The Connection Between Flowers and Birds

May 22, 2024

A review by Mariette Nowak

Birds and Flowers, An Intimate 50 Million Year Relationship, by Jeff Ollerton

Pelagic Publishing, 2024

368 pages, hardcover

Much has been written in recent years about pollinators, particularly bees and other insects.  Jeff Ollerton is a noted international expert on plant and pollinator interactions; he has edited and written books on pollination, including Pollinators and Pollination: Nature and Society. In his latest book, Birds and Flowers: An Intimate 50 Million Year Relationship, he dives into the relationships between birds and flowers.

There are three major themes in Jeff’s book. I’ll use his forename here, as he does when referring to scientists because, as he says, “First and foremost they are people with names and lives of their own,” a gracious gesture on his part.

Jeff begins with the co-evolution of the relationship between birds and flowers, some 50 million years in the making. Small dinosaurs gliding through the trees gradually evolved feathered wings, and over the eons, they diversified into the more than 11,000 species of living dinosaurs that we now know as birds. Ancient fossils of hummingbirds and honeyeaters, belonging to major families of avian pollinators, have been discovered. But the oldest fossil of a bird providing evidence of flower feeding, a wren-sized bird unrelated to any existing species, dates to around 50 million years ago. Its well-preserved stomach contents contained a large amount of pollen, clearly representing the earliest known interaction between birds and flowers.

In the second major theme of the book, Jeff examines what is currently known and not known about the intricacies of bird-flower relationships, particularly highlighting the pollination of flowers by birds. I was quite familiar with pollination by hummingbirds, as are most Americans, and I have been privileged to see sunbirds in Africa and honeyeaters in Australia; major bird pollinators on those continents respectively. But it turns out there is an astounding diversity of pollinating birds of which few of us are aware. Jeff scoured the literature and found that a full 12.5 percent of birds, almost 1,390 bird species in 74 families (a quarter of the recognized families of birds), visit flowers in ways that suggest they are or may be pollinators.  And what surprises there are!  Pollinating birds range from parrots to pigeons, woodpeckers to warblers, and flycatchers to finches. We learn, for example, that Gila Woodpeckers not only eat the fruit of saguaro cactus and disperse their seeds, but they pollinate their flowers as well.  We discover that the New Zealand Kākā laps up nectar with a fringed tongue, and that lorikeets have finely divided tips on their tongues, even better adapted for feeding on nectar.  As an aside, Jeff also mentions some surprising non-avian pollinators, including a Galápagos lizard and a South African frog, a likely pollinator.

A table, arranged according to family, lists the diversity of flower-visiting bird orders and families. Jeff goes on to give brief introductions to the major families of these birds, offering details regarding various species along the way. Hummingbirds, surprisingly, are more closely related to swifts than to other common pollinators like sunbirds and honeyeaters. And the Tit Berrypecker from New Guinea has the unique habit of plucking flowers and smearing themselves with them, possibly for ornamental or medicinal uses. A lot of other fascinating and factual lore about birds is revealed in this book.

Jeff follows this section with an examination of pollination from a “flower’s point of view” and investigates the evolution of flower structure and floral rewards to entice birds to visit.  Again, he offers a potpourri of interesting observations and research to illustrate these themes. Nectar, for example, is quite complicated; it is far more than simply sugar and water. I enjoyed learning about how nectar is drawn from flowers and analyzed in the field as well as in the lab. The predominant kinds of sugars in nectar can predict whether hummingbirds or passerines are the flowers’ pollinators. And rarely, some flowers have colored nectar, with shades from blue to red to even black.  Black nectar, found in the flowers of a South African plant, results from chemical reactions “similar to those used by medieval monks to produce black ink from oak galls mixed with iron.”

Jeff also discusses pollination syndromes, sets of flower characteristics that seem to predict the pollinator of a particular flower. Bright red or orange unscented flowers with copious amounts of nectar are classically considered to be bird pollinated. But recent research has found that such pollination syndromes do not always predict a flower’s pollinators. For example, the white tubular flowers of a cactus from Argentina might typically be assumed to be moth-pollinated, but instead they were found to be pollinated by finches. And similar research uncovered surprises in Tasmania, Peru, and South Africa. Pollination syndromes correctly predicted the pollinator only 30 percent of the time.

Other topics in this book include a look at how birds’ senses, especially vision, have influenced flower evolution; the intriguing relationships birds have with such diverse organisms as yeasts, spiders, and mantids; and the unique evolution of bird/flower relationships on islands.  As Jeff discusses the research studies throughout Birds and Flowers, he always gives ample credit to the scientists for their painstaking and lengthy field work, which often takes months or years.  As he states, “Science is usually a marathon, not a sprint.”

In his final main theme, Jeff delves into the relationships we humans have with birds and flowers, as both are among the most common and colorful aspects of the natural world with which we are all familiar.  Here, Jeff discusses a variety of topics, including invasive and native species, the extinction of birds along with the plants that depend on them for pollination, and the pros and cons of feeding birds.

Supplementary feeding of birds, it seems, may reduce pollination of flowers and has been known to increase the aggressiveness of some birds towards humans. I was astonished to learn that Costa Rica has banned all supplementary feeding of animals, even hummingbird feeders. Native plants, on the other hand, are invaluable to birds, and Jeff cites a study highlighting the need to maintain even small patches of native vegetation with a diversity of blossoms throughout the year for flower-feeding birds.  The author also discusses the cultural importance of bird/flower relationships as illustrated in ancient paintings and pottery designs, as well as motifs on modern guitars and beer and wine bottles.

The author’s background as a published poet is revealed in lyrical phrases scattered throughout the book. Pollinating birds are referred to as “flamboyant and dedicated revelers.” Hummingbirds are “spangled troubadours of nectar feeding par eminence.”  He writes that older cities “wear their age like a coat, embroidered with layers of human history and natural colonization.”

Enjoy. This book is eminently worthwhile reading for anyone, scientist or lay person, who loves birds and flowers.

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Mariette Nowak is the author of the book, Birdscaping in the Midwest: A Guide to Gardening with Native Plants to Attract Birds. She served as director of the Wehr Nature Center in Milwaukee County for 18 years. An avid birder, Mariette is a past board member of the Wisconsin Society of Ornithology. She the founder and president of the Wild Ones Kettle Moraine Chapter, a native landscaping organization.