation in the process. The National Wildlife Federation’s Wildlife Watcher program allows citizen scientists to contribute to a growing database of North American wildlife, learn about the animals living in their region, and build a printable checklist of sightings.

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* Although the focus of this post is frogs, wild birds still face many challenges and threats to their long-term survival. You can check out one such hazard here. Others will be addressed in upcoming NDN posts.

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© 2012 Next-Door Nature—no reprints without written permission from the author (I’d love for you to share my work; all you have to do is ask). Thanks to these photographers for making their work available through a Creative Commons license: [from top to bottom] Jackie Dougan (Pacific tree frog in rose); sarowen (green treefrog); Sascha Gebhardt (poison dart frog); ucumari (bullfrog); Josiah Townsend (glass frog).

Yawn

arctic fox by emma j bishop cc

There’s nothing quite as contagious as a yawn* (Photo: Emma J. Bishop, Creative Commons license)

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Grab forty winks. Saw logs. For a species that’s habitually short on shut-eye, we humans sure have come up with myriad ways to talk about it. We also spend a lot of time and money studying sleep, or the lack thereof. Yet, in spite of decades of inquiry, researchers still don’t have a good fix on why we—and just about every other living creature—need to nod off.  We’ve had better luck trying to understand other unconscious states, especially those employed by certain non-human species to deal with hard times.

yawning prairie dog by SearchNetMedia ccWinter poses a critical challenge for animals who stay put rather than migrate to warmer climes. Thermoregulation requires calories, but many foods—especially fruits, nectars, vegetation, and insects—are scarce when the days are short. The ability to reduce one’s energy needs can be a life-saving adaptation. Hibernation does just that—it lowers an animal’s metabolic rate. If all goes well, this period of inactivity, which may last several days, weeks, or even months, depending on the species, will stretch stored energy reserves (aka body fat) long enough for the animal to survive until a greener season. “If” depends on many factors, such as the abundance of autumn food resources, the length and severity of cold days, and even the stability of the den site during repeated freeze-thaw-freeze cycles.

When a critter—let’s use the chipmunk (Tamias spp.) as an example—transitions into a state of hibernation, its body temperature drops to near freezing, breathing becomes so shallow as to be imperceptible, and the heart rate decreases dramatically, from 350 to 4 beats per minute.  Although we tend to think of hibernation as a season-long slumber, chippies and other hibernating rodents do wake up every few weeks to have a snack and take a potty break, even though these periods of activity, called interbout arousals, consume up to 90% of stored body fat. There are some champion nappers in this chisel-toothed group—including the groundhog (aka woodchuck, Marmota monax), who sleeps half its life away, setting the alarm for March when it heads to bed in September.

Other examples of sound sleepers include: insectivores like the European hedgehog (Erinaceus europaeus) and the tenrecs (Microgale spp.); the mountain pygmy possum (Burramys parvus)—the only hibernating marsupial; and the echidna (Tachyglossus spp.), a monotreme.  Biologist recently added the mouse lemur (Microcebus spp.) and the fat-tailed dwarf lemur (Cheirogaleus medius) to the hibernator roster; prior to this discovery, we didn’t have any examples from among the primates. Additionally, since winter temperatures in their native Madagascar may reach 86° F (30° C), it’s become clear that hibernation isn’t strictly associated with cold weather. Nor is it limited to mammals; a bird called the common poorwill (Phalaenoptilus nuttallii) snoozes through at least some of the snowy season.

yawning polar bear by Paul Davidy ccIronically, that most famous of North American sleep icons, the bear (Ursus spp.), is the subject of much debate. The question is whether or not they are “true hibernators.” Bears often spend far more time sleeping than the so-called “trues,” so what’s all the fuss about?  Well, this is going to sound like nit-picking, but here goes. First of all, a bear’s heart rate drops, but not quickly enough to suit some scientists. Also, while the number of heartbeats may go as low as 8 per minute, the average is closer to 50 per minute. Moreover, during this time the bear’s body temperature remains pretty close to normal. This is a handy little idiosyncrasy that, should the need arise, allows the animal to wake up fast… and often cranky—a fact Santa (and anyone else) should keep in mind when planning a mid-winter visit to the den.

Taking to one’s bed for months on end could be seen as a rather over-the-top response to a simple cold front. It smacks of swooning characters in English romance novels from the late 1700s. Frankly, it’s not everyone’s cup of tea, and many wild critters take a more measured approach. Torpor is the term commonly used to describe these shorter, less dramatic forms of dormancy, although, technically, hibernation and other types of suspended animation are really subsets of torpidity. Call it what you will, there are examples of “temporary hibernation” in all the Classes of vertebrate animals—mammals, birds, reptiles, amphibians, and fish—and it’s commonplace among the myriad spineless critters.

For some of the busiest bodies, torpor is a daily habit. Hummingbirds (Trochilidae), for example, have such a high metabolic rate that they need to ingest a steady stream of non-carbonated sugar water (i.e., nectar) during their waking hours or they’ll become hypoglycemic and are too exhausted to fly. Can’t fly? Can’t feed. It’s a vicious circle that will ultimately lead to the bird’s death without some kind of intervention. As you might imagine, this need to constantly refuel creates an enormous problem when night falls and these feathered perpetual motion machines must rest. Without some way to temporarily lower their metabolic rate, hummingbirds would never be able to get out of bed in the morning. Never fear—torpidity to the rescue!

rock dove yawning by Tatiana Bulyonkova ccSwifts (Apodidae), chickadees (Paridae), nightjars (Caprimulgidae), and doves (Columbidae) are just a few of the other avian species who go torpid under various conditions. Generally speaking, these birds are fruit-, nectar-, or insect-eaters, and they tend to be on the small side (less than 80g). The snowy owl (Bubo scandiacus), at 1600-2950g is one exception to this rule, and biologists recently added a second, when it was confirmed that the tawny frogmouth (Podargus strigoides) goes torpid during Australian winters.  Personally, I find these new insights into animal behavior thrilling, because they reassure me that what we know about wild creatures is still a drop in the bucket compared to what we don’t know—there are worlds upon worlds waiting to be discovered on this blue gem of a planet we call home.

yawning turtle by Michael Ransburg ccOf course, cold is not the only hardship wild things would rather sleep through. Periods of drought are just as serious a threat to survival, especially for aquatic and semi-aquatic species. When a lake, pond, or stream goes dry, the inhabitants need to dig in. Literally. Turtles and tortoises (Testudines), crocodiles (Crocodylidae), frogs and toads (Anura), salamanders (Caudata), and some crustaceans will aestivate (also spelled estivate)—a drought-driven form of hibernation. They sink down into the mud before it dries completely, sealing themselves in a mucous capsule until the rains come again. If ever there was a time to be glad you can absorb oxygen in the soil through your skin, this is it, because the air in your boggy bubble won’t last very long.

yawning snowy owl by Pat Gaines ccResearchers are intrigued by these alternate forms of sleep and how they might offer clues for solving a variety of human health concerns. Honestly, I understand their fascination but I don’t know how they stay awake long enough to collect any data. Just writing about dormancy has my eyelid feeling so… heavy. I guess it’s… time for…. me to turn… in.

…..Hit the  YAWN!  hay.

……….Catch some…..zzzzzzzzz

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*Pop Quiz:  How many times did you yawn while reading this? 😉

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There’s nothing quite as invigorating as finding a little Next-Door Nature in your email inbox—click the “subscribe”  link in the upper right-hand corner of this page and receive notifications of new posts!
© 2011 Next-Door Nature—no reprints without written permission from the author. Thanks to these photographers for making their work available through a Creative Commons license: SearchNetMedia (prairie dog); Pau Davidy (polar bear); Tatiana Bulyonkova (rock dove); Michael Ransburg (turtle); and Pat Gaines (snowy owl).

Froggy goes a-courtin’

wood frog

The wood frog has a large North American range (Photo: Garrett and Kitty Wilkin, Creative Commons license)

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My mole Tboy (that’s spy, not insectivore) tells me Valentine’s Day has had its intended effect on the wood frog population in southwestern Virginia. On February 18th the first early-bird male appeared at a nearby pond, floating patiently and quietly. Four days later, 50 guys had found their way to the gene pool and were warming up for karaoke and the start of happy hour. Any time now, the ladies will arrive and that joint be jumpin’!

The watering hole has been silent for the last few months. Winter is a time for amphibians to lie low. Really low. Aquatic frogs hibernate on or partially buried in the mud at the bottom of ponds and lakes. Terrestrial frogs, including the wood frog, hibernate on land. Some burrow down below the frost line, but wood frogs are not adept diggers so they seek out crevices in rocks, crawl beneath a log, or just huddle in the leaf litter.  These hibernacula don’t always make for a cozy inglenook. When the temperatures drop below freezing, so do the wood frogs. But not to worry—wood frogs have what it takes to best Old Man Winter.

Antifreeze.

No, I’m not talking about well drinks. A high concentration of glucose keeps the frog’s vital organs from freezing, so even though the animal stops breathing and doesn’t have a heartbeat, it’s not dead. As soon as things heat up again, the frog thaws and life goes on.

wood frogs in amplexis

Wood frogs in amplexis—male is on top (Photo: Richard Bonnett, Creative Commons license)

The wood frog club scene is cool. That’s because it usually begins in January or February, sometimes before the ice has disappeared from vernal reproduction pools. The whole rave lasts for about two weeks. A female steps onto the dance floor—I mean into the water—and a male grabs her and holds on tight. The process is called amplexis. That’s Latin for embrace. Yeah. Kind of like the way sumo wrestlers embrace.  Because once the male has her in his arms, he’s not letting go without a lot of… persuasion. Sometimes not even then.

wood frog egg massesThe process is highly competitive and not without hazards. “Satellite” males hang out beyond the water’s edge so they can grab a gal while she’s in transit. In this way, he avoids jostling with the boys at the pool while also scoring a ride to the party. Also, male wood frogs are stimulated by movement so they’re not always discriminating about who they grab. Sometimes they grab the wrong species of frog, and sometimes several males will grab the same female. This can cause her to be squeezed to death or drown.

But, assuming there aren’t any bar brawls, the female will lay large masses of 1500+ eggs, choosing a site where they receive sunlight and protection from predators. When she releases her eggs, the male—who has been waiting for this opportunity and is now in the perfect position—fertilizes them with a sperm-containing fluid and soon the eggs begin to develop.

wood frog metamorphosing

Eventually, the tadpoles hatch and begin their metamorphosis, absorbing the nutrient reserves in their tails to fuel their makeover.

wood frog metamorphosingTime to head for the forest and get on with the serious business of making a living. Last call! (Until next year, that is).

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© 2011 Next-Door Nature— no reprints without written permission from the author. Egg mass photos by Richard Bonnett; metamorphose photos by Brian Gatwicke. Thanks to all the photographers featured in this post for making their photos available for use under a Creative Commons license.