Let’s Nerd Out About Gardening is a twice-monthly publication for curious people who love to nerd out about gardening, farming, and nature. Come nerd out with us researched-backed deep-dives and thoughtfully curated articles delivered straight to your inbox:
Hello Gardenerds,
I may have inadvertently saved my ripening tomatoes.
Despite having a red squirrel digging beneath the straw in my potted plants and scampering along my gutters, it has not yet touched my tomato plants.
This, according to many Reddit posts when I started looking up red squirrels, is a miracle. They apparently love to take a single bit out of ripening tomatoes, then abandon it. Sometimes even having the gall to line them up on your patio.
Now, there could be a few reasons for this.
I planted marigolds (Tagete spp.) around my tomato plants, and apparently squirrels don’t like their smell. (Something has devoured my one and only pepper, and that’s planted in a container away from the marigolds.)
Or maybe they just haven’t hit my tomatoes yet, although hopefully that’s not the case. ***knock on wood***
But as I learned about the perils of red squirrels and vegetable gardens, I found one particular anecdote. Squirrels don’t just take out a single bite out of malice.
They take a single bite because it’s scorching and they’re desperate for water. And tomatoes are full of water.
(My pepper, not so much. But whatever got at it actually ate most of it.)
So what did I do? Well, when the unseasonably cold and wet month of June turned into the blazing heat of July, I set out a 12 inch diameter pot saucer under the shade and filled it with water.
I’d done it for the pollinators, adding some small stones and wood for perches. And for the birds, although I haven’t seen them use it yet.
But possibly, just possibly, I saved my tomatoes.
So let’s nerd out about wildlife ponds.
4 difficulty levels of wildlife ponds
You don’t need to go full blown pond to help wildlife. But I see people talking about one specific type of wildlife pond, when I’ve been happy to discover there’s a whole range, going from something as easy as a tray of water to something as challenging as an inground pond. You can scale up.
Level 1: Tray of water
You don’t need to get fancy or buy anything to help wildlife. So long as you have some kind of shallow receptacle (like a pot saucer or a shallow bowl) and some rocks, then you’ve got a wildlife pond.
The rocks provide places for pollinators to reach the water safely, so the waterline shouldn’t go above them.
My husband empties and refills the tray every day or two (giving some thirsty plant a drink) to keep mosquitos from hatching in the still water. When I gardened in a sunny patio, the sun evaporated the water every few days so all I did was refill it. (Incidentally, I’ve also found that there’s always 2 or 3 dragonflies hunting in my yard.)
If you don’t have any water sources in your garden (whether it’s in your yard or even on a balcony), go do this now. I’ll wait.
Got it? Great.
If you already have a water source, that’s fantastic. ⭐⭐⭐
Level 2: Birdbath
I separated this one from level 1, because while a bird bath is essentially just a pretty tray of water on a pedestal, buying a bird bath is more expensive (although you can DIY one for much less money).
You can also upgrade your bird bath with accessories that move the water to make it easier for birds to find your bird bath. They can hear the water as they’re passing by. (Moving water also helps with mosquito control.)
Drippers add fresh water to your birdbath one drip at a time. You can set one up to add fresh water from a hose, or recirculate the current bath water. While there are some aesthetic options, you can also easily DIY one by using an old milk jug (cleaned, obviously) hanging over the bath with a pinprick hole in the bottom.
Solar fountain pumps and bubblers add a spray of water by recycling the water. You can either buy a birdbath with the pump incorporated, or get a kit to add one to an existing birdbath.
You could also get a birdbath heater, but this is highly controversial in the birding community. The idea behind a birdbath heater is that it keeps a bit of water accessible to birds throughout the winter. But if the bird takes a bath, the water will freeze their feathers and keep them from being able to move.
Proponents for heaters say that birds are smart enough to know not to bathe when it’s cold.
Proponents against heaters say that birds don’t know about technology. If they find warm water, then they’ll think it must be warm enough to bathe. There have been reports that birds have done exactly this. Even if you don’t see them, they may have been able to fly just out of view before the cold set in.
Chilling.
Personally, I would not use a heater. I live in an area where ice and snow routinely bury water sources for weeks at a time. If the birds that overwinter here haven’t adapted, then they really shouldn’t overwinter here.
If you’re in an area where there’s usually water available but is undergoing an unexpected severe cold snap, then the decision gets more complicated.
If you decide to get one, cover up the birdbath so that there’s only enough room for birds to drink but not to bathe. Laying boards across the fountain with a small gap is an easy way to do this. And get one from a reputable source. Some cheap heaters found on Amazon practically boil the water.
Level 3: Container pond or mini-pond
Now we get to a gardener’s challenge — aquatic plants! A container pond is exactly what it sounds like: a pond that’s in a container. I’ve seen so many cool videos on YouTube with these. All you need is a bucket (you could also use an old sink or a half barrel), some bricks, and some aquatic plants.
Bricks inside the container provide shallow regions and steps so that if any creature should fall in, they can climb back out again. They can also make shelves for keeping plants at their preferred depths. Depending how high your container is off the ground, you may also want to add steps outside the container so little critters can easily get up there.
You also have enough room to add emerged and semi-emerged aquatic plants. The plants will really help amphibians and insects by providing places to land on, places to lay their eggs, and places to hide. The plants use up excess nutrients to keep algae in check. (I dive deeper into aquatic plants in an upcoming essay.)
Also, at this level, you have the option to keep outdoor fish. Lots of people think that fish are strictly necessary to keep mosquitos under control, but that’s not absolutely true. Other wildlife (like tadpoles and dragonfly nymphs) love the taste the mosquito larvae, while fish also will happily eat those other wildlife.
I got really excited about keeping fish in the mini-pond I’m planning. But my husband put the breaks on that. He worried that losing fish would break my heart. And he’s right.
Fish in a wildlife pond will have a short life. You can’t provide a drinking water source for birds without opening up your fish to predation.
Which I think I would be okay with so long as they’re outdoor “wild” fish. But there’s no way that I can overwinter fish outside. It gets much too cold. And I’d feel terrible if a fish that lives for several years (or, like goldfishes, up to 15 years!!!) lived such a short life. So I’d try to bring them indoors during the winter, and get attached them to them. (I get the same way about potted perennials and it hasn’t worked out yet.)
So no fish for me. If I need more control, I’ll use mosquito dunks.
If you do use fish, check that the fish you’re getting aren’t invasive. Even though they’re cut off from local waterways, birds could accidentally get fish eggs on them when bathing in your pond, or grab a fish to eat, then accidentally bring them over to the local waterway.
And always start with a few fish. Too many fish can wreak havoc on the balance you’re establishing. (More on that in the next essay.)
Level 4: Inground wildlife pond
Now, if you have enough space to dedicate to a pond, then you can build yourself your very own inground wildlife pond. This is the most time, labor, and cost intensive project on this list, which is why it’s level 4. But it’s actually a lot easier than you’d think.
The same considerations of the container pond apply here, just on a bigger scale. You want shallow areas and plants. You also want to add plants around one side of the pond for safety and to hold moisture to ensure that amphibians don’t dry out as they come and go.
You will also need to get on board with algae. There’s a lot of advice out there (one book I’m reading being one of them) that implies that any algae at all will absolutely kill your pond. Algae will deoxygenate the water, so anything living in the pond will suffocate. Which is true, at high enough concentrations.
But algae is a food source for the wildlife you’re attracting. It’s part of the ecosystem. You just need to keep it in check, like by:
Keeping enough plants to use up excess nutrients (nitrogen and phosphorus in particular) in the water.
Using rainwater to fill your pond, as nitrogen and phosphorus sadly end up in tap water.
Not using high nitrogen fertilizers or any fertilizer containing phosphorus where it can run off into your pond (few people ever need to add phosphorus to their soil anyway).
Shade the water, either with floating plants or with trees, shrubs, or grass, as algae loves the sun.
As well, you’ll want to have plenty of dead wood in the pond to provide habitat.
If you want a pristine pond with fish, I suggest getting into aquarium aquascaping. You can see the submerged plants and fish better, and you don’t have to fight or endanger herons to keep your fish from being eaten.
But do these tiny wildlife ponds actually make a difference?
Yes!
We get obsessed with doing big things, saving big wildlife habitats while letting smaller ones get “developed”. Or we think that nothing we do could possibly make a difference, so why try at all.
But tiny ponds make a difference.
A 2023 study in Urban Ecosystems employed conservation-minded residents in Hertfordshire, UK, to observe and record what species were visiting their garden water sources (including everything I just talked about here). The researchers did the same for local urban lakes. And while they found that there were some differences in species (large aquatic birds like ducks preferring lakes for obvious reasons), there wasn’t a significant difference in visitation rates. The researchers concluded that these wildlife ponds are an effective conservation action.
It may even be better to have a few smaller ponds than it is to have one big pond. You can use a combination of these different levels to provide water sources that appeal to more wildlife, like having a water saucer for pollinators and a birdbath for birds and squirrels.
Wildlife ponds are possibly the one time where “if you build it, they will come” is actually true. After all, most landscapes used to be dotted with small ponds, both temporary and permanent. Wildlife is used to searching out water sources.
✍ Join the Conversation
Do you have a wildlife pond in your garden? Have you ever considered it? Are you interested in aquatic plants?
Come nerd out with us in the comments!
Leave a comment
Happy growing,
Tanith
P.S. Here’s your extra credit reading!
📽 So Simple To Help Birds and Bees - Mini Pond or Pond In A Pot For Your Small Balcony or Garden by Amy Kelly
This is the video that got me excited about this idea. While I knew about setting out a dish of water for insects, I didn’t realize it would be so easy to make it into a “pond” with aquatic plants.
Water in the city: visitation of animal wildlife to garden water sources and urban lakes by Esther K. Gibbons, Paul G. Close, Bronte E. Van Helden, and Nicola J. Rooney (via Urban Ecosystems)
The research study I cited above. A few highlights include:
They adjusted the data based on water volume (a large urban lake is going to serve more wildlife than a water tray)
While there wasn’t much of a difference between water sources in the broader categories (all wildlife, small wildlife, small birds, and insects), they did find differences in species
Damselflies and dragonflies were more likely to visit urban lakes than garden water sources
Bees, wasps, moths, and butterflies preferred bird baths to urban lakes
50% of respondents had more than one water source in their garden.
How does wildlife find garden ponds? by Chris Baraniuk (via BBC)
If you build a wildlife pond, they will find it. But how? Flying animals and insects look for the light bouncing off the water, and listen for the sound of moving water. Dragonflies look for the differences in polarised reflected light to find the right dark or light pond to lay their eggs in. Salamanders can smell water.
Pond life: facts about pond habitats, plants, and animals by Sylvia Myers and Lisa Hendry (via Natural History Museum)
These two writers share the diverse life found in UK ponds, from the water scorpion (which breathes through its tail) to horse leeches (which eat slugs, not blood). Yes, a bit alarming at times, but very interesting tidbits.
📽Building a Wildlife Pond by Stefano Ianiro
Wildlife photographer Stefano Ianiro recently bought a tract of land in Quebec that he’s been transforming into the ideal wildlife habitat. He has many great videos, including a documentary-length video that shares his first year living and observing there, that are well worth watching. You will learn a lot!
In this video, he builds a vernal (or seasonal) pond. In the spring, runoff from the original trout pond fills the vernal pond to allow amphibians to breed free from the threat of fish.
DIY: A solar drip for the birds by Vic MacBournie (via Ferns & Feathers)
Vic MacBournie explains how she converted a birdbath with a dripper into a solar-powered recirculating drip that won’t keep overflowing her birdbath.
Pristine Ponds Be Gone! by Nancy Lawson (via The Humane Gardener)
If you want to provide a wildlife pond for amphibians like frogs and toads to breed, then you need to let go of the aesthetic fish pond. Fish eat tadpoles. You also need to allow fallen leaves and wood to stay for habitat and some algae to build up for food sources.
