Rise of the Machine

I’m a big SciFi fan.  The Alien and Terminator series are two of my favorites.  I’ve seen Aliens so many times that I can recite any scene.  Try me.

Aliens was released in 1986.  Terminator 2: Judgement Day (my personal fav) was released in 1991.  Teenage me didn’t think much about the reality of Ash, Bishop, or the Terminator himself.  These androids, synthetic humans, and autonomous killer robots were just characters on the screen.  Teenager or not, I knew the difference between fact and fiction.

Fast forward 30 years.  Siri is on my phone and Alexa could be on my kitchen counter (but she’s not.  I’ve seen 2001: A Space Odyssey too!)

Talk of artificial intelligence (AI) and machine learning (ML) is not just the stuff of SciFi movies anymore.  It has become mainstream.  From aviation to healthcare to music, the applications of AI in today’s world abound.  

Wildlife research has had a loving and intimate relationship with technology for decades. It was just a matter of time before the wildlife department and the computer science department started talking to one another.  

We use GPS collars that talk to satellites.  VITs that email us when a fawn is born.  Trail cameras that can send pictures straight to our smartphones.  But none of that stuff works without us in the drivers seat…until now.  

Years from now we can say it all started with trail cameras.  Trail cameras are an incredible tool for wildlife research.  The ability to remotely observe critters is game changing. If those camera traps do what they do best, a researcher can end up with 1,000s of images.  Our own camera traps captured over 200,000 images.  Some studies have resulted in millions.  YAY DATA!   

Then you realize someone needs to look at every one of those photos and identify what’s in them…yay data…:( 

I mean if Siri can tell me where the closest coffee shop is then surely she can help look at some pictures.  Right?

Actually, yes.  Some super-smart people at the University of Wyoming just published a paper detailing machine learning models that accurately classify 2,000 images per minute on a laptop similar to the one I am using right now.  Even more exciting is that they have made this software package available to any user of Program R, a widely used programming language and free software environment for statistical computing.

Training “machine learning models using convolutional neural networks” to recognize elk and mule deer is the bomb.  Amiright?  Seriously, I have no idea what that means.  And while this is surely going to transform how quickly we can analysis and assimilate data, it is still a bit creepy.  

It’s just a matter of time before we ask one of these convolutional neural networks to ID a bobcat and it says “I’m sorry, Dave, I’m afraid I can’t do that.”  

-Jeannine Fleegle
Wildlife Biologist

PGC Deer and Elk Section

 

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Out with the old

Well, here I am again.  Getting ready to give more attention to the most worshipped part of the whitetail anatomy.  I managed to avoid it for a couple of years.  It was a good run.

I have chronicled my love/hate relationship with antlers; shared my passion to hunt for them; and defended those creatures that do their best to produce them on this blog in the past.  Ah antlers – will the conversation ever end?  

Of course not.  These are antlers.  A marvel of evolution.  A standard by which to judge.  A religion to some. 

So what’s the latest hubbub on the antler front?  Bucks without them…during deer season.  Gasp!

This year I have answered more questions than normal about what seems like more bucks than normal without antlers.  The story often goes something like this:  I shot a buck and when I got to him, one of his antlers had fallen off.  Or I was dragging my buck out of the woods and his antler popped off.  

This often surprises the happy and successful hunter and starts a myriad of theories as to why this might be.  

Bucks were rutting so hard that their testosterone levels were low causing them to drop their antlers or maybe bucks shed their antlers once all does are bred. 

Interesting.  They sound plausible.

Every year more than 30 deer aging teams descend upon hundreds of deer processors to gather data on the annual deer harvest.  Deer aging teams look at 25,000+ deer heads every year harvested during the 2-week firearms season.  

My team ages about 900 deer heads a year and I’ve been doing this for 15 years.  Some quick math will tell you that I have seen over 13,000 deer heads to date.  Fun Fact: a 50-gallon drum can hold about 40 deer heads!  

After the first hundred or so, I don’t pay much attention to the heads as I’m cutting and slinging.  A deer head is a deer head.  I call out sex and age to my data recorder and pitch it.  My goal is to get these data as efficiently as possible then get dirty, smelly, sometimes soupy heads off my board as quickly as possible.  Did I mention it’s cold during deer season?  And the sun NEVER shines when I age deer?  But I digress.

When I come across an antlerless deer that is male and NOT 6-months old, I don’t even pause.  I age shed antler bucks every year.  All aging teams do.   

With the spike in questions regarding shed antler bucks during the firearms season, I decided to look back over the data to see if there was spike in the number of shed antler bucks we aged.  I didn’t notice anything out of the ordinary but memory, as we all know, can be deceiving.  

From 2012-2017, the number of shed antler bucks aged by aging teams waffled between 3% and 4%.  

What was it for 2018?  4%!  

Nothing out of the ordinary.  But I age deer every year and I see shed antler bucks during firearms season every year.  

The average Pennsylvania hunter has been hunting for 40-ish years.  If he or she was successful in harvesting a buck every year (which is not the case), a hunter has seen less than 1% of the deer heads I have.  If one of those bucks pops an antler the first week of December, it is rather alarming.

The standard answer I give when asked about a buck that has lost his prize possession during the firearms season is natural variation and general health (which relates to nutrition) of a buck contribute to the timing of antler drop which occurs any time from December through March.   

This year was no different from years past.  Regardless, it’s time to cast off what’s been weighing you down and start anew.   The new year will bring a clean slate and, for deer, another set of fancy head gear.

-Jeannine Fleegle
Wildlife Biologist
PGC Deer and Elk Section
 

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Ungulates who wander

Pennsylvania whitetails, like the state’s human residents, are homebodies.  Fun fact: 74% of Pennsylvania residents were born in state.  Only Louisiana (79%), Michigan (77%) and Ohio (75%) have more native residents.  

Sure, 75% of Pennsylvania male deer disperse as yearlings, but they only average about 5 miles.  Every now and then there is an overachieving yearling that travels 20+ miles before settling down in an adult home range but that is hardly the norm.  

Fewer yearling females disperse (9-32%).  But when they do, they make it worth their while by traveling further (32 miles) before finding a place to call home.  

Once Pennsylvania deer settle into their adult home range, they rarely leave.  That’s why the rare exceptions are such anomalies.

Deer in Pennsylvania just don’t like to travel. At least compared to their western cousins. Compared to Pennsylvania whitetails, western ungulates are gypsies.  

And a new book shares the state-of-the-science about the landscapes of Wyoming and how large ungulates travel through it over time.

Wild Migrations: Atlas of Wyoming’s Ungulates is a collaboration of scientists and cartographers telling the story of animal movement in Wyoming.

Wyoming has plethora of ungulates – elk, mule deer, moose, bighorn sheep, pronghorn, white-tailed deer, and bison – and all exhibit migratory behavior. Our favorite ungulate, the white-tailed deer, is the least migratory of the bunch – they average 5-10 miles with some covering up to 40 miles and only 25-50% of Wyoming white-tailed deer migrate at all.

Then there is the Wyoming mule deer, the whitetail’s high strung and complicated cousin.  Some individuals annually migrate 150 miles between their summer and winter range. Yet some mule deer might not migrate at all – sometimes in the same herd! I told you they were complicated.  

Why all the variation? Because variety is the spice of life – and evolution. If future conditions change, some behaviors may be rewarded while others may not. The reward is successfully passing on genes to offspring. Having that variation in the population will increase the odds that a species will persist.

This book is also about the challenges faced by these animals in a changing landscape. Wyoming landscapes are negatively transforming for these ungulate species. Energy development, roads, a changing climate, and fences are affecting these large mammals and the news is rarely good.

But not all is gloom and doom. The book chronicles how government agencies responsible for managing these species are addressing these challenges. By asking a seemingly simple question (how and when animals move across the landscape), Wild Migrations opens the flood gates of the huge implications for protecting species and the wild places upon which they depend. 

These stories have shrunk our perception of the size of many of our public lands. Consider Yellowstone National Park, for example, the second largest national park in the continental US. One of our greatest national parks covers 3,468 square miles, yet the area over which the elk that summer in Yellowstone move is probably upwards of 20,000 square miles!

If you thought managing white-tailed deer in Pennsylvania was fraught with controversy and challenges, consider what Wyoming is facing with 7 species that travel tens to hundreds of miles on an annual basis.  

Wild Migrations is a beautiful book with data translated into images on almost every page. If you’ve ever visited or hunted – or plan to visit or hunt – in Wyoming, you’ll want to read this book.  

Maybe Santa’s globetrotting ungulates can get it to you in time for the holiday. 

-Duane Diefenbach and Jeannine Fleegle

If you are interested in purchasing a copy of Wild Migrations, you can order it here.  Check it out!

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Rain On Opening Day

We’ve written about the movements of deer in October – these have covered rain, the wind, and the dreaded October Lull, not to mention the rut. But we’ve never addressed weather in the rifle season because it is hunter activity in the woods that influences deer movements – and we’ve shown you lots of movies of how deer avoid hunters. My favorite is Hillside Doe.

But what about this year? It was one of the most unenjoyable from a weather perspective in recent memory.

About 8am on opening day I was hoping the rain was not going to be as bad as predicted. But I could see by the radar app on my phone that some heavy stuff was headed our way.

By 8:30am the rain was coming from the south. And hard! Glad that I had purchased lens covers this year for my scope, I noticed the water was beading up nicely on my newly-refinished stock. What fun!

By 9:30 the rains had made their way down to my lower back and were puddling in my seat pad. I had seen enough rain and no deer. I went back to the house.

My daughter was sheltered under a pine tree during the initial rain onslaught, so she wasn’t ready to give up yet and she headed up to the pines to sit. When she returned soaked and cold an hour or so later she only saw one deer. It was a sub-legal buck that watched her walking as he was bedded chewing his cud. When my daughter stopped he just looked at her and eventually got up and slowly walked away.

He didn’t seem to be in much of a hurry to leave his comfortable spot. Were other deer doing the same thing? None of my friends and neighbors saw many deer. But maybe that was just because most of us got wet and headed back to the house?

I thought if the weather on opening day would have an effect on deer movements, it would be this year. So let’s see what the data show.

I took all our locations of deer collected on the first Monday and Tuesday of 2013-2018. Six years of data! I only used locations between 6am and 6pm. My prediction would be that in 2018 there would be substantially less movement compared to previous years if the rain influenced deer as much as it influenced hunters.

If you’ve read our previous posts on weather, we found that female movements were less influenced by rain than were males. Males tended to move less when it rained.

I’d have to conclude weather had little effect on buck movements (males at least 2.5 years old). Although some years saw almost twice as much movement as other years (even between Monday and Tuesday!), there wasn’t anything unusual about our Monday opener this year.

Females showed no evidence of the rain on Monday influencing their movements. Females also show substantial variability among years – even between Monday and Tuesday.

I have two conclusions to take away from this little exploration of weather and deer movements during rifle season. First, the distance moved seems to vary from year to year, but we have no evidence the 2018 rain event greatly affected those movements. Second, if I didn’t get so wet and cold I should have kept hunting!

-Duane Diefenbach

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Holiday Happiness

Thanksgiving is here and the holiday season is officially upon us.  There will be pumpkin pie and stuffing and shopping and turkey!  

Yes, turkey is the highlight of the day…and potentially weeks after.  Turkeys definitely draw the short end of the stick during the holidays.  But sometimes eating turkey for dinner just isn’t worth the effort.  It seems to be the case for this coyote.

This may seem a bit out of character.  Why would a coyote be hanging with a bunch of turkeys?  He should be the laughing stock of the coyote community.  Be required to turn in his official “menace of society” card.  Coyotes are stereotyped as being killing machines leaving nothing but death and destruction in their wake.  

Research and data have shaped my opinion of coyotes, which does not jive with the stereotype.  I admire coyotes for many reasons.  Topping the list is their intelligence.  

Taking advice from Kenny Rogers, predators need to know when to hold’em, fold’em, and most importantly when to walk away.

Merriam-Webster’s definition of a predator is “an organism that primarily obtains food by the killing and consuming other organisms.”  What Merriam-Webster does not mention is that every trip to the grocery store for a predator does not result in a full grocery cart.

Predator hunting success rates vary.  Wolves in Scandinavia were successful less than 50% of the time on a hunt.  Wolves in Yellowstone were only successful 15-26% of the time depending on winter severity.  Spotted hyenas were successful about 1/3 of the time.  Merlins in Washington were successful in catching dunlins in 22% of attempts.  African wild dogs were successful in filling their bellies about 51% of the time.  Lions in Kruger National park were successful in about 30% of their attempts at obtaining groceries. Pennsylvania deer hunters are successful 34% of the time.

Yes, predators are not necessarily the killing machines they are made out to be. 

There are many factors that contribute to hunting success.  There are many times that predators don’t even attempt to capture prey because the odds are not in their favor.  Sure, predators have big teeth and claws and are fast or stealthy.  But prey can be very dangerous.  

Wolves in Yellowstone prefer to hunt elk over bison even though bison are more abundant.  Why?  Because attacking a bison is very risky.  If a wolf (or any predator) is injured during a hunt, he or she (unlike the prey) might not live to hunt another day.  

But it’s just not risk of injury that can deter a hunting attempt. Handling time, environmental conditions, body condition of predator, pack size, herd/flock size, and odds of being successful all factor into the Go/No-go call on the part of the predator.  

So why is our coyote hanging with these turkeys?  Maybe he just wanted to celebrate the holidays with some friends.  Sometimes success is measured by memories.  Ask the 800,000+ hunters heading into the woods on Monday.   

-Jeannine Fleegle
Wildlife Biologist
PGC Deer and Elk Section

 

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Patterning a buck in the rut

Since the inception of this blog, I have thought about the idea of patterning a deer’s movements using either game cameras or simply spending enough time in the woods. How would one do it?

Personally, I don’t have enough time to sit in a tree stand THAT long, and I don’t own enough game cameras. However, professionally I have access to GPS collared deer.  Evaluating movements with satellites is certainly more accurate.  (Note: I don’t deer hunt on the study areas!)

Over the past several years, I have made many movies of bucks during the rut.  The only pattern I can identify is that there is no pattern – there too many exceptions to any rule I can possibility think of.

This blog post is about such an exception. In a previous post we showed you a buck who had a bachelor pad. He spent his summers in one place and moved a couple miles away to spend the rut on his bachelor pad. Not many deer do this sort of thing.

Or so I thought.

I am going to show you the movements and home range of a buck during September, October, and November of 2017. This deer was captured on the Susquehannock State Forest and was at least 3.5 years old.

Before I start, I need to get a little technical. The first definition of an animal’s home range was published in the Journal of Mammalogy in 1947.  C. O. Mohr wrote that a home range was the “area traversed by an animal during it’s normal movements.” That’s fine but defining “normal” in a way that you can calculate a home range has been a challenge for quantitative wildlife ecologists for decades.

With modern GPS collars we can now get tens or hundreds of locations a day which has led to home range estimators that are getting pretty close to modeling the “area traversed by an animal during is normal movements.” I will be using 95% home ranges based on a Brownian Bridge Movement Model – suffice to say 95% of the time the animals’ movements occur within the home range boundary. This model works quite well.

Now that we are done with the technical stuff…

Let’s start in September 2017. His home range was a whopping 474 acres (0.74 sq. miles). This is actually slightly below average for a deer (male or female) in the Big Woods during this time of year. Here is a video of his movements for the month.

Not very interesting.

But check out what happens on the 17th of October! 

Now October is supposed to have the Lull. Not so much for this deer…

This deer’s home range is now 8.4 sq miles! So much for an October Lull!

The worst part is that if you got this deer on your game camera in September, you can forget about seeing him again for the rest of the hunting season. How sad is that?

Patterning a buck?  I’m pretty sure it’s an exercise in futility. 

In comparison to October, this buck actually “settled down” in November when his home range was 6.34 square miles. However, notice that he clearly starts making movements crisscrossing his home range in search for females.

Maybe some deer can be “patterned” during the rut. But it certainly isn’t going to be this one!  In fact, I haven’t found one yet!

-Duane Diefenbach

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Why did the deer cross the road…there?

Deer crossing signs are a Pennsylvania roadway staple.  One of my biggest fears behind the wheel is hitting a deer.  The purpose of a deer crossing sign is to alert drivers that the potential is higher in that particular area to see our favorite state animal.  

Because they are so common, many drivers don’t even notice those signs.  Not me!  After the sun sets, I’m on high alert and those signs increase my anxiety of realizing my nightmare.  

But why do deer cross more often in one spot than another?  I am using roads as an obvious example but the same applies to creeks, powerlines, ditches, or any other landscape feature.  We have all seen the muddy highway plowed by deer going over a bank.  They could cross anywhere but deer more often than not cross in the same place.

Being a biologist, I always looked at it in terms of cost/benefit to the critter.  There must be an upside to crossing in that spot.  Easier to follow a blazed trail.  Connectivity of habitat.  Something.

Then I read a paper about mule deer and white-tailed deer fence crossings in Montana.  Fences create barriers to movement across the landscape.  It is particularly problematic for species like elk and pronghorn that migrate and don’t like to jump.  

Deer, on the other hand, usually don’t have an issue with jumping so fences are considered semipermeable barriers.  However, research showed that almost half of the fence crossings were under, not over.  Interesting, but that really didn’t surprise me.  It cost more to jump so crawling is “cheaper.”  There is that cost/benefit thing again. 

What did surprise me was deer were using known crossing sites.  Deer didn’t just approach the closest fence section and then decide how to cross.  It wasn’t just chance that brought them to a particular place.  They were seeking them out.  These “known” crossing sites had bottom wires that were significantly higher than adjacent fence panels.  

Just like migration, ungulates appear to learn these fence quirks then pass on this knowledge.  If you are trying to make more wildlife-friendly fence crossing, this is kind of important.  Installing wildlife-friendly fence panels for deer or elk or pronghorn won’t do any good if they don’t know about them.  And they won’t know about them until they learn where they are which may take some time.

Ok, back to Pennsylvania.  It’s easy to see now why deer use the same places to cross roads or creeks or banks.  They have learned it perhaps for generations.  We don’t really need to worry about making it easier for deer to negotiate fences, but we can use this learned behavior to our advantage for things like deer crossing signs!  Or hunting near a well-traveled deer trail.  

-Jeannine Fleegle
Wildlife Biologist

PGC Deer and Elk Section

 

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Long Time, No See

People drift in and out of our lives all the time.  Think back to high school.  You might not even recognize people you saw on a daily basis back then.  You remember your shared history fondly, but time and circumstance has replaced them with others.  

With thousands of deer captured and tagged over the last 2 decades, the same thing happens with study animals.  We lose track of deer as projects are completed and radio-collar battery life wanes.

But it’s always nice to reconnect.  Doe 8101 was captured in the first year of The Deer-Forest Study (2013).  We tracked her movements for the next 5 years.  With battery life dwindling, we signaled the drop mechanism on the collar to retrieve it for refurbishment and future deployment. Unfortunately, we never received the signal that the collar dropped off the deer and we figured it was a collar failure.

Despite this un-dramatic ending, there are two interesting stories about Doe 8101. I’ll get to the second story later, but first Doe 8101 made an annual pilgrimage to the east every March. Not many deer exhibit these types of movements, but we’ve had several examples in the past. Some have summer homes and some have bachelor pads.

It looks like Doe 8101 takes a late winter vacation. Here are her locations for 2013.  Most of the year is spent in an area with a number of timber sales (plenty of food!!) but come March she treks several kilometers to the east.

Home range in 2013:

The obvious question is “Why?” And the obvious answer is “Who knows!” But of course we can speculate.

The area to the east has a southern aspect, so maybe the snow cover is reduced this time of year in those eastern locations.  We don’t see traditional yarding behavior in Pennsylvania deer, but they will shift their locations to more southerly aspects where snow depths are likely less taking advantage of the sun’s energy.

Or maybe she just likes the view that time of year.  Either way, she did it almost every year that we recorded her movements. 

Home range in 2014:

Home range in 2015:

In 2016 she did return to the area but only for two days in January! In 2017 she didn’t return at all, and after May 2017 we rarely got locations because the batteries were failing.

An interesting mystery for sure.  But like many of our interesting subjects, we completely lost touch with Doe 8101 after we received her location and attempted to drop her collar in January 2018.

In fact, later that month we found her collar in a pond! It was an inexplicable event. Was she harvested or poached and her collar dumped there? Was she hit by a car? What probably happened was someone found the collar and thought they would be smart and dropped it in a pond. Too bad for them – we got the collar back anyway!

But also guess what?  She just ran into a friend and sends her regards!  She’s alive and well…and still doing the mom thing.  

When we met her in 2013, she was at least 1.75 years old which means she is at least 7.5 years old today.  She hasn’t reached “old lady” status yet like some of our alumni.  She is squarely middle-aged which of course the is best age if you’re a deer.

We were happy to get a glimpse of Doe 8101 after all this time.  But seeing her left us with another question.  Did she teach some of her fawns to take those same annual vacations in March?!?

-Duane Diefenbach

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Life Before Google Maps

I love to travel.  Give me a destination and a computer and I can plan any trip!  I’m a bit obsessive about it but so are millions of others and we all write reviews.  There is a plethora of resources on the internet.  It’s easy to know where to go and how to get there.

But what did we do before we had all this information at our finger tips?

When I was a child, we took a family vacation every year to the beach.  My parents, grandparents, aunt, uncle, and cousins would load up and head east.  I can still picture the motel we stayed at, the pool, the beach, the strip with arcade games, and endless fried foods and cotton candy.  Place me back in my childhood home and I can even retrace our travel route.  

I learned this route.  It is not genetic or innate.  When behavior is a consequence of social learning and persists across generations, it is defined as culture.  For 3 generations, this route to the beach was passed on.  I no longer live in my home town.  If I had children, I would not be able to pass this knowledge on to them.  It would be lost.  

For me it’s not that big of a deal if my annual summer migration route is lost.  I do have the internet now.  However, it is a big deal for ungulates to lose their ability to migrate.  

Migration is the most amazing phenomena of the natural world.  Individuals traveling sometimes thousands of miles to reach their destination.  For ungulates, like deer, elk, moose, and big horn sheep, it allows them to maximize energy intake by riding the “green wave” across the landscape.  

RMNP Elk

But where does this knowledge come from?  Is it innate?  Learned?  Some combination?

Migration for some species is hardwired.  Take monarch butterflies for example.  Individuals migrating south every fall are on their maiden voyage.  Migration for them is completely grounded in genetics.  

The same goes for some bird species.  But not all.  Take captive bred whooping cranes.  They were shepherded on their first southbound migration route by human-piloted ultralight aircraft.  But that’s all they needed.  After that first flight, they migrated freely both north and south suggesting that cranes used both social learning and innate programming for migration.

Recent research has shown that migratory behavior in ungulates is learned.  In historical populations where 65-100% of individuals migrated, less than 9% of translocated animals migrated when moved into new areas.  The translocated individuals that did migrate were placed into existing populations that had been reestablished 3 decades prior. 

All translocated animals from migratory populations failed to migrate when placed into a new area to establish a new population suggesting that migratory behavior for ungulates is not innate or genetic but instead socially learned and culturally transmitted.  Like me, they needed someone to show them how to get to the beach!

Because migratory behavior is learned, it can be lost.  Humans created barriers that stop or alter migration routes or population extirpations can wipe out decades of social learning about spatial patterns of habitat resources.  Regaining this collective knowledge after it is lost might take decades.  While individuals are trying to re-learn, populations may suffer.

In Pennsylvania, we don’t have to worry about loss of migratory knowledge in our deer herd.  But we have had several individuals that make peculiar movements on an annual or predictable basis. 

Like Doe 17163 and 17157.  Two deer with completely different home ranges that travel to the exact same spot.  Or like Doe 8101 who takes a pilgrimage to the east every March.  

Did these deer learn this from their mothers?  Are there multiple deer that learned this?  Will it change over time if those individuals are removed from the population?

The answer to the last question is likely yes.

Is this a bad thing?  Probably not.  This isn’t the loss of migration route knowledge which has measurable population impacts.  They just won’t be able to find their way to the beach without Google Maps.

-Jeannine Fleegle
Wildlife Biologist
PGC Deer and Elk Section

 

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Summer Flashback

Buzztails on the move was in the back of my mind as I was hiking to a vegetation plot in the study area. Scenes like this one are a common sight in the summer as timber rattlesnakes search for mates. And then I saw them… latched together on the forest floor!

Coiled on top of one another in the open with their tails intertwined at the cloaca. Two stunning Timber Rattlesnakes—one black phase and one yellow phase—copulating. 

The large yellow phase paused to keep an eye on me, but the black phase (female) ignored my presence. Neither of them vibrated their rattles at me, though I was sure to keep my distance, so as to not disturb them.

The sighting inspired me to do a little more research on the misunderstood critters to shed some light on their slow reproduction and shy nature. 

Timber rattlesnakes-mating

Timber rattlesnakes coiled and mating

The reproductive biology of timber rattlesnakes is complicated. Males reach maturity at age four or five while females typically do not reach sexual maturity until they are 7-11 years old. Females in Pennsylvania are only capable of reproducing every 3-4 years after reaching sexual maturity. Since timber rattlesnakes can live to an average age of 20 years old, females may only mate once or twice in their lifetime but possibly up to three or four times. 

Sounds complicated, doesn’t it? Don’t worry, it gets more complex. 

Timber rattlesnakes-basking

Two timber rattlesnakes basking

Although most timber rattlesnakes leave their dens in the spring to forage, pregnant females tend to locate the nearest site to the den that receives continuous sunlight throughout the day to bask. Pregnant females minimize energy expenditure and maximize basking in the sun. They bask in the sun to increase their metabolism, so they can give birth in August or September. 

Rattlesnakes are sensitive! And I don’t mean that in the, “stays at home on the couch, eats a gallon of ice cream while listening to Barry Manilow’s ‘Can’t Smile Without You’” kind of sensitive. With a female breeding only a few times in her lifetime, and maybe taking a decade to reach sexual maturity, timber rattlesnake populations are sensitive to disturbances that reduce the survival or reproduction. 

They are just about the opposite of white-tailed deer. In a previous post we discussed which parameters in a deer population were most important to population growth. In deer it’s not fawn survival but rather adult female survival. But given that a white-tailed deer can breed at 6 months (although most give birth for the first time at age 2), they are still not nearly as sensitive to disturbance as timber rattlesnakes.

Although rattlesnakes don’t prey on white-tailed deer, they are predators and play an important role in the ecosystem. One snake can consume 2,500–4,500 ticks in a single season because mice and chipmunks are their main food source. In my book, that alone is reason enough to protect rattlesnakes.

But even though they are predators, they are also prey for hawks, eagles, owls, coyotes, raccoons, opossums, turkeys and other snakes.

Their coiled body, rattling tail and striking posture may seem intimidating, but timber rattlesnakes only want one thing – to be left alone. Venom is expensive.  It takes time and energy replenish it.  They are not into wasting a batch on something they cannot eat. They just want space.

Timber rattlesnakes-in bush

Timber rattlesnake in a low bush about 2 ft off ground

Timber rattlesnakes are not only beautiful and intriguing critters but a symbol of American history. A timber rattlesnake is shown on Gadsden’s “Don’t Tread on Me” flag and considered a symbol of the original Thirteen Colonies. Besides the wild turkey, Benjamin Franklin suggested that the rattlesnake would have been a suitable symbol for America. 

That’s a buzz I could definitely get behind!

-April Sperfslage
(Former) Crew Leader
PGC Deer and Elk Section

 

P.S. We would like to take this opportunity to recognize April’s hard work the past several years. April has accepted a new position in Louisiana working on a field project through Colorado State University. We greatly appreciate the contributions that April has made to The Deer-Forest Study and wish her well in her future endeavors! 

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Whitetails and Weather

Down South Hunting did a 3-part series on how white-tailed deer respond to weather and how it might affect how you hunt. They interviewed yours truly, and Dr. Bronson Strickland at Mississippi State University as well as others.

You can listen to the series on the web at these links

or you can download the podcasts on iTunes or Google.

October Lull – Version 2.0

“In like a lion, out like a lamb” is often used to describe March weather.  For deer, October could be described as “in like a lamb, out like a lion” with regard to breeding behavior.   It starts out slow but by the end of the month, things are roaring. At least for males.

Females are a slightly different story. Their goal this time of year – EAT.  As much as possible. 

Especially females with fawns – they need to make up for their huge energy expenditures (in the form of lactation) over the summer.  Just this past week I was watching a doe and fawn.  That little milk vampire was still trying to nurse. It didn’t last long.  Mom promptly put an end to junior’s free meal.

Females need to eat.  And it’s raining acorns.  Perhaps an October Lull?

The graph below shows hourly movements prior to October 1, 2017 (in yellow) and during the first three weeks of October (black). We have a lot more data on females and these data represent averages of 14-24 females per week.

The graph suggests slightly less movements during October than September.

October lull-females-G1

What is even more interesting is that movements don’t change that much during the rut.

October lull-females-G2

We’ve written about this before. During the rut, bucks are looking for females.  If you’re a female, you want to be found.  The best strategy – stay put!

Even home range sizes reflect this female behavior.  During the rut home range size of females is no larger than during October.

-Duane Diefenbach

Read previous posts on this topic:

October Lull – Take 2

October Lull

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