(NOTE: This meeting and presentation took place online, via Zoom platform technology, due to social-distancing protocols prompted by the ongoing COVID-19 pandemic)
At 7:00 pm, President Ken Chaya called the meeting of the Society to order. He welcomed the attendees before thanking the Council, Committees and past Presidents for their continued help this year.
He then reminded the audience that more information about Linnaean programs and field trips—now in progress with safety guidelines in place—could be accessed on the LSNY website.
President Chaya also reported the recent loss of the Society’s oldest member, Michael Burke Flynn, age 100, who first joined the LSNY in 1937. Michael passed away at his home in El Paso, Texas on October 26, 2020. This past year, his daughter, Bonnie, told the Society that each year, he never failed to insist upon renewing his Linnaean Society membership. On behalf of the Society, President Chaya expressed condolences to his family and friends.
President Chaya reported that the American Museum of Natural History has cancelled all program events through the end of the year and that it is not yet known when the Society may return to presenting its programs at the Linder Theater. Until then, we will continue to bring our programs online on a monthly basis. He announced that the business portion would start the meeting and that the program would follow.
The results of the online poll taken at last month’s Zoom meeting was announced. In response to the question if attendees would prefer one (1) or two (2) meetings with speakers each month, there were 92 votes for two meetings and 39 votes in favor of a single meeting. President Chaya expressed his pleasure that the meetings have struck a popular note with attendees, but that to conduct two speaker meetings each month would/will require a great deal of work and that the Society is run by volunteers. So, the matter will need to be considered further before a decision is made. If such a change is made, however, it would not take place before sometime in 2021.
Because the Society’s membership recently took the opportunity to vote online via email, there were only three business items on the agenda. The first item was the result of a vote on the approval of new members. It passed with 79 votes of approval and none of disapproval. President Chaya then welcomed the following 11 individuals as new members:
- Beatrice Schwartz, Active Membership, Sponsored by Miriam Rakowski
- Jean-Paul Picard, Active Membership, Sponsored by Mary Picard
- Donna L. Schulman, Active Membership, Sponsored by Mary Normandia
- Gillian Henry, Supporting Membership, Sponsored by Victoria Seabrook
- Sally Kopstein, Active Membership, Sponsored by Nancy Shamban
- Mary Ann Zovko, Active Membership, Sponsored by Kevin Sisco and Kathleen Heenan
- I.C. Levenberg-Engel, Active Membership, Sponsored by Gabriel Willow and Ruth Hart
- Lenge Hong, Active Membership, Sponsored by Gabriel Willow
- Chee Wok Yong, Active Membership, Sponsored by Nancy Shamban
- Michele Truong, Active Membership, Sponsored by Crystal Thiele
- Sylvia Paredes, Active Membership, Sponsored by Chuck McAlexander
He then invited non-members in attendance to join the Society and explained how they could do so by visiting the LSNY website, www.linnaeannewyork.org. Additionally, he offered that he, personally, would be willing to sponsor anyone who would like to join, commenting that an organization is only as healthy as it’s growing and diverse membership.
The second item was the result of a vote to approve the minutes from both the September and October meetings. It passed with 79 votes of approval and none of disapproval.
The third and final item of business was to announce the request for nominations for a new Council member to replace Amy Simmons, who created a Council vacancy when she became Recording Secretary of the Society. Nominations were requested from the floor and were to be sent directly to President Chaya at president@linnaeannewyork.org by 9 p.m. that evening.
At 7:11 p.m., President Chaya introduced Matthew Combs, who earned his Ph.D. at Fordham University in Bronx, NY, studying the ecology and evolution of brown rats in urban landscapes. His work leverages genetic and modeling tools to understand rat migration dynamics and their influence on zoonotic disease. Matt has worked with the New York City Department of Health and Mental Hygiene on their rat control efforts and promotes the inclusion of biological context in management strategies. He currently works as a Postdoctoral Research Scientist at Columbia.
The subject of his talk was, “Rats in the City: Ecological and Conservation Implications of a Global Pest.” His focus was on the brown rat (Rattus norvegicus), which has successfully invaded cities and islands across the globe, causing major public health risks and conservation concern.
Matt began his talk by highlighting how different species of animals respond differently to the urbanization which occurs in cities, with Brown Rats (also sometimes inaccurately referred to “Norway Rats”) being among the animal species that actually thrive in an urban environment. Also, due to the global pattern of urbanization, there is an opportunity for replicated study throughout the many major cities that have significant Brown Rat populations.
Brown Rats are “opportunistic generalists” in terms of diet and habitat: they will eat what is available and are flexible enough to live anywhere they can create a small nest. Breeding quickly (gestation period of only 21 days), Brown Rats give birth to 8-10 pups per litter, but have fairly short life spans (most in NYC only live for about a year.) They are quite intelligent, responding quickly to change and able to learn from one another about new food sources and dangers. They are also rather social and can change their behavior to fit their current environment. With well-adapted physical abilities for navigating a city, they can gnaw through asphalt, climb, dig and chew through aluminum and cement. In short, they can access cities in ways that other animals cannot.
Matt then listed some of the more popular myths about rats, also providing facts to debunk them:
Myth: “Rats are as big as cats”
Fact: Most rats have an average weight between .5 and 1.5 lbs., with a maximum weight of 2 lbs. and a body size of 7-10 inches. Matt shared that the largest rat he has ever caught weighed 1.75 lbs. (and its body is now at the Yale Peabody Museum.)
Myth: There is one rat for every human in NYC.
Fact: Rat populations fluctuate with the seasons, peaking in spring/summer, but estimates are 250K to 2M. A more realistic ratio is 1 rat for every 36 people. He noted that rat numbers started increasing in 2015 but that this was more likely due to a change in the methods for reporting rat complaints (via text) than in any true increase in rodent numbers.
Myth: Rats can flatten their skeletons.
Fact: Rats cannot flatten their skeletons, but they do have hinged ribs. They are limited by their skull size, which is about ½”, or the size of a quarter.
Myth: Cats can reduce rat populations.
Fact: While studies have shown that the presence of cats impacts rat behavior, they have also shown no impact on population size.
He then asked the question, “Why worry about rats?”, and listed three major reasons:
Public Health – Rats carry a variety of viruses (i.e., Leptospirosis, Bartonella, Seoul Hantavirus), as well as ectoparasites (i.e., Tropical Rat Mite, Spined Rat Louse, Oriental Rat Flea)
Infrastructure damage – Rats can chew and gnaw on support structures and create significant damage
Environmental Health – The poison used to reduce rat populations can end up poisoning animals higher up the food change (hawks, herons, foxes, etc.)
Having established why cities need to think about and address their rat problems, Matt then pivoted to summarizing the challenges we’re facing and what science can do to help:
Rat distribution – abundance across variable social and ecological conditions such as density of brick sewers, building age, distance to subway line. His research compared those variables with the prevalence of rats in the city, as measured by DOHMH rat inspections and looked for correlations. Results showed that landscape variation predicts differential rat abundance. The age of a building was the greatest predictor of its likelihood of having rats. Other contributing factors to higher rat prevalence included (but were not limited to) the amount of green space (very low amounts of green space and very high amounts of green space were least appealing to rats, whereas ‘middle amounts’ of green space proved to be the ‘sweet spot’ for rats) and median income (lower income areas tend to have higher rat infestation.) As the Department of Health has limited resources, science can help determine what is most effective (i.e., focusing on older buildings in lower income areas) and what the highest priorities should be when faced with limited budgets.
Population Connectivity – dispersal behavior and movement barriers. From trapping rats throughout NYC and analyzing their DNA, Matt’s research looked at relatedness among rats, finding that it drops quickly with increasing distance: at 200 meters there are elevated levels of relatedness; at 200-1600 meters rats are less related, but more related than they would be at random; past 1600 meters, rats are no more related to one another than random individuals would be.
His research also indicated that there were fairly distinct rat populations corresponding with the various neighborhoods throughout the city, with Midtown showing the most inbreeding and least genetic diversity. In contrast, rat populations in Inwood, the Upper East Side, Upper West Side and Downtown showed much greater genetic diversity. (As a side note, Matt remarked that the media had fun with the concept of “Uptown and Downtown Rats”)
The Midtown habitat supports lower rat densities likely because it is less residential and more transient, resulting in less household garbage (which is also picked up more quickly.) In the surrounding areas, there are more backyards and alleyways to create opportunities for rats to be successful. With lower rat density in Midtown, it is also harder for rats there to pass along their genetic material. So, science tells us that we need to be treating for rats across entire neighborhoods, not just individual properties, and that movement barriers create natural management units which we should use to our advantage.
Adaptations – evolutionary response to cities and rodenticides. To look at how rats have adapted to cities and human environments, research was done comparing the genetic material from rats from their site of origin (the wild grasslands in northern China) to those in cities and looking for new traits that they have evolved. A genome scan was done for evolutionary signals of adaptations and they were found around locomotion, diet and metabolism. Urban rats showed adaptations in their muscular and skeletal systems for urban traversing; in their diets by way of higher fat/protein content and in their metabolism in the form of an ability to detoxify exogenous chemicals (i.e., rodenticides.)
Matt spoke about the history of rodenticides, starting in the 1940’s and ending with the introduction of 2nd generation rodenticides in 1975, which take longer to work, causing rats to become sluggish and making them attractive and easy targets for predators who then become poisoned, themselves. Eighty-four percent of dead raptors from NYC that were sent to the DEC tested positive for anti-coagulation rodenticides from 2012 -2015. Multiple bird species have been poisoned, including Red-tailed Hawks, Peregrine Falcons, Barred Owls, Snowy Owls, Black-crowned Night-herons and others.
He also spoke about the importance of implementing an Integrated Pest Management (IPM) approach to be effective and looked at why current approaches aren’t effective. Culling rats without a change in environment creates a population rebound (i.e., using poison but failing to remove garbage.) He listed the following approaches as important to an effective IPM:
Resource (trash) reduction – difficult in NYC, but proven effective elsewhere. We need a real sea change in how we deal with trash.
Habitat modification – Reduce harborage around plantings & buildings; need to make difficult choices by way of aesthetics and function
Non-rodenticide population reduction – dry-ice, reproductive control, genetic engineering.
Legislative and regulatory changes – i.e.,California is even considering a ban on rodenticides.
Constant vigilance and repetitive treatment – although can be expensive and laborious.
Matt’s final takeaways:
- Rats are fascinating and talented, but pose real risks for cities and people.
- Rat abundance is associated with buildings, income, green space
- Rat populations split uptown and downtown in NYC
- Rats appear to be evolving to city life and rodenticide
- Identifying rat issues is easy, true IPM solutions are difficult
8:10 p.m., Vice President Rochelle Thomas thanked Matt for his talk and facilitated the Q&A portion of the program.
8:28 p.m. Vice President Thomas passed the floor back to President Chaya, who thanked Matt, as well, and invited attendees to return for next month’s program, “Birdsong for the Curious Naturalist,” by Donald Kroodsma.
8:29 pm – meeting was adjourned.
Respectfully submitted by Amy Simmons, Recording Secretary