Can An Early Spring Confuse Nature's Clock?

It's been an unusually warm winter in some parts of the country, with springtime temperatures and very little snow. How is nature responding? Purdue entomologist Tom Turpin and horticulturalist Kristin Schleiter of the New York Botanical Garden discuss how an early spring affects flower buds, beetles and bees.

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IRA FLATOW, HOST:

You're listening to SCIENCE FRIDAY. I'm Ira Flatow. It's been a pretty warm winter out here in the east, hasn't it? Well, actually all over the country. And, you know, it turns out all the lower 48, January was the third-least snowy on record, the fourth-warmest winter on record. Only New Mexico had a colder winter than record, and all four of these have been within the last 20 years.

And I'm not complaining because springtime temperatures are OK with me. I get out in the garden. But, you know, when you go out there, what do you see? You see the early spring buds. They're bursting, the leaves are growing. I was out pruning my rose bush already. Bees are buzzing, the squirrels are out, and if the climate change is running its course, is this sort of the new normal for us?

What do you think? Our number, 1-800-989-8255, is here. Let's talk about what you're seeing that's happening in your neighborhood about early signs of an early spring. And we're going to talk about why that may not be such a good thing that spring is happening so quickly because what is happening to the flowers and the animals and the bees?

We're going to talk about it with my guest. Kristin Schleiter is acting director of outdoor gardens at the New York Botanical Garden in The Bronx, one of New York's jewels in The Bronx here. She joins us here in our New York studios. Welcome to SCIENCE FRIDAY.

KRISTIN SCHLEITER: Happy to be here.

FLATOW: Thank you, Dr. Schleiter. Tom Turpin is professor of entomology at Purdue University in West Lafayette. He joins us from the studios of WBAA in West Lafayette. Welcome back to SCIENCE FRIDAY, Dr. Turpin.

TOM TURPIN: Well, good afternoon. It's my pleasure to be with you.

FLATOW: Now are you seeing an early winter out there? An early spring I meant, an early spring.

TURPIN: We are seeing an early spring. It's been one of the milder winters that I can remember, and that's getting to be a number of years now.

FLATOW: Yeah, Dr. Schleiter, what's going on in the garden now? Have you seen signs of things happening early?

SCHLEITER: Sure, we have all sorts of things happening early, a lot of trees that usually would only have - would be beginning to bloom right now, they're already done with their blooms, so we're...

FLATOW: They're done?

SCHLEITER: Yeah, we're early.

FLATOW: And we were talking about that the - the U.S. Department of Agriculture, that keeps track of the growing seasons in different parts - if you're a gardener, you know that there are different parts of the growing season, the zones there, they've changed the zones, right?

SCHLEITER: Yes, yes. Here in New York and along the coast here, instead of being sort of the warmer six zone, we're now the cooler seven. So we're getting warmer.

FLATOW: Wow, Tom, has your zone changed at all?

TURPIN: We have changed our zone here in Indiana, as well. But Kristin may tell me differently, but I'm not going to plant any of those plants for a little while yet to find out how true this may be.

SCHLEITER: Well, we've been planting a lot of those plants already to see if we could sneak them through.

(SOUNDBITE OF LAUGHTER)

SCHLEITER: So now...

FLATOW: What plants? What plants are you talking about?

SCHLEITER: Oh, things like Japanese apricots, prunus mume, or mahonia, Oregon grape hollies, edgeworthia - the paper bush - we've gotten to come through. We have one garden called The Lady's Border, where we really try to push the zonal plants, and that's where we've got most of those plants to come through, really beautifully, for 10 years already.

FLATOW: Wow, wow. But Tom, there is a downside to this with insects, is there not, that the - that we - go ahead.

TURPIN: Yeah, I was going to say a downside in that you think we're going to have more insects as a result of the warmer winters?

FLATOW: Yes, I mean, aren't we going t get more pests coming out earlier or...?

TURPIN: Well, I don't want to shoot this balloon down here, Ira, too much, but the truth of the matter is that warm winters generally would result in, maybe more species of insects. But if you talk about individual pest species, you almost have to talk about them individually because some actually are helped by a warm winter while others are harmed by a warm winter.

So I don't think we can generalize as far as the insects are concerned.

FLATOW: Good. Well, give us specifics, then, about which are helped and which are harmed.

TURPIN: Well, take for example a insect that has become kind of a pest insect, the Asian ladybug. Now, it's beneficial to many of our growers, our gardeners, because it feeds on aphids. This insect over-winters as an adult, it over-winters in sheltered places, and basically when we have warm winter days, it breaks itself out of hibernation, goes searching for aphids, and I think Kristin would agree, there are very few aphids on our plants out in the middle of the winter, so there's no food for it.

So it's using up its stored food resources in its own body, meaning that it may in fact not even survive 'til the springtime when it should begin to lay eggs. So there we have an insect that would be actually harmed by a warm winter.

Another example might be the honeybees. Honeybees are social insects, and they then spend the winter as a group, a colony. During the winter, they're out flying around looking for pollen and nectar, and Kristin's plants are not providing any of that in January and February here in Indiana, for the most part. So they're using up their colony supplies.

The clusters in the colony then may not form as tightly, and so the egg-laying and the brood formation maybe doesn't do as well, and we might see that that colony is going to be impacted by a warm winter.

FLATOW: Kristin?

SCHLEITER: Well, I have to say we did have an awful lot of honeybees that appeared the very minute some of the plants opened. So definitely they were active because it was warm and looking for food. So I guess we have some lucky honeybees at the garden because they were well-fed. They've been well-fed through February.

FLATOW: Isn't there - is there some risk that this is false period of - we may get a big cold snap that comes in, below-freezing temperatures, and might kill off some plants or insects that might not survive?

SCHLEITER: Certainly from the plant point of view, we could lose bloom, certainly. A lot of the buds are beyond the point of no return at this point. But the trees or the perennials probably wouldn't be damaged for the long term. You just wouldn't have your flowers this year, especially if it's a once-blooming plant.

FLATOW: And what about fruit, you know, that are setting their flowers?

SCHLEITER: Absolutely. If you lose, for instance, apricots, very early blooming, if you lose your apricot flowers, then you have no fruit for the season.

FLATOW: Tom, you agree?

TURPIN: Well, actually I think it's true that the insects are going to be out earlier, and I agree with Kristin when she's saying that the honeybees would be out there. But our honeybees would fly on a day above 50 degrees, as they would in New York, whether or not there are any blooming flowers out there or not.

They - if the flowers are blooming, the honeybees will be there. What I'm saying basically is that if there are not flowers blooming, and there aren't pollen and honey, then they aren't being beneficial to their colony when they're out there. So ultimately, if we have too many warm days before the flowers are out, that will be harmful to the bees.

FLATOW: Well, that's sort of a mismatch. Could there also be a mismatch between when the pollinating insects come out and when the flowers are out, and you're not going to get as much fruit this year because the insects won't be out when the flowers are gone.

SCHLEITER: Certainly...

TURPIN: Oh, I - go ahead, Kristin.

SCHLEITER: Certainly, no, that certainly could be. If the pollinators aren't there, then you're not going to have the fruit.

TURPIN: And from an entomologists' point of view, I think I would have to point out that in general, the solitary pollinators - we're not talking about the honeybees but those solitary bees that are primary pollinators in most of our gardens - are probably keyed into the same factors as the plants are. So if we have an early emergence of those plants, I think you can probably imagine there's an early emergence of those pollinators, as well.

Those two items, plants and the insects, have co-evolved for literally millions of years and probably are keying in on the same environmental factors. So I think the bees, the pollinators would be out there if those plants are in fact blooming.

FLATOW: 1-800-989-8255. Denise(ph) in Toledo, hi, Denise.

DENISE: Hi.

FLATOW: Hi there.

DENISE: Thanks for taking my call. You guys were asking about some of the odd things that we've seen. I love mustard greens, and I'm from Louisiana. But I planted some last summer, and I still have the - they've grown throughout the entire winter this year.

FLATOW: Wow. And they're still producing?

DENISE: They're still producing. So I may not have to replace them.

FLATOW: I imagine there are other - I wonder, you know, if sort of like broccoli made it through the winter, that sort of thing.

SCHLEITER: I would imagine a lot of those cold crops, broccoli or kale, even spinach maybe, might have just made it really well through this cool temperature without big snow cover to squish the leaves down into the soil.

FLATOW: Well, are you seeing anything else, Denise, growing there that...

DENISE: You know, just some violas, and I have some other just random plants that have made it through. But I was just really shocked about the greens because usually they're gone, you know, by early December, so...

FLATOW: Yeah, thanks for calling. 1-800-989-8255 is our number, and does this mean we should go plant things earlier, or we should just wait? Because it seems here, and I know they moved the zones, it seems like we have a two-week difference. That's how I just it. It looks now like things are moving two weeks ahead than they used to be.

SCHLEITER: Yeah, I think this winter specifically is a fluke and not really - you can't assume global warming because of one fluky, very, very early winter. But the fact that the USDA has moved us a zone warmer, that's showing longer-term data that they're tracking. And that is real indication that we are becoming warmer.

FLATOW: Mm-hmm. Tom, are you seeing any insects moving around, let's say, going further north because it's warmer?

TURPIN: Exactly. I would sort of echo what Kristin's saying about this. We are seeing insects that normally don't overwinter as far north as parts of Indiana, coming out early in the springtime, suggesting they have overwintered here. What that really indicates is that there are species of insects that aren't really adapted to these winters, and now they're encountering conditions which are allowing them to survive. So I think the movement of the insects further north is as good an indication as the ability of those plants to survive further north, as well.

FLATOW: Mm-hmm. 1-800-989-8255. Tell us about skunk cabbage. This was really interesting. Now, doing our research, you were telling us, Dr. Schleiter, about the unusual temperature, the ability of a plant to raise the temperature of its self.

SCHLEITER: It's really interesting. I was actually just doing some research on this. There's a biologist named Roger Knutson who discovered that skunk cabbage, in fact, raises its own temperature up to the point where it's an average of 36 degrees above the ambient air temperature for two weeks in the spring to help - well, and, you know, I'm assuming that it's bringing in the bugs for pollination. It's also - with the heat, it's creating wonderful air circulation in there, spreading its scent further to draw pollinators in. It's just incredibly interesting.

FLATOW: Could it be actually melting a hole through snow that might be there?

SCHLEITER: Absolutely. Yes. It apparently feels warm. If you touch it, it will feel hot.

(SOUNDBITE OF LAUGHTER)

TURPIN: OK, Ira.

FLATOW: You know about that, Tom?

TURPIN: Well, no. I want to find out about this. That's the reason I love SCIENCE FRIDAY, is I learn all kinds of things, you know?

(SOUNDBITE OF LAUGHTER)

TURPIN: But insects sort of do the same thing. The honeybees cluster, and the...

FLATOW: Right.

TURPIN: ...heat of metabolism then raises the temperature in the inside of that cluster up to above 100 degrees Fahrenheit for the incubation of the eggs. Moths will, through muscle contraction, if they're below 50 degrees Fahrenheit, will raise the temperature up to where they can fly. And that's the reason you'll see a moth flying around on a day when the temperature is maybe just about 50 degrees or so. So there we understand that, because that's metabolism in an animal's body. But tell me about that skunk cabbage. How is it raising its temperature?

SCHLEITER: Apparently, it has large starch stores in its root system, and it's burning it just, you know - they say it uses up oxygen, about as much oxygen as a small mammal in those couple of weeks.

FLATOW: No kidding.

SCHLEITER: Yeah. It's amazing.

FLATOW: 1-800-989-8255 is our number, talking about skunk cabbage and everything else that has to do with spring this hour on SCIENCE FRIDAY, from NPR. Talking with Kristin Schleiter and Tom Turpin. And let's see if we can - because people are very much eager to talk to us. Let's go to Mandy in Arkansas. Hi, Mandy.

MANDY: Hi. How are you?

FLATOW: Hi, there. How are you?

MANDY: Doing all right. We are busy in our garden right now. We've gone ahead and just tossed out our USDA map, and we're going with planting everything because it's growing. Our - we have beehives, and our bees are very active right now. They were pollinating our peach trees. But one of the interesting things that we're already seeing - and you can hear all the locals complaining about it - is we already got mosquitoes.

FLATOW: Wow.

MANDY: So we're dealing with pests already that we usually only see when it's a lot warmer.

FLATOW: Comments about that?

TURPIN: Well, I think Mandy wants it both ways. I mean, the bottom line here is that if those bees are going to be out and be active, then those mosquitoes are, as well. And here we have a couple of insects that obviously are responding to the increased temperatures by earlier life cycles and things, and it's not surprising. They all respond to the same kind of environmental clues.

FLATOW: Mm-hmm. All right. Thanks. And good luck on your garden, Mandy. Thanks for...

MANDY: Thank you so much. You, too.

FLATOW: Thanks for - you, too. Let's go to - stay on the phone to Shane in Virginia. Hi, Shane.

SHANE: Hey, how's it going?

FLATOW: Hey, there.

SHANE: I don't know if either of your guests will be able to help me out on this, but I figured I'd give it a shot. Last year, I went out hunting for morel mushrooms. And I ended up talking to my mom about it, and it turned out I was - I went about two or three weeks too late. Well, with the weather being - like you mentioned earlier, it's kind of like everything is two weeks ahead of schedule. I wanted to know if either of your guests or you yourself or if any other listener might have some advice on - I know, in Virginia, typically your morel time is towards the end of April, to the very first week of May. Generally, like, Mother's Day is always the cutoff, and you're pretty much done by then. So I wanted to know if maybe I should go, like, the first and second week of April, rather than towards the end of April, since the weather is so much warmer than normal.

FLATOW: Yeah. You should have called on a fungus expert.

(SOUNDBITE OF LAUGHTER)

TURPIN: Exactly. You've got a botanist and entomologist here. But I'll tell you what. This old bug guy from Indiana is also a morel hunter, and I go out on my own woods and look for them. I'm not going out on a calendar date anymore at all. I use some of the phenological indicators, the plants out there, and they've been out a little bit earlier the last year or two, and I found the first morels a couple of weeks earlier than I have. So I would agree with that observation.

FLATOW: Thanks for calling, Shane. In the minute we have left, Kristin, what's going on in the garden? What's going on out there to come out and see that's blooming?

SCHLEITER: Well, outside, we've got daffodils by the score. We've got - the winter hazels are starting. The first magnolia - I saw a magnolia stiletto in full bloom.

FLATOW: No kidding.

SCHLEITER: I know. But inside the conservatory, we have our orchid show on right now, which is really extraordinary and just a wonderful place to sit and be cozy and look at a beautiful display.

FLATOW: Tom, you've got something you'd like to tell us about?

TURPIN: Well, I was going to say that I think Kristin's cheating. She's got the inside kind of a thing. I - and we can go into our bug barn and watch all kinds of insects being active there, as well. But the truth is, I think we have seen a lot more activity this year of early-season insect activity, including, I've got to admit, that I was bitten by a mosquito at the end of February in my bedroom this year. And I am not liking that at all.

FLATOW: Wow. There you have it. Can't get better, you know, first-person reporting than that.

(SOUNDBITE OF LAUGHTER)

FLATOW: Thank you very much, Tom. Tom Turpin is a professor of entomology at Purdue University in West Lafayette, Indiana. And Kristin Schleiter is acting director of outdoor gardens at the New York Botanical Garden in the Bronx. Thank you.

SCHLEITER: Thank you.

FLATOW: Thank you both for taking time to be with us today.

TURPIN: Thank you.

FLATOW: We're going to take a break, and when we come back, we're going to talk about Pluto, the planet - well, not the planet, the, sort of - well, it depends on who you ask. We'll talk about Pluto and a mission to Pluto and the actual - there's a push, actually, to get a new stamp for Pluto and the mission to the body of - we'll talk about it when we get back. Stay with us. I'm Ira Flatow. This is SCIENCE FRIDAY, from NPR.

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