(Note: This meeting and presentation took place online, via Zoom, due to social distancing protocols prompted by the ongoing COVID-19 pandemic.)
At 7:00 pm, newly elected President Debbie Mullins called the meeting of the Society to order.
President Mullins noted that there were 50 attendees at that morning’s Central Park walk. Participants logged 50 species, including many migrating birds, five warbler species, and a first-of-spring Hooded Warbler. Members and non-members alike are welcome to join these walks by registering online.
The Birdathon in support of the Great Gull Island Project will be held on May 13 and 14. All members received an email with instructions for registering and donating to support this fundraiser.
Transactions, Volume XI, the research journal of the Linnaean Society, has been published, and a small number are available for purchase. Members may also read a free online version of the publication. The issue is dedicated to Dr. Helen Hayes for her work at Great Gull Island and includes the results of her studies of the Common and Roseate Terns.
Motion 1: President Mullins then announced the result of the online vote to approve the February 2023 members’ meeting minutes. The vote passed with 152 votes in favor and four abstaining.
Motion 2: The Society welcomed the following nine new members, with 156 members voting in favor and none opposed.
- Junuen Cho, Active, sponsored by Kathleen Matthews
- Cheryl Morrison, Supporting, sponsored by Nick Dawson
- Katharine Wodell, Supporting, sponsored by Carine Mitchell
- Hector Cordero, Active, sponsored by Ken Chaya
- Barbara Scaturro, Active, sponsored by Debbie Mullins
- Janel diBiccari, Active, sponsored by Ken Chaya
- Irene Liberman, Active, sponsored by Chuck McAlexander
- Liz Garn, Active, sponsored by Mary Beth Kooper
- John Coons, Active, sponsored by Susan E. Schuur
President Mullins noted that the Linnaean Society is committed to the diversity of our membership and thateveryone is welcome to join. Any person interested in membership may use her or any other board member’s name to sponsor their membership. More information can be found on the website.
At 7:10 pm, President Mullins introduced the speaker, Dr. Danielle Whittaker.
Dr. Danielle J. Whittaker
Dr. Whittaker is an evolutionary biologist and managing director at the Center for Oldest Ice Exploration (COLDEX) at Oregon State University (Corvallis). Her research focuses on the forces influencing animal behavior, mate selection, and evolution, from gibbons in Indonesia to the Dark-eyed Juncos of North America. Dr. Whittaker was previously managing director of BEACON, the Center for the Study of Evolution in Action, at Michigan State University.
Dr. Whittaker, author of The Secret Perfume of Birds, will discuss several studies that have contributed to debunking the long-standing myth that birds have no sense of smell and will describe the many ways that scent enhances avian life.
Using Common Scents: How Songbirds Communicate With Odors The Sense of Smell
Smell has been called the most ancient sense, and songbirds, like many other creatures, make abundant
use of it. Most birds’ primary source of odors is preen oil, secreted by the uropygial gland and used by birds to groom and maintain their feathers. By smelling this oil, birds can recognize and assess potential mates and rivals.Recent evidence suggests that the odors are produced not by the birds but by symbiotic microbes associated with the uropygial gland. Birds’ social behavior affects the composition of these microbial communities, which results in birds from the same group having a similar odor.
The chemical senses, which include taste and smell, are the most ancient and universal, and they are found in alllife forms on this planet. Even bacteria display chemotaxis, which is how they respond to chemicals in their environments. When the tobacco hornworm starts to feed on the tobacco plant, its saliva mixes with a chemical on the leaves, which then release an airborne chemical that attracts the big- eyed bug, a predator that feeds on the worm. Salmon follow pheromone trails in the water during the breeding season, and we’re all familiar with the ideathat dogs have a very good sense of smell. Smell is a power that is found in all life on Earth. And yet, there is a common misconception that birds are an exception to this rule.
This has been true for a long time. John James Audubon is one of the earliest sources of this myth. In 1826, he published a paper hypothesizing that Turkey Vultures have excellent eyesight due to an evolutionary trade-off thatinvolved losing their sense of smell. Unfortunately, although the experiments with which he backed up this theorywere poorly designed, it resulted in the persistent belief that Turkey Vultures only use their eyes to find food.
Another group of birds well known for their sense of smell is Procellariiformes, a.k.a. tube-nosed seabirds. Forexample, an albatross will fly hundreds of miles over the open ocean, guided by the smell of dimethyl sulfide from phytoplankton, to find the fish and other animals that comprise its diet. Likewise, petrels use their sense of smell to locate their ground burrows at night, even though they are sited among hundreds of other nests.
Songbirds
Historically, it has been thought that songbirds have a poor sense of smell, given their tiny nasal passages and the small olfactory bulbs in their brains. In 2006, Dr. Whittaker joined Ellen Patterson’s lab at Indiana University,where she studied Dark-eyed juncos, a widespread North American species with multiple sub- species. A prior study had discovered that Red Knots change their preen oil after laying eggs to hide their odor and make their nests less obvious to predators. Because juncos are also ground nesters, they are often the target of predation by snakes, chipmunks, and other birds. So the lab ran a similar test to determine if juncos also changed their preen oil during reproduction. What they found was the exact opposite. This inspired Dr. Whittaker to learn more about how songbirds use odor in social contexts.
Mate Attraction
Unlike moths, birds do not use pheromones to attract mates. Instead, in birds, there is a mixture of compounds thatis both species specific and individually specific. As with bird song, each species has a similar, recognizable mix, but there are differences from bird to bird.
Her first research project was designed to determine whether birds within the same species can tell the difference between male and female preen oil. The results did not show a clear attraction based on the odor ofpreen oil. Dr. Whittaker then looked into the possibility that the scent does not create the initial attraction but is used in choosing a suitable mate and avoiding the wrong one.
In many species, including humans, it has been proven that individuals are attracted to those with different MHCgenes than their own. This attraction is determined through smell. The theory is that a more diverse set of MCHgenes allows offspring to fight disease better, and several studies show that this is related to how humans smell and what smells we are attracted to.
In Beth McDougal Shackleton’s lab at Western University in London, Ontario, a study with Song Sparrowsmeasured whether preen oil odor choice reflected the difference in MHC genotype. They found a significant correlation between attraction and MHC-dissimilar, opposite-sex birds.
Reproductive Advertisement
Female chemical signals may function as reproduction advertisements. For example, female juncos’ preen oilpeaked during fertilization, showing that females use this odor to signal to males that they are ready. A similar experiment with chickens showed that female preen oil might stimulate testosterone production.
Aggression and Assessing Rivals
Dr. Whittaker conducted a study to measure aggression in Dark-eyed Juncos using a simulated territorial intrusion. The study found a strong correlation between the odor of a foreign junco and aggression, especially in males. It is understood to be related to testosterone and androgen receptors in the pineal gland.
Kin Recognition
Several studies show that parents and nestlings can recognize each other by smell—for example, adult petrels. Other studies have been conducted with songbirds. Zebra Finch chicks recognize the scent of their genetic parents, even if foster parents raised them.
It is not just chicks and parents that can identify one another. Birds can distinguish between unfamiliar kin and non-kin by smell, even if they have never met. Therefore,
Why Family Members Smell Similiar
Dr. Whittaker teamed up with a microbiologist, Kevin Tice, who studies scent glands in hyenas. Kevin pointed out that scent glands are full of bacteria, and the bacteria are actually what give the odor that hyenas and other mammals use to communicate.
The study examined the bacteria in junco glands to determine whether they produced unique odors. It was found that the closer the genetic relationship, the more similar the smell of the birds. Additionally, the mothers’ scents are more similar to those of their offspring because they are the only ones sitting on the nest. The males interact with the nestlings by feeding them, but they’re not sitting on them and physically sharing bacteria all day long.
Conclusion
Songbirds give off an odor that is present in their preen oil. These odors might be significant in mate assessment, giving information about the candidates’ quality and MHC genotype. Females can advertise through scent their reproductive readiness to get males interested in mating. A bird’s ability to assess odor can also be essential for evaluating the likelihood of aggression from a rival. An individual might choose to stay away from another bird who smells aggressive. Scent is also vital for recognizing relatives and avoiding mating with them.
The evening ended with a Q and A session hosted by Gabriel Willow, after which the Linnaean Society thanked Dr. Whittaker for sharing her fascinating research.