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Brian Lehrer: Brian Lehrer on WNYC. We will close the show today with our climate segment of the week, which we do every Tuesday. In this case, your call is to help us report this climate story on an unlikely sign, perhaps, of climate change more deer. In the past decade, the deer population in New York has exploded. According to a USA Today analysis, hunters killed almost 232,000 deer in 2022 alone, a 10% increase from the year before.

Back in the 1950s when they began tracking this data and when hunting was much more popular, an average of just 57,000 deer were hunted every year. Milder winters are helping deer, that's the top line. The deer ticks that carry Lyme disease survive. Beyond the hunting numbers, there is a human toll emerging.

A new article in Lohud serving Westchester and Rockland, breaks it down like this. "More than 70,000 New Yorkers suffer injuries or financial hardships after their vehicles hit deer on roads each year. Another 7,000 residents fall seriously ill each year with debilitating symptoms of Lyme disease caused by the ticks that survive on the deer." New York Farmers report their deer-related crop damage losses to be about $59 million a year now, a lot more than in the past.

Joining us now to break down the link between climate change, deer, and how these populations can be managed to reduce car accidents and Lyme disease and crop damage is Toni Lyn Morelli, research ecologist at the Northeast Climate Adaptation Science Center, an adjunct associate professor in the Department of Environmental Conservation at the University of Massachusetts. Dr. Morelli, welcome to WNYC.

Toni Lyn Morelli: Thanks so much for having me, and I'm honored to follow that segment with George Tekai.

Brian Lehrer: Really, he was great. Listeners, help us report this story. Have you experienced more problems with deer in the past few years because of climate change? 212-433 WNYC or our guests will relate it to the climate change. You don't have to know the science. Just tell us if you're noticing more deer, what sorts of problems they have caused if they're causing problems. Are more of your friends and family getting diagnosed with Lyme disease? What's that been like? Have any of you started hunting deer?

What can you report from the battlefront of population control? If you look at hunting that way, 212-433 WNYC, 212-433-9692, or you can text as well. Dr. Morelli, a lot of people downstate, or at least in the five boroughs, will know we haven't seen substantial snow in a long time, but just how mild our winters getting in the Northeast in a way that pertains to deer.

Toni Lyn Morelli: We really just had this year without a winter. The US had its warmest winter on record this past year. It was 7 degrees warmer on average than it was last century, 7 degrees Fahrenheit. That's real numbers. We're seeing this broadly. Some are calling it the warming winter syndrome. It's the seasons that's being most affected by climate change. We have seen later starts to winter, and then it ends earlier, less snow for most of the Northeast. Like you said, very little snow, if any, for downstate areas. This is having negative impacts on our natural ecosystems around the areas, forests are under threat.

Trees aren't handling this well, but there are some species that are happy to see these mild winter conditions, and that includes white-tailed deer.

Brian Lehrer: I read that stat at the beginning that 7,000 New Yorkers report getting Lyme disease each year up from numbers in the past. For people who maybe aren't familiar, can you just explain what Lyme disease is and how it relates to deer, because it's also seasonal, right?

Toni Lyn Morelli: Yes. That's interesting. Lyme disease has a complicated life history. It's a virus carried in bacteria carried in mammals. We have interactions with these mammals like deer, mice that can be carriers of this bacterium and accidentally coast the tick that then passes it to us. We're an accidental interaction with that tick. That doesn't mean to give it to us, but if we're outside and happen to get the critters on us, then we can get the problem. That can be really debilitating immune impacts for a long period of time. The interaction it has with climate change is that some of the species that act as carriers for the tick are seeing increases in population with warming winters.

With deer increasing in abundance, again because of milder winters, as well as changes in the landscape and ways in which deer are supported, having more food and fewer predators, then we end up with higher tick populations and ultimately more Lyme disease.

Brian Lehrer: Would it be accurate to say that the ticks die out when the temperature is below freezing? We are in tick season already by now?

Toni Lyn Morelli: Yes, exactly. The general rule is over 40 degrees, that's when deer ticks are active, deer ticks that cause Lyme disease. That's a general rule. It's not strict, but we're seeing fewer and fewer days that are colder, that are below freezing or even below 40 degrees. Ticks are becoming more abundant as they're able to survive over winter more without having these very cold days. Then they're out longer in the year as well.

Brian Lehrer: Roland in Albany, you're on WNYC. Hello, Roland.

Roland: Good morning. How are you doing? Thanks for this segment. I live in Manhattan, but I have a property in the Albany Yard in Columbia County where I raise corn as a hobby, other vegetables too. It's almost as if the deer know that I only come on weekends because from Monday to Thursday they help themselves with my corn. They don't just eat like one here, they take a bite here, a bite there, a bite here, a bite there so that they can ruin the whole [unintelligible 00:07:33] of corn without-- If they would only take one here, I'd put it out for them, but it doesn't work that way, at least with my deer anyway.

I think a large part of the problem is not just-- the warm weather has made a change. I've had this place for 30 years. I've been hunting for 30 years on my property. The disappearance and extinction of the Eastern timber wolf was a large part of another reason why we have the expanded deer population. The deer would much rather eat my corn than anything, but the timber wolf like to eat deer. I've been calling Encon, New York State Environmental Conservation for the past several years saying that either hunting or driving or going for a walk after dinner I've seen animals that I thought were wolves. They keep telling me that I keep seeing coyotes or dogs.

I saw this past hunting season. I was pretty distinct. I can tell a deer from a coyote, that it was not a coyote. I just learned that Encon just issued a new procedure where any coyote kill is going to be autopsied now in DNA to determine whether or not it really is a wolf.

Brian Lehrer: Roland, I'm going to leave it there for time, but very interesting anecdote about the increasing deer population up in Columbia County. Dr. Morelli, population control can come in many forms, but it's tricky and heavily populated urban and suburban areas. Not really like where Roland is, but closer to the bigger cities like that article in Lohud notes that deer are being sterilized on Staten Island. In Westchester, you're only allowed to hunt with bows, not guns. I didn't know that. Can you talk to us a bit more about population control measures if the warming is leading to a proliferation of deer that are causing problems?

Toni Lyn Morelli: Yes. I really appreciate Roland's perspective. I talk to a lot of farmers who are endlessly frustrated with figuring out how to manage the deer in there that affect their livelihoods. I think he's really made a great point in thinking about the predators that are on the landscape, the ones that used to be and may be be welcome again. Coyotes are pretty happy right now in terms of the intersection of human and rural landscapes even in the middle of New York City and with climate change. If we have coyotes out there, they can potentially be creating what we call landscape of fear. Even if they're not actually taking out a lot of deer, they're making sure the deer moving along and watching around and not sitting and eating, or sitting in the roads, ways that they really have negative effects on us.

Yes, there's a lot of important conversation to be had around hunting, and the regulations around hunting, and new generations of hunters, and whether people want to see venison at their local farmer's markets, and ways in which culture of deer hunting could be created that could potentially be one management strategy in the face of what is both an ecological environmental and economic concern for all of us.

Brian Lehrer: How about this pushback as we start to run out of time? A listener writes, "I appreciate your climate story of the week, but it's disturbing that this week's segment views the deer as objects that cause problems for us. This anthropocentric view is a large part of how we got into the climate catastrophe."

Toni Lyn Morelli: Yes. Thank you for sharing that, and thank you for the person who wrote in. My job is to work with resource managers, and their job is to think about how to do restoration on the land and to think about nature and how to help species living together and being productive. White-tailed deer is the species they tell me over and over again, is basically their biggest problem in getting in the way of them trying to make sure we have healthy ecosystems. This isn't just about how they affect humans. It's also the impact they're having on forest communities and other species.

Brian Lehrer: We have other callers and texters who we're not going to have time to take who are giving us stories of impacts on wildflowers, impacts on other things as well. Just to put a pin in it, we just got 15 seconds, but deer are pretty hard to count in general. How do we know that the deer populations are increasing? Is it all just anecdotal?

Toni Lyn Morelli: No. Absolutely not. We have great data on this. It is a tricky like everything. Ecology is tricky, but we have harvest data that are required from hunters to turn in. We have aerial surveys, we have camera trap surveys. Recent research showed that the population of deer basically doubled in Pennsylvania over the last 30, 35 years. No, we have real numbers on this that show that it's not just that they're interacting with us more, there's actually just many more of them out there.

Brian Lehrer: Dr. Toni Lyn Morelli is a research ecologist at the Northeast Climate Adaptation Science Center and adjunct associate professor in the Department of Environmental Conservation at the University of Massachusetts. That's our climate story of the week. Dr. Morelli, thank you so much.

Toni Lyn Morelli: Thank you very much.

Brian Lehrer: Brian Lehrer on WNYC. Thanks as always for listening. Stay tuned for all of it.

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