31. Landscape Sustainability: Habitat Gardens
In the big picture of sustainable gardening, the creation of habitat is a major component. As you can probably imagine, the streets, sidewalks and houses we’ve built have displaced the natural habitat of all kinds of critters. But human habitat can coexist with many other types, and the design specifics of your yard can make a big difference in the amount of habitat you provide.
Habitat re-connects your little patch of green to the larger environment and gives it ecological depth. You not only get to see pretty butterflies and hummingbirds, but you also contribute to local biodiversity, and draw things into your garden that can benefit your plant life directly. By welcoming insects, birds, and even small animals into your yard you can have a garden that is more productive, has less pests and diseases, and requires less maintenance. In a word – a happier place!
How to Create Habitat in Your Yard
The first step in creating habitat in your garden is to stop using any pesticides, since those chemicals are deadly to all kinds of organisms. Start thinking in terms of controlling undesirable pests naturally with other living organisms, called biological controls. A good habitat garden will provide a home for predators that feed on pest insects, allowing both types to balance each other out. The best thing to do in your garden to create habitat is to provide a wide diversity of plants (especially native plants) in order to attract all kinds of insects, birds and other animals. The typical lawn is the least diverse planting you can have, while a mixed native grass and wildflower meadow can host quite a lot of different kinds of wildlife. Larger woody shrubs and trees are also important as perches and nesting sites for birds, and for production of other food types such as berries and nuts. You don’t necessarily have to give up all of your lawn, or completely surrender the garden to habitat, just try to design the garden and select plants with wildlife in mind.
It is often recommended to have several of a single type of plant in a cluster, avoiding a haphazard mix of many different plants. The bigger groupings provide a more abundant and reliable habitat that will keep the birds and bees coming back again and again. I do think it is worth dedicating a portion of the yard specifically to wildlife habitat, leaving it a little more wild and messy to maximize its value to critters, many of which make use of dead branches, fallen leaves and open soil. In my backyard I’ve dedicated the full width of the very back of the yard to a habitat of native plantings, conveniently forming a dense screen from the neighbor. If every backyard was like this, there would be a nice swath of habitat running through all our neighborhoods, creating a safe haven for all kinds of species. This concept is similar to the idea of a farm hedgerow, or a regional wildlife corridor.
What's In a Habitat?
In general the needs of wildlife are not too surprising: food, water, shelter, and places to raise young. Overall, providing a diversity of plants is key: try to have a wide range of bloom times, different levels of branching, a variety of leaf densities, and many seed types, and it will be easy for things to find their niche. Native plants are critical since they are part of the same native ecosystem that our native creatures evolved in. You can even go so far as to use only plants of a certain plant community to create a habitat for the exact creatures that are native to it. For water, a bird bath or other shallow basin is easy to provide, but to prevent mosquito breeding it is important to change out the water regularly. Beyond those general ideas, the specifics vary quite a bit, let’s take a closer look at some of the most popular and important organisms to welcome into your garden:
Pollinators - Bees
Pollinators are critical not only for the natural habitat, but also for the human food supply. The pollinators, most notably bees, are a critical link in our ecosystem that suffer from a variety of issues, one of which is lack of habitat and food supply. Nationwide in the U.S. we are seeing a serious decline in some bee populations, leading to “migrant worker” bees that are trucked around to different crops as they flower to ensure fruit production. This is a big issue that has many experts worried - I won’t be able to do the subject justice here, but see the References listed below for places to find more information.
Suffice it to say that in your garden, it is important to provide for the bees. This includes flowers to feed them nectar and pollen, but also water and areas for shelter. Various bees have evolved to time their emergence with the flowering of certain plants that they value for food, which is one reason native plants and native bees naturally support each other. In general it is best to have something flowering year-round as food for the bees, and the larger the patches of flowering plants, the better. The Phacelia species is one plant that I didn’t previously use but have added to my garden designs because of its value to bees. More than half the California native bees nest in the ground, and a thick mat of bark mulch will deter that, so it is recommended to have some areas of loose bare soil in the sun for bee nesting. Constructed bee hives are of course worth having if you can, and there are smaller “bee condos” and other do-it-yourself bee nesting structures that take up less space.
Butterflies and Moths
Butterfly and moth habitat is another great thing to provide in your garden, both for the health of those species and for your own pleasure. Their water needs can be satisfied with a bird bath, but they especially like moist sand where they can land and drink. Be sure to locate this in a spot visible from a window of your house for viewing. Butterflies have two main growth stages, larvae and adult butterfly, and there are different plants most suitable for each stage. Butterflies lay eggs on plants that the newly hatched caterpillars like to eat, this varies for different butterfly types. One California native plant that some butterflies find nourishing at both stages is Common Yarrow (Achillea millefolium), so that’s a good place to start. For the amazing Monarch that migrates for the winter to California, Milkweed (Asclepias species) is a primary habitat plant. Butterflies prefer to feed in the sun, which is naturally where these plants do best.
Birds - Hummingbirds
Bird habitat is perhaps more familiar to most people – trees and large shrubs for nests, the classic bird bath for water and washing, and foods like insects, berries and seeds. Everyone likes to see hummingbirds in their yards, and they do have a few specific needs. Hummingbirds dine on flower nectar as well as insects. They are adapted to access the nectar in long tubular flowers that bees and other insects can’t reach, such as Monkey Flower (Mimulus species), and Penstemons (Penstemon species). California Fuchsia (Epilobium / Zauschneria species), is especially valuable since its flowering peaks in the late summer when many other plants are dormant – remember that a diversity of flowering times is important. I can’t say I recommend the hummingbird feeder that you often see in backyards – I’ve read that it gives them an easy sugary diet that they can become dependent on, and reduces their function as pollinators.
Other Animals
Depending on the space you have and where you are, there are many benefits to having chickens, ducks, and other fowl birds around. If properly managed, they can help control garden pests like snails while providing excellent manure fertilizer and loosening the soil surface. (This gets into the topic of Permaculture which will have to wait for a future blog article.) Nocturnal creatures like bats and owls are key predators for pest insects and rodents, and you can install special boxes that they can nest in. Rabbits, pigs and even deer and raccoons can provide valuable ecological functions in a balanced ecosystem – but of course you’ll soon need more land and some farm hands if you’re not careful - ha!
I will have to say that I have mixed feelings about the amount of use my backyard habitat gets by raccoons. Like most neighborhoods, mine has an overpopulation of fat raccoons that depend largely on human trash for food and damage garden plantings, fences and other structures. Unfortunately this is a bigger problem that is ultimately due to a lack of predators, and I’m still learning about the issues and solutions. One thing to do is avoid overwatering and high water use plantings – as things dry out in the late summer, raccoons tend to dig up any remaining wet areas in their search for worms drawn to the moisture. Overall it hasn’t been that bad in my yard and I really love all the birds and insects I see out there. So I hope you’re inspired to reconsider your garden as a habitat – by creating a home for all those creatures, you’ll go a long way towards establishing a complete ecological system that should give you a satisfying smile!
References:
Bay Friendly Gardening Guide and Landscaping Guidelines
Gaia’s Garden – A Guide to Home Scale Permaculture, by Toby Hemenway
Golden Gate Gardening, by Pam Pierce (Contains a detailed discussion of beneficial insects that control other bug infestations and how to attract them into the garden)
California Native Plant Societyhttps://www.cnps.org/gardening
The Buzz Stops Here by Constance Casey, Landscape Architecture Magazine, June 2014.
Nests for Native Bees by Matthew Shepherd of the Xerces Society for Invertebrate Conservation: https://www.xerces.org/
Alameda County Mosquito Abatement District: https://www.mosquitoes.org/
University of California at Berkeley – Urban Bee Lab: http://www.helpabee.org/index.html
The Pollinator Partnership is a national organization promoting the health of pollinators, its website includes planting guides for each US bioregion: https://www.pollinator.org/
The National Wildlife Federationhttps://www.nwf.org/
There is also the North American Butterfly Association for more information on Butterfly habitat and habits: http://www.naba.org/