How and where do birds sleep?

There's a really interesting piece in Slate.com today about the way that birds sleep. It seems that a lot of people have misconceptions about that. They think that birds sleep in their nests. But the sole purpose of nests is to provide a place to hold eggs and chicks, and once that purpose is fulfilled, that nest is so nasty that no self-respecting bird is going to want to sleep in it.

The main concern of a bird looking for a bed for the night is to find a place that is safe from predators. A second concern may be to have some protection from the weather, but first and foremost is always the fear of predators.

The predator problem is such a threat to birds' survival that they have evolved a brain that will help them to meet it. They are essentially able to sleep while one-half of their brain stays awake and alert for danger.

This technique, called unihemispheric slow-wave sleep (USWS) allows the bird to have one hemisphere of their brain in a deep sleep while leaving the other hemisphere awake and alert. They are also able to turn USWS on and off depending on how safe their roost is. The Slate story gives the example of a large flock of ducks roosting on an open lake. The birds at the center of the flock are pretty safe and can shut down completely, while the birds on the outer edge are more vulnerable and have to keep half the brain alert.

So, birds, it turns out, sleep - it's called "roosting" as anyone who has ever raised chickens knows - in a lot of different places depending on what kind of birds they are. Big water birds like geese and ducks will generally sleep floating on the water. Big wading birds, like herons and egrets, usually will sleep perched in waterside trees. Shorebirds sleep in large flocks and utilize USWS and they are cryptically colored to fool predators. Hawks, eagles, and owls sleep pretty much wherever they want to. Grouse and quail which are favorite foods of so many predators depend on their coloring and on vegetation to hide, and they also generally sleep in flocks with half a brain awake. Woodpeckers roost in protected places like tree cavities or under roofs and bridges. Birds like crows, swallows, swifts, and starlings roost in large - sometimes gigantic - flocks for safety.

But the birds that we are most familiar with, the perching birds from the order Passeriformes, tend to roost in dense vegetation. These are our backyard birds like cardinals, sparrows, jays, and finches and around dusk you can see them flying into bushes, hedges, and trees where they will grab onto a a twig that suits them and settle down for the night.

So the next question is, how do they keep from falling off their perch while they are asleep? The answer once again is evolution. The perching birds have evolved "flexor tendons" in their legs that involuntarily clasp shut when a bird sits on a perch and they won't relax and release again until the bird straightens its leg. The grip is so tight that some birds, such as hummingbirds, have been observed sleeping upside down in apparent safety and comfort.

So the next time you see a cartoon of a little bird crawling into its nest at night and pulling a tiny blanket up to its beak, you'll know that it is just that - a cartoon. The true story of how birds sleep is a lot more complicated and a lot more interesting.

Gardening for the Birds by George Adams: A review

My rating: 4 of 5 stars

If you are interested in creating a habitat garden, a garden that fits seamlessly into your local environment and is welcoming to local wildlife, this is a book that can help you achieve your goal. George Adams' emphasis is upon attracting birds to the garden, but, in fact, his gardening method will also attract butterflies, bees, and other pollinators, small reptiles and amphibians, as well as avian visitors. It will be a place that is welcoming to them all and that is much more interesting for any humans that spend time in it.

One of the most popular hobbies in the country is feeding birds. An entire multi-million dollar industry has grown up around supplying feeders and feed to the hobbyists, but putting up a bird feeder in your yard is not necessarily the best way to attract birds or to attract a wide range of species. You might wind up with nothing but House Sparrows, which is not what most people who want to watch birds in their yards are aiming for.

A better approach is to actually put in the effort to create the kind of habitat that the birds are looking for. The author advises us to look at our yards from a bird's eye view. When we do that, we can begin to see that a bird-friendly landscape is what they are seeking. They want plants that are familiar to them, plants that provide food, shelter, and a place to raise their young. And, of course, they want a source of clean, fresh water.

In his introduction to his book, George Adams writes:

To attract birds to your garden, the backbone of your landscaping plan should be local native plants. By putting in native plants and using an organic, sustainable approach to gardening, you establish a balanced ecosystem in your yard. A greater variety of birds and butterflies will visit and linger, insect pests will be kept under control by insect-eating birds (reducing the need for harmful insecticides), and the wonder of nature will be part of your everyday living environment.

That is a succinct summary of the philosophy behind this book and the philosophy behind habitat gardening in general. It is one that I subscribe to and try to put in practice in my garden.

Adams explains that when you use native plants, plants with which birds and other wildlife are familiar, you will be mimicking their natural ecosystems. In doing so, you will provide birds with food, water, shelter, and nesting places, so that, instead of simply visiting and passing through, they will linger. They will call your garden home and you will have the bonus of observing them, up close and personal.

This book provides helpful calendars which list native plants from each region of the country. The calendars show the light needs of the plants, which animals make use of them and which months they will bloom, as well as other useful information. There are calendars for hummingbird and butterfly flowers, wildflowers, and for seasonal fruiting.

The author shows how to develop your landscape plan, according to the properties of your own particular region. He shows that even small garden spaces can create friendly habitats for birds. He also discusses some of the problems which may arise - things like nuisance birds such as House Sparrows and European Starlings, cats, and the unwelcome guests like rats and mice that bird feeders can sometimes attract.

Finally, there is a substantial plant directory, covering more than one hundred pages, which lists native plants from all sections of the country and their needs, as well as some of the birds they may attract. And there is a cross reference directory with profiles of the individual bird species, featuring wonderful pictures, which gives information about their preferred habitat and their behavior and, most importantly, what plants you can plant to attract them. 

This book, in short, gives a helpful but not overwhelming amount of detail regarding the horticulture of the plants and the garden design strategies. It features wonderful pictures of plants and birds that should be useful to both the birding and non-birding gardener. And the charts are well-organized and easy to understand. It is a book that provides a primer for anyone who is interested in creating a bird-friendly habitat in their yard. It should find a place on the bookshelves of gardeners and birders alike. And, yes, they are quite often the same people.

(A free copy of this book was provided to me by the publisher for the purposes of this review. No other compensation was given and the opinions here are entirely my own.)

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Does this sound like a book you would like to have? Well, this may be your lucky day. The publisher is offering a chance to win a free book as well as a framed pen-and-ink bird illustration done by the author. Just click on the link and enter. All it takes is an email address. Good luck!


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