As wood frogs kick off the season with a cluck and a bang, it’s time to forget “maintenance” and learn what amphibians really need (and don’t need) to thrive and successfully reproduce in wildlife ponds.
The frogsicles thawed out for the first time on February 17, announcing their triumphant return to the above-ground world at 4 a.m. Their cacophony of longing made me so happy I didn’t even care how early in the morning it was.
I did worry about how early in the season our amphibian friends had emerged, though. Here in our central Maryland habitat, Will and I don’t usually hear the lovesick male wood frogs until mid-March. Now they were awakening almost in time for Valentine’s Day. The red-tailed hawks were already pairing up too, perched together in the trees and occasionally circling above the meadow, their loud calls scaring the frogs into silence.
It had been a couple of years since I’d been able to watch the frenzied mating balls in the pond, a sight that’s simultaneously fascinating, joyful, and disturbing. Wood frog males are not exactly gentlemen; they have lots of competition and little time to pass along their genes. Exacerbating matters is their inability to discern who’s male and who’s female until they’re hugging one another.
Females don’t always survive the suffocating melee of wrestling frogs. I haven’t witnessed any frog casualties in our wildlife ponds, but I did watch a love triangle unfold a couple of springs ago, when one pair hopped out of the water—still attached to each other—and leapt down the path toward two smaller tub ponds under the tulip trees. As they headed to their destination, a third wood frog swam to the edge and propped himself up on a stone with one foot while looking on wistfully (or so it seemed). Eventually he hopped atop the rocks to watch the retreating couple for a while before leaping away on his own adventure.
Taking the Weather in Stride
In recent seasons, peak wood frog mating season here has coincided with family losses and emergencies. This year was no different, after my father-in-law was injured and ended up briefly in the hospital. But though I missed the height of the action in the pond, I came home in late February to find the beautiful results: egg masses in water lily stems and among fallen leaves and stalks.
Last week the pond froze again, and I wondered how the eggs would fare in wildly fluctuating temperatures. Wood frog adults are hardy souls who survive winters under the leaves or just below the surface of the soil by producing glucose and urea, cryoprotectants that prevent cell damage. A significant portion of their bodies freeze, and their hearts even stop beating.
Do embryos have similar protective mechanisms? Bernheim Arboretum and Research Forest has this intriguing explanation: “The mucoprotein jelly around the eggs have a melting period higher than the fluids found in the eggs. So when the ponds freeze, the jelly will freeze before the egg and will pull water out from the egg. These dehydrated eggs are more resistant to freeze and are more able to survive the fluctuating temperatures in late winter and early spring.”
Other sources note that wood frog embryos don’t meet their end when the weather gets colder; they just slow down their development. “Eggs in the center of the mass have an advantage that may explain the rush to breed,” writes biologist Scott Shalaway. “The temperature in the middle of an egg mass can be as much as 12 degrees warmer than ambient temperature, so those eggs hatch sooner than those on the perimeter.” Sometimes precocious tadpoles have another advantage; they can eat their younger counterparts around them. It’s a frog-eat-frog world out there, after all.
More than cannibalism or other natural occurrences, though, frogs suffer the consequences of human disruption and environmental destruction. Pesticides, loss of wetlands and other native habitat, the pet trade, introduced diseases, noise pollution, and climate change are all threats to their survival and well-being. On a micro level, poorly conceived pond care practices further add to frogs’ troubles.
Wildlife Ponds Don’t Need Our Obsessive “Maintenance”
I’m often asked how we manage our small ponds. The answer is that we don’t, not really—because letting nature take its course supports much more life. Unfortunately, most backyard pond sources base their advice on a different goal: pristine waters that appeal to our culture of excessive neatness but hold little value for wild neighbors. Rather than buy into the hype, consider these recommendations instead.
1) Don’t add fish unless you want your pond to be an ecological trap.
Many people think ponds are incomplete without fish to control mosquito larvae. But fish also eat tadpoles. So if your pond contains fish, frogs who lay eggs in those waters will probably be wasting their reproductive energy.
Dragonflies, amphibians, birds and other creatures eat mosquitoes and mosquito larvae. Interestingly, the only time I notice even a slight mosquito presence at our ponds is in mid-autumn, around late October or early November, when many of the animals who naturally control mosquitoes have migrated. If you have more of a mosquito issue than we do, you can try this straw-bucket method recommended by entomologist Doug Tallamy. But don’t implement such strategies in a vacuum before actually trying to create a better balance of predators and prey through real habitat.
The presence of introduced fish in ponds creates further issues, when people use netting to try to keep herons and other wildlife from eating the fish. Netting can entangle birds and snakes and end up injuring and even killing them. Nurturing habitat is about mitigating hazards, not creating or exacerbating them.
2) Choose leaves and logs over pumps and filters.
Somewhere along the way, and with the help of a product-pushing pond industry, people got the idea that ponds should be “cleaned up,” aerated and chemically treated like tap water. But a pond that lacks plants, leaves and dead wood makes for poor habitat and is an invitation for easy predation. In natural environments, “there’s a lot of structure to a pond, whether it’s the algae or emergent plants or submerged sticks,” said Cy Mott, an associate professor of biology at Eastern Kentucky University, when I interviewed him for my new book, Wildscape. “It’s rarely this pristine thing … because that’s not what amphibians require.”
Leaves falling into ponds from surrounding native trees provide cover for many invertebrates and create a substrate for plant life in the water. Plants, logs and branches add hiding places for tadpoles and aquatic insects, and they give wood frogs places to attach their egg masses.
Frogs like to breed in still water, and filters and fountains risk destroying eggs and tadpoles. In our tranquil, machine-free, chemical-free, fish-free pond, plants filter the water instead, absorbing nutrients and adding oxygen. In both our small tub ponds and our larger excavated pond, the water has stayed clear for years without any inputs except the very occasional top-off from the hose during dry spells.
3) Get rid of the lawn around the pond; it’s a death trap.
Native plants and decaying matter are just as important outside the pond, where wood frogs, American toads, tree frogs and other species seek terrestrial shelter, food and cover for most of the year. But too often I see ponds plunked down in the middle of a turfgrass barrenscape. As College of William and Mary associate professor Matthias Leu once noted in an article about his studies of American toads, “The pond is important for reproduction. But with no forest around it, the pond does not matter anymore.”
Research by a lab at the University of Maine found that amphibians avoided crossing through areas where forests had been felled and there were no more fallen leaves to provide moisture. A PhD student spent a week watching a wood frog studiously circumvent one such spot. “This frog beelined it straight in the direction of a lot that was recently clear cut for a house site,” wrote Mitchell Jones. “About 20 meters shy of the clear cut it stopped for 2 nights and then took a 90 degree turn and moved parallel to the clear cut in the forest for the next 3 nights until I lost his trail in a bog …[B]ased on previous work done in our lab and the behavior of other frogs I observed I would venture to say that clear cut housing lot made that frog change course.”
4) Let the algae be; it’s an important part of frog habitat.
While great overloads of algae (often caused by fertilizer runoff) can deplete ponds of oxygen as the algae decompose, a certain amount of algae is important to pond life. Tadpoles eat algae, for one thing, as do insects and protozoans. Algae also help camouflage wood frog egg masses from predators.
Sometimes algae are doing even more than that. Scientists have long known that the species Oophila amblystomatis has a symbiotic relationship with spotted salamanders, colonizing dense egg masses and providing needed oxygen while receiving nutrients in return. But in recent years they’ve discovered that it actually invades embryonic stem cells and tissue. The same species also colonizes egg masses of other amphibians, including wood frogs. Though the wood frog egg masses are looser and capable of accessing their own oxygen, it seems reasonable to assume that the cozy arrangement benefits both organisms in other ways.
As we head out of another cold snap and toward 70-degree weather this week, most of the wood frog eggs have hatched. The tadpoles face new dangers now as they dodge predators and one another. But at least they won’t also have to contend with fish or turfgrass or other unnecessary hazards in our backyard oasis.
Helpful Resources
We intuited our way through creating our small ponds, but later I became aware of resources that will help us with our next one:
How to Build a Backyard Wildlife Pond is an accessible DIY guide by a Theresa Berrie, a Wisconsin naturalist and gardener who was frustrated with the conventional pond advice and graciously shared her research and successes. She also shares information on her website, Our Tiny Homestead.
Building Natural Ponds by Robert Pavlis also counters most of the standard recommendations, advising readers on everything from the benefits of natural slime to the importance of still waters to wildlife. A Facebook page by the same name draws members from around the world who share ideas for small ponds like ours as well as projects that are more ambitious in scope and size; while some of the posts feature more manicured ponds, the page also draws more habitat-oriented pond builders that can help inspire your own watery wildlife haven.
Photos and videos: Nancy Lawson/Humane Gardener
Thanks for the encouraging and helpful post! You have strike-through in two places. Do you no longer recommend theses resources?
Shoot, thank you for letting me know! I have a plugin that checks for broken links, and sometimes it’s overzealous. I just fixed it and deactivated that plugin for now.
This is really informative, Nancy. Thanks for taking the time to pull it together! Thanks for all the extra resources, too.
Thanks, Marney! I’m so glad it was helpful! 🙂
Nancy, each time I read one of your posts, I want to crawl into that lovely world you and your husband have created for native wildlife and plants, and soak up the sights, sounds, and smells. I am so inspired by what you do and how you convey your messages, and am thrilled every time I see your name pop up in my email with a notice of a new post. I am going to tackle a backyard pond and hope this summer or next to have frogs, tadpoles, and algae of my own!
You won’t regret it! All kinds of life needs water!
Thank you so much, Laurie! I really appreciate hearing from you and knowing that these posts are helpful! This is one I’ve been meaning to post for a while because people often ask questions about it. Since we are still feeling our way through this process, all I can share is what we have learned so far and some resources from people who have been doing it a lot longer. It took a long time to sift through the information and misinformation, and as with everything, some things still aren’t even known about the best way to create a wildlife pond. It will be so exciting when you create one! I remember the frogs came almost instantly to ours. 🙂
This is helpful stuff. For years, I have been trying to decide whether to put in a pump and filter or not. My goal is dragonflies, which I have not yet had come…that I know of; but I do have that frog and, if he is still there, this will be his second year. I have no idea how he came to be here! : ) I will certainly check out the resources! Thanks! : )
Thanks, Susie – I’m so glad it’s helpful! Hopefully more frogs will join your friend!
Yes, but not too many friends that I can’t have the dragonfly larvae survive! : )
Birds sure enjoy the running water from the stream that is pumped into my pond. I leave it running all winter for the birds (and other critters) and it keeps ice at bay.
Hey Marnie! I do want to have an area like that for birds, too — with a bubbler or something. All kinds of birds love our stillwater pond, but I know that some would be attracted to the sound of running water somewhere too.
I too have worried about the peepers coming out too soon in the spring, thanks to climate change disrupting longtime seasonal shifts, even as I love to hear them as a sign of spring and the life force that animates them. I was relieved to hear that the eggs seem to be somewhat insulated from cold snaps. And I laughed out loud at your account of the “third wheel” frog and its wistful contemplation of the amorous pair.
Sorry to hear that you had a family emergency recently. The end of winter is hard on humans as well as other animals.
And, finally, thank you for your well-researched advice about letting things be–the aesthetic of tidiness is very overrated.
Yes, in ponds as well as yards in general! Amen!
Hi Faye, thanks so much for reading, and I’m so happy you enjoyed the articles. Yes, the transitions can be tough sometimes. Thankfully this spring has been very welcoming. <3
Nancy, just curious,what are the dimensions of your pond? I’m building a 10×5’ pond that will top out at ~300 gallons.
We had a small pond which welcomed the life of frogs.
This year the small pond site has dried up and doesn’t hold water!
We have put a hose in the area, letting water drip in the small pond area, but no luck.
I would be grateful for any advice.
Hi Nancy,
Thank you so much! We moved to a property with an acre wildlife pond- it’s happy place for frogs as is with leaves and logs and twigs and plants and algae, everything you advise. I’ve been removing invasives and planting natives. We were thinking of adding fathead minnow to the pond as heron food- we have a blue heron regularly and a new juvenile one this spring. I’m worried about the fish impact on amphibians, but was told they don’t eat tadpoles, just maybe eggs. And maybe the heron would prefer fish to frogs and lay off them a bit? I’d appreciate your thoughts, thanks!
.
Hi Kathryn! I’m guessing they are native where you are and perhaps typically found in ponds like yours? That would be one question, since it probably wouldn’t help things to add fish that wouldn’t normally be part of that environment (I mean if you’re interested in keeping as natural a pond as possible). If the herons are already coming, there must be something they’re finding there – probably the frogs? And the more eggs you have, the more frogs (or at least froglets) you might have. I wonder if you’d want to wait another year or two to watch how things play out before introducing anyone new? I’m not really sure, but those are my initial questions! 🙂
Great article. I have a small 200 gallon kidney shaped pond. No fish just plenty of frogs. We have a large live oak in our garden. I leave the leaves in my garden and they go in the pond. Should I remove some of them? I know it’s an ecosystem and I don’t why to disrupt it. Should I leave well enough alone? Thanks
Hi Kathryn, I think it should be assessed on a case-by-case basis. Over time, even natural ponds eventually fill in. So smaller manmade ponds, especially those near trees, will fill in too, and probably more quickly. Ours has been fine for four years, but this year the trees were quite a bit taller and shed more leaves. We removed some and spread it on a new planting area. It was tricky to time it because I didn’t want to do it when tadpoles and other creatures were living there, but it seemed like it wasn’t as hospitable anymore. Oak leaves on land break down more slowly, and I imagine they might stick around in water longer too, so that could be another factor. If you feel like the pond is getting a little bit full, I would try just removing a little at a time?
Hey Kathryn,
I did the same–adding fathead minnows to a pond that previously did not have any fish in the hopes it would attract herons and other birds. However I noticed that the wood frog tadpoles, at least when they first hatch, are actually small enough for the fathead minnows to fit in their mouth. I’ve been trying to figure out the best workarounds to allow the tadpoles to mature in safety from the minnows ever since (kiddy pools, dams with screens, etc.). Maybe other minnows aren’t so voracious? Golden shiners? No idea. Be cautious!
I am so sad that our green frog from last year seems to not have made it to this year. : ( I hope and pray that another will find our small water feature as a home this summer. I had no idea how much joy I had gotten from just seeing him pop his head up! : )
Oh my gosh!! THANK YOU!!! I have been wondering what to do with my pond- it’s IMPOSSIBLE to keep clean (pristine)🤪
I live in East Central Colorado-Flat as a pancake, tornados, strong winds, lots of dust. My pond is always filled with tumble weed floating on the water that have to be removed daily.
On a good note, I have gobs of adorable little toads and I want them and the birds to be happy and well cared for.. along with the honey bees.
So I’m starting this whole shebang again from scratch, and I think it will be a great relief to me, and my front yard companions💗 Can’t thank you enough for this info!!
This was great – thank you!
Question:
Do you have any information about Hornwort? I have it in my natural pond, it must have been a hitchhiker from a plant purchase because I never put it in there. It spreads rapidly and by the looks of it, I would think that it would make a great addition for habitat but my pond is not that large and I am wondering if I need to thin it or remove it completely. Your thoughts would be greatly appreciated.
Thanks
Hi Anita, assuming you’re in North America and have Ceratophyllum demersum, I think it’s considered native across the U.S. and Canada and seems great to have in a natural pond, providing oxygen and habitat. I don’t have experience with this plant, but this is my sense from checking a few reliable sources. 🙂
We have had a small natural pond until this year.
I always looked forward to the sound of frogs…
and as my poet students called them “meditation frogs…”
Now, our little pond does not hold water!
I am bereft.
We have put a hose near the area and let water drip into what was a pond, but no luck.
Any advice?
Hi Ann, I’m so sorry – there must be a leak? What is it lined with? Is it natural clay? There is a book called Building Natural Ponds and a Facebook group created by the author – they might have some ideas?
Nancy
I am new to you, having found you doing a search for pros/cons on the nimbleweed grass (for which we are doing a small trial planting).
Question about ponds. Non native cattails have moved in. Do you recommend removing them, and how?
Thank you. I have been reading and planting for birds and other wildlife since the early 80’s. I’m sorry I’m so late finding you! I have lots of your writing to catch up on. I’ve already sent 2 articles on to my husband and a young friend just beginning her landscaping business.
Thanks for all you’ve done.
Diana Dyer
Ann Arbor Michigan