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00:00:01] Stephen Vantassel here for living the wildlife on the talk today about deer mice because deer mice are a species of animal that are frequently ignored in the conversations about commensal rodents deer mice are more common than people give them credit for and they are rather ubiquitous. So I wondered who thought to give a synopsis of a really fine article by Dr. Gary W. Whitmer and Rachel S. Moulton. They wrote an article deer mice Peromyscus species biology damage and management. A review that was published in The 25th proceedings or I should say the proceedings of the 25th vertebrate pest conference published in 2012. And these were pages 2 13 through to 19 and what they did was a summarize the research up that they were aware of up to this particular point. So it was pretty pretty neat. They did it. So the reality is is that.
Deer Mice & Whitefooted Mice Are Far More Common Than People Think
[00:01:14] These animals are far more common as I noted than people realize and they’re often ignored in the training and I wanted to sort of fill that gap today so they’re both rodents of course and we want to talk about two different species one of them is called the deer mouse.
[00:01:32] Peromyscus maniculatus and then we also have the white footed mouse which is sometimes mistakenly called the white footed deer mouse that would be incorrect. It’s the white footed mouse that’s Peromyscus leucopus both of them have extensive ranges in the United States. The deer mouse has a broader range. But for our purposes today we’re going to combine them and treat them as a unit because they both share similar characteristics. I mean they’re not identical obviously but they’re for our purposes for pest control. They’re close enough and so on want to talk to them about some of their biology in this regard.
Deer Mice & Whitefooted Mice Biology
So I wanted to begin discussing some of their biology and we’re going to talk about how how big they are. And that sort of thing. So let’s get started with that. So deer mice grow vary in size according this particular article and they can be anywhere between 15 and 30 grams which is for our purposes half an ounce to a little more than downside weight their total length. Now whenever you read the literature that says total length they mean from the tip of the nose all the way to the tip of the tail it’s total length. If they talk about body length then it would just be the tip of the nose to the you know basically to their butt. It’s how they would measure the animals. This is total length and we’re looking at about 130 to 200 millimeters which would be five about five inches to little over seven and a half inches and I’m sort of you know rounding off those numbers there a little bit to make it more memorable.
[00:03:19] So you identify deer mice separate from house mice by looking at their eyes the deer mice eyes are bigger than the house mouse. These are nocturnal animals just like house mice but deer mice are spending their time of course outdoors typically although they can do pretty well in structures as well. And they also have larger ears than than house mice. And then they also have most characteristically a a sharp bifurcation between the stomach for which typically white and the back for called the door salary which is typically like deer like coloration or tarnish coloration where the house mouse the cut the change between the dorsal area of the back to the stomach tends to be much more gradual as it gradually changes in coloration for deer mice. It’s like someone just drew a sharp line like Drew. You know it’s like your coloring as a kid you’re coloring within the lines and so it goes brown to white instantly and the bi colored tail could be quite stark. So that’s how you’re gonna help help you quickly identify that you’re dealing with deer mice you can’t really do it on the basis of scat although some people think that you could you really need this sort of trap some and make sure that you are dealing with deer mice because the scat is going to be similar in size and you probably don’t have enough experience to be able to distinguish them in the field setting. And I think that be a lot of variability there. Now they have pretty high reproductive rate. [00:05:08] I mean it’s you know it’s certainly going to be similar to that of house mice.
Deer Mice & Whitefooted Mice Breeding
So they can have anywhere from one to nine pups as a female and typically for females in northern regions the they’re going to be mating primarily having pups between March and October in warmer climates. They could be mating year round. So you have to be sure you understand that there’s going to be a difference between the northern tier of the United States and the southern tier of the United States because deer mice can be found from the coastal areas to the Alpine areas to above the two two valleys to deserts to urban areas I used to live in Lincoln Nebraska I had deer mice in my house and I lived literally in the middle of the city. So we had deer mice there so don’t just assume if you’re in an urban area Lincoln was about two hundred seventy five thousand people that kind of give you an idea how big the city was. We were in the middle and we had deer. So don’t think that you’re only going to be dealing with house mice and urban areas it’s simply not simply not true. Deer mice like to live underground. They’re not great diggers but they do like living in areas below ground. They will also nest above ground as well so they they can climb and they typically lie in their nests with large quantities of plants shredded materials can be twigs roots grasses and they will also use feathers shredded shredded cloth the lines plied their delight their nests.
[00:06:54] So the females will have anywhere from three to four litters per year. And you could have generally for up to four generations produced in one year.
[00:07:09] If all of them achieved maximum survival again that’s very unusual in nature. So we’re talking about what the upper limit could be. You could have ten thousand young in one year because you’re going to have the young maturing and then having young and then they’re having young and then they’re having sex. But again that would be highly unusual of course. And I doubt we would ever be in a situation with that level of perfection. But that kind of gives you an idea of what they could do if everything was perfect and ideal and you didn’t have you know predation and disease mortality.
[00:07:48] But it’s an interesting number to know. They will share ness with each other so they have been researchers have found that 13 mice can be found huddled together. Females though that are an asterisk that means they’re ready to mate will get a little bit more belligerent and fight for their territory. So they will probably because they’re getting ready to mate and have young and so they get a little bit more antsy.
Deer Mice & Whitefooted Mice Habitat
How large is their home range. In other words we we know that house mice were looking at you know 30 feet typically of their home range probably look it could be a harder but deer mice are going to have a larger home range because again this is a native species of the United States with the house mouse isn’t. So the deer mice can live out in the wild with no problem whatsoever. They can also live with humans without much difficulty either. So how large of their home range. Well of course it depends on how much available food there is. And that can be anything from a tenth of a hectare now a hectare is two point two acres so to give you an idea of how large of an area that could be big what we would call a quarter of an acre in their home range could be as big as one hectare which would be about two point two acres. So how far do they travel. Well some research that was done in Nebraska actually found that they can travel about 100 100 meters which would be about almost a hundred and ten yards. So significantly larger mobility than what would be typical of house Miles. And that was a sugar beet field. If you’re looking for what their habitat was when that study was being done.
Deer Mice & Whitefooted Mice Feeding Behaviors
[00:09:37] When we’re also looking here at how they operate in terms of their diet they are omnivores so they will eat a broad array of food sources that could be everything from nuts and berries and fruits to insects carrion. It’s a deadly animal material fungi. Bones though not on bones of course eggs various plants and their seeds.
[00:10:07] And so the what they really love however is they love seeds so they will cash but their cashing hasn’t really been known to really help plant production per say so. But they do cash seeds and some of the seeds that they cash are those of the ragweed plant the Panic grass sorrel tick truffle oil apple cherry Douglas fir and acorns from an oak tree. So they have a little bit of diversity there.
Deer Mice & Whitefooted Mice Damage
What kind of damage can they do. Well they can. They can certainly hinder reproduction work that’s been done in forests. They can certainly cause impacts and seed regeneration which makes sense because they’re actually eating seeds or they’re eating the seeds then the tree can go grow obviously.
[00:11:03] They could also do some other day and I believe I had a nest of deer mice in my house when I was back in Lincoln where they actually just climbed a pole because a vine was using it and then they basically put a nest in the corner of my of my attic. It was a pretty large nest. It was filled.
[00:11:26] Probably one of that you know one of those trash can bags that you would use in your office for instance they would fill those holes quite it was quite large in that agricultural crops can also be impacted of course deer mice have been causing damage to almond orchards.
Deer Mice & Whitefooted Mice Control
And so what you need to understand about this is that when you’re trying to poison them if you’re trying to control this particular species you got to make sure that of course deer mice are on the pesticide label but also realize if you’re in the situation where there’s a lot of favored foods they’re going to be eating their favorite foods and not your bait.
So if you think you’re going to poison your way necessarily to success in difficult accounts that you’re going to you have something else coming for you. You really need to be thinking more substantively substantively about habitat modification which is removal of food sources hardening that structure by doing exclusion which I think something is which is something that many pest control operators, unfortunately, are not doing for their clients even simple jobs which I just. Which I think it’s terrible. I think that it’s not that much money that should be done. And you also want to be thinking of traps as well. We do know that deer mice will predate on birds and they will do some damage, of course, they’re on eggs and even predate on nest legs which gives kind of troubling.
[00:13:01] You may go online and actually see that even house mice have done this in certain island communities where they’ve put up trail cameras and watched certain bird nests and watched house mice attack those got those sadness links can be quite disturbing.
[00:13:18] But for our purposes what we’re mostly concerned about of course is how deer mice are entering into structures and of course they want like any small rodent they want to go to a place where it’s warm and what better place than a building they will eat the bird seed they will eat the pet food. So it’s important to keep those things stored properly.
Deer Mice & Whitefooted Mice Key Diseases
What is also important to understand is that deer mice are associated with two key diseases and that is the hantavirus of course as well. And also Lyme disease. So they are part of the Lyme Disease cycle.
[00:13:54] So as a structural pest control or wildlife control operator it’s critical that you whenever you’re in an area where you’re seeing a lot of droppings you know that there’s going to be you’re in there as well that you can’t see and if you’re stirring all that up you could be inhaling hantavirus into your lungs and come down with that particular infection. Thankfully it’s not a common infection. However if you get it there is a 30 to 40 percent mortality. So I’m not going to talk about how to protect yourself per say hantavirus at this point but I am going to encourage you to go to this CDC that’s centers for.
[00:14:36] Disease Control and read the information about what to do about hantavirus. Now Lyme disease of course. What you want to be concerned for there is the ticks. So where you have deer mice can also have ticks. So you want to be thinking about you know you’re walking around tall grass. You wanna make sure you’re doing tick checks. You want to make sure you’re looking at how you’re removing those ticks. The CDC will have additional information on that as well. So again we never want to hype the fear on disease especially with our clients. We don’t want to create that kind of a crisis. However you as the professional need to be sure that you are understanding how you protect yourself. And so you’re going to be wearing your HEPA filter. You should be wearing your Tyvek suit and you’re going to crawl spaces whenever you’re going into enclosed areas you should be wearing that respirator properly fitted. If you’ve got a beard the beards got to go unless yours Phil lets your mask is able to seal against the skin in such a manner that you don’t have to worry about that SEAL problem.
[00:15:47] So learn to protect yourself. Thankfully bleach 10 percent bleach solution kills the hantavirus. And of course time will kill the hantavirus. So this is one infection that will go away over time. Where is this going to be most important for people to to be aware of and that is areas that are undisturbed for long periods of time. So I’m in Montana and we have a surprisingly high amount of hantavirus infections for the size and population of our state we only have one point two million people in the entire state.
[00:16:21] So why would that be. Well because a lot of people have cabins in our state that’s absolutely gorgeous and they use that they have it. They leave it empty in the wintertime Of course the rodents love being there we have deer mice across the entire length of the state. So an owner comes back in the spring opens up the building and they realize you know there’s droppings over droppings on the floor perhaps and maybe they’re sweeping instead of mopping and then they can expose themselves to that active virus and then they come down with this illness and it’s quite serious. One can only imagine how many infections occur where people recover and they don’t never bother I think they have the flu or something.
So be careful. We don’t want to hype it because it’s something you can easily protect yourself with. So how do we control this particular animal. Well you control it just like mice. So you want to do your habitat modification. You want to do your exclusion the building you want to control the food availability. You want to set traps and the course you want to be able to use your toxins. You want to take that multiple approach multifaceted approach to controlling the species then you can get good success. So what kind of baits can you use if you’re using baits. Well you can use them simply use peanut butter of course make sure you’re watching out for peanut butter allergies for your clients.
[00:17:42] Don’t pull out the Skippy jar. Make sure you repackage your peanut butter. I recommend putting it into a different color. Putting it into a putting green coloration into it so people don’t know it may suspect what it is. Oh it might be peanut butter in there yep there could be. But you want to make it look different than skip than your Skippy peanut butter repackage it so you don’t pull out of Skippy jar. It’s just not professional and it’s insulting to your clients. Sunflower seeds of course are always a big hit. Make sure when you’re using traps with seeds make sure they’re not visible to birds because birds will be attracted and then you end up killing birds. Your regular snap traps are going to work fine for your deer mice just again. Make sure you’re wearing you’re wearing your gloves your being your avoiding contact with the urine and feces because that could be infected with the hantavirus there. So make sure you read that literature at the CDC to learn how to handle that again. You can also use toxic pens just be sure that you are paying attention to the label to make sure that deer mice are listed on the label. I would encourage people to be thinking about first generation anticoagulants before you turn to second generation anticoagulants.
[00:19:03] So that would be your warfarin Chlorophacinone Diphacinone because you couldn’t have a lower impact on non target species in secondary poisoning of course if you want to really reduce that risk you can use things like zinc phosphide which of course is of extraordinarily high initial toxicity but the secondary poisoning is extraordinarily low.
There seems to be some indication that Cholecalciferol has a very low secondary poisoning. rate I’d have to do a little bit more reading on that. I’m not really convinced with some of the literature that I’ve been looking at presently but it seems like it’s a lower risk. And so I can certainly say that but I’m not sure. Cholecalciferol is labeled for deer mice now. So make sure you check your label but treated like deer my like your house mouse.
Except understand that their home range is going to be significantly higher and you have that significant disease issue that you don’t have to the same extent as you do with house mice. The House mice certainly have their own diseases but the key for you and your client is that hantavirus to be careful. Well I hope this has been helped for you. This Stephen Vanassel for wildlife control consultant. Back to you Frank.