At 6:03 pm, President Barbara Saunders called the meeting of the Society to order. Vice-President Ken Chaya then introduced the first speaker, Kathleen Fallon, who teaches in the MFA programs of Chatham University and West Virginia Wesleyan College, and is the current President of the Mountaineer Chapter of the National Audubon Society. Her talk entitled “Vultures: The Private Life of an Unloved Bird,” began with a brief review of the status of the twenty-three species of vultures worldwide, of which nineteen are endangered, some critically. Declines have been caused by poisoning, accidental or deliberate, electrocution from power lines, and even a cultural practice that employs vulture brains as a means of achieving clairvoyance. The situation in North America is more encouraging. Turkey and Black Vultures, both protected by the Migratory Bird Treaty Act, are increasing in numbers. All species of vulture are scavengers of carrion and play an important role in maintaining a healthy ecosystem by removing carcasses before mammalian scavengers can congregate. As an example of their essential role, Katie cited an increase in human rabies cases caused by the decline in the four species of vulture in India, with a concomitant rise in feral dog and jackal populations. She also pointed out that the acidity of the vulture stomach is close to pH0, so that any pathogens are completely digested, so much so that not even DNA can be found in their excreta. For the remainder of her talk Katie concentrated on the biology and habits of the Turkey Vulture, with population numbers of some fifteen to twenty million birds. There are six sub-species, whose range extends from southern Canada to the southern tip of Argentina. Some are relatively short distance migrants, while those in the tropics are year-round residents. Unlike other raptors, Turkey Vultures have poor grasping talons and cannot take living prey. Instead, they are obligate carrion feeders, with a remarkable sense of smell and an ability to learn productive sites of roadkill. They are also remarkably lead-tolerant, so that they make excellent study subjects for the presence of environmental lead levels. Turkey Vultures nest in caves and abandoned man-made structures, with minimal nest material, and lay two eggs per year. Among their more curious characteristics is the use of projectile vomiting as a defense mechanism and so-called “urohydrolysis,” the washing of their legs with urine. Tracking devices have shown that they migrate slowly, with two of the three North American subspecies wintering in the southern states or Mexico, and returning to their summer homes in the northeast and Arizona respectively. The central Canada subspecies has been tracked as far as the Venezuelan Colombian border. In concluding her talk, Katie reviewed the reasons for the fear engendered by vultures, all of which are unfounded. They are incapable of attacking living animals and do not circle the proverbial wanderer in the desert dying of thirst. Their cartoon image is not a true reflection of their habits and does not acknowledge their essential role in the environment.
At 7:32 pm President Barbara Saunders reconvened the meeting. Recording Secretary Hamish Young read the minutes of the November meeting. They were approved as read. Secretary Lydia Thomas presented one candidate for Active membership, Dawn Hannay sponsored by Gina Goldstein. The application was approved unanimously. President Saunders announced the breaking news that the City Council had just passed a bill mandating bird-safe glass in all new buildings. The bill awaits the signature of Mayor de Blasio. She also informed members of the dates of the upcoming Christmas bird count: President Saunders reminded members that the Society now has an Instagram account @LinnaeanNY to which members can post. Seventyeight members have done so to date. President Saunders also urged members who had not already done so to pay their dues. She thanked those who had contributed to the sponsorship fund for the Annual Dinner and reminded members that tax-deductible contributions received before January 1st will be acknowledged in the invitation.
President Saunders then introduced Emily DuVal, Associate Professor at Florida State University. Her talk “Dancing Birds, Sexual Selection, and the Evolution of Cooperation in a Tropical Forest,” summarized twenty-one years of field observations and analysis of Lance-Tailed Manakins on Isla Boca Brava off the south coast of Panama. As Emily pointed out, Charles Darwin posited sexual selection as one of the driving forces of evolution. Two mechanisms were proposed. One was direct competition between males for the opportunity to mate with receptive females. The other more controversial idea – at least to Darwin’s Victorian contemporaries – was that females might exercise choice, and thus select for traits that were passed on to future generations. This raises two intriguing questions: why do females exercise choice and how is this choice exercised? Emily’s group’s research sheds light on both of these questions. Lance-tailed Manakins’ courtship behavior takes place in a so-called “exploded lek” where males display to females within a small geographic area, but in which individual courtships are separate and may only be in earshot of one another. Another odd feature is that two males, one alpha and one beta perform a song and dance display to impress the female but only the alpha will have the opportunity to mate. Painstaking analysis of the behavior of both males and females, and analysis of the DNA of parents and offspring leads to several perhaps surprising conclusions. First, alpha and beta males are usually not related, so kin selection as an explanation of why there are two males involved in the display is not supported. Seemingly obvious cues for female choice, such as brighter colors or a lower parasite load of the males, do not seem to be important either. Instead, age and experience of the males, and a greater degree of heterozygosity of the successful male, are of most importance. The greater the degree of heterozygosity, the better the chance of chick survival. This may be an answer to the “why” question. How this heterozygosity is sensed by the female is still not clear, but a working hypothesis is that volatile compounds in the oils produced by the preening uropygial gland may be the key. These volatiles may be disseminated during the energetic dance display, and the greater the heterozygosity of the male the more variety there will be in the volatiles’ composition. Emily also noted that the beta male may gain some benefit from associating himself with the dominant alpha, perhaps by learning to become an alpha later. She also presented evidence that in displays where two females are present, by-stander virgin females can learn from more experienced females in a process known as mate copy choice. In conclusion, Emily emphasized that the obvious visual cues often thought to be the dominant characteristic in sexual selection may be relics of past selection events and of no great significance in the present. Understanding the behavior of the female, and her choices, is the key to understanding this complex evolutionary mechanism.
The meeting was adjourned at 8:52 pm.
Respectfully submitted by
Hamish Young, Recording Secretary