cc  >> Okay, I'd like to welcome  all of you to the Wisconsin  Historical Museum for  an Earth Day version  of History Sandwiched In.  Today, I have privilege of  welcoming Dr. Stan Temple, who  actually served in the same post  as Aldo Leopold at the  University if Wisconsin.  And he is going to lecture us  on A Sand County Almanac  and Climate Change.  So here he is.  (applause)  >> Thank you.  I'm glad to see so many of you  braving the blustery weather  today to come out.  How many of you have read  A Sand County Almanac?  Okay, I'm preaching to the  choir.  So you already know a little bit  about Aldo Leopold, and know  what A Sand County Almanac  is about.  And you know, of course, that  Sand County Almanac is really  this sort of culminating  accomplishment of Leopold's  career.  It was published  a year after he died in 1948. 

 And the setting, of course,  for much of the Sand County  Almanac, is Leopold's shack,  which is sort of depicted here.  The shack was the chicken coop  on an abandoned farm that  Leopold bought in 1935, and  where he and his family spent  most of their weekends.  So it's Aldo Leopold, the shack,  what he had to write about  in A Sand County Almanac  in a historical sense.  But in a more contemporary  sense, a lot of the things that  Leopold was observing and  writing about when he was at the  shack end up having some very  interesting implications for  understanding the consequences  of climate change for species in  Wisconsin.  So we'll wrap it up by sort of  tying the history to the present  day.  Aldo Leopold, throughout his  life, literally from the age of  7, kept a daily journal.  His mother Clara encouraged her  son to keep a daily journal.  And with Leopold's interest in  the natural world, much of what  he wrote in his journals was his  observations of what was  happening that day in the  natural world.  Although he probably didn't  realize it at the time he was  starting keeping these journals,  what he was really participating  in was the science of phenology,  keeping track of when things  happen seasonally, when flowers  bloom, when migratory birds  arrive, depart, and so forth.  And Leopold, being a keen  observer, kept careful notes on  literally hundreds of species  that he observed in his various  outings. 

 Leopold's habit was to have a  little pocket notebook in which  he would write things as he  would observe them in the field.  Then every evening, he would  transcribe those field notes  into his journal.  That is what he is doing in the  photograph here.  A large journal, in which he  carefully transcribed all of his  observations.  There are a couple of  interesting things about Leopold  and the keeping of these  phenological records, in that it  started more or less as a hobby.  But once he was sort of settled  in and regularly visiting the  shack, he started to treat it  more as a research project,  something that he was being very  meticulous about.  And it's basically about the  phenological records that  Leopold kept from the period  1935, when he bought the shack  until 1948 when he died, that  I'll be speaking today.  Leopold made everything that he  did at the shack, including the  phenological records, a family  affair.  So Leopold's children were all  sort of indoctrinated into  keeping these kind of records as  children.  It was a fun thing to do. 

 They all contributed to the  observations.  Here's the family at the shack.  His wife Estella, sons Starker  and Luna, and daughters Nina and  Estella.  His son Karl took the photo.  I'm going to point out a couple  of things that will be relevant  later on in the lecture.  The dog.  That's Flick.  And Flick will turn up again in  the story later on.  I'd also like to point out this  lilac bush at the corner of the  shack.  Mrs. Leopold planted that to  sort of spruce the place up, as  much as you could spruce up an  abandoned chicken coop. 

 But it will also have an  important role in the story that  I'll tell later on.  What Leopold eventually did,  of course, in A Sand County  Almanac, was that he took all  of his lifetime of phenological  records, and at least in the  first half of A Sand County  Almanac, the almanac part of the  book, what he lays out month by  month, are some of the iconic  events in the natural world, the  things that you might say are  the very conspicuous things that  are happening each month by  month.  It reflects, obviously, the  skills of a good naturalist, and  obviously of an excellent  writer, to tell these stories in  the engaging way that you know  that he did.  I'll give you an example,  because it's one excerpt that  not only shows how he picks an  iconic species, but how he  weaves subtly the science of  phenology into his essays.  As I said, the month by month,  he picks an iconic group of  species.  And for the month of July, one  of the iconic species is the  compass plant, a native prairie  species that Leopold picked as  the sort of featured species  for the month.  And here's what he had to say  in the essay entitled  "Prairie Birthday."  Every July, I watch eagerly  a certain country graveyard  that I pass in driving  to and from my farm.  It is extraordinary only in  being triangular instead of  square, and harboring, within  the sharp angle of its fences,  a pin-point remnant of the  native prairies on which the  graveyard was established  in the 1840s.  Heretofore unreachable  by scythe or mower,  this yard-square relic of  original Wisconsin gives birth,  each July, to a man-high stalk  of compass plant or cutleaf  silphium, spangled with  saucer-sized yellow blooms  resembling sunflowers.  Here's the phenology part. 

 This year I found the Silphium  in first bloom on 24 July,  a week later than usual;  during the last six years  the average date was 15 July.  The perfect iconic species.  It bloomed dead center of the  month.  And woven through many of his  monthly almanac accounts are  these little tidbits that show  you he's keeping track of things  in a very detailed sort of way.  Well, Leopold's journals are  fascinating to read in their raw  form.  They're written in a very  engaging way.  And there's an enormous amount  of information stowed away in  these journals, which are now  part of the Aldo Leopold  archives.  I thought I would give you just  an example of what Leopold's  journals from the shack looked  like.  This is a journal from April 21,  1939.  Seventy years ago. 

 This is what Leopold was  observing and writing about.  He's observing the weather.  At that particular phase of his  career, he was particularly  interested not only in the  timing of seasonal events, but  he's interested in the timing of  daily events, when various  species of birds first started  singing.  So he's got a section here  talking about when birds around  the shack first started singing.  And then, as you get down toward  the bottom, there's the  phenology of some of the things  that he observed for the first  time in 1939, April 21.  So he saw pussy toes, a small,  low-lying plant in first bloom.  And he notes the lilac, which  certainly was the lilac tree  planted at the corner of the  shack, that the buds were 5/8 of  an inch long.  So he goes on and looks at some  other things.  Interspersed are some stories.  So on top, he's talking about  winter mortality in deer mice. 

 All this spring, Flick the dog  has been nosing out and picking  up dead deer mice.  Today alone, he had three.  So he wonders then, well, what's  going on.  Why are all these deer mice  dying.  Was it the severe winter.  Was it some sort of disease.  And he said probably this  happens a lot, but I've never  noticed it until I had a pup  with a taste for carrion, or  anything else of his finding.  So he's attributing part of his  observation to Flick.  They did bird banding at the  shack.  So here are some of the bird  bands that they applied that  day. 

 And finally, he talks about  woodcock.  If you've read A Sand County  Almanac, you know that woodcock  are the iconic species for  April, and especially their  reproductive displays, breeding  displays of the woodcock.  So he's got an accounting here  of which of the woodcocks in the  vicinity of the shack are giving  their courting calls, and which  ones are sky dancing, doing  their aerial displays.  But again, what he wrote about  in the Sand County Almanac  is basically a reflection of  everything that he was observing  at the shack.  And eventually, by the 1940s,  he'd accumulated enough  information that he was able to  sort of try to put it all  together.  This was obviously in the days  before Excel spreadsheets, so it  was all done by hand.  But looking at when hundreds of  different events that he had  observed, when they were  happening, and looking at the  variation between years.  Obviously, it wasn't the same  every year.  So from these journals, Leopold  was able to extract what we  would now presumably say was  data.  It was information that he could  actually analyze and try to  interpret and figure out exactly  what was going on. 

 And he published it in 1947, the  year before his death.  A phenological record for Sauk  and Dane Counties in Wisconsin.  The Sauk County part of it was  Leopold's observations at the  shack.  The Dane County part of it  reflected a requirement of all  of Leopold's graduate students,  was that they had to keep  phenological records here in  Madison.  So he had a virtually daily  accounting of the phenological  sequence of events at the UW  Arboretum, where many of his  students were working.  So we've got Sauk County with  basically the weekend  observations that Leopold made,  and Dane County, where the  records were being kept  basically daily.  And when Leopold analyzed those  records, he realized that there  were some interesting patterns  that were interesting to try to  interpret.  And he did that in this paper,  Ecological Monographs.  His main point was to emphasize  that phenological records have  ecologic significance.  Up to the time that Leopold  wrote this paper, phenology was  not something that ecologists  really bothered with. 

 It was something that sort of  natural historians sort of did,  more or less as a hobby.  Sort of like Leopold did for  much of his life.  They never really tried to make  anything out of it.  It was just something that was  sort of fun to do.  But Leopold, being a scientist,  saw that there were patterns in  it.  Some of it is things that you  might say were obvious.  He detected that there seemed to  be a very slight difference in  the timing between Dane County  and Sauk County, with things  happening a little earlier in  Madison than at the shack.  He also noted, because he'd been  keeping those records for a  number of years, that there were  definite correlations with the  arrival of spring.  Early, warmer springs, some  things occurred earlier.  Colder, later springs, some of  those things occurred later. 

 He also noted, because of  course, he was looking at  hundreds of species, something  that most other people who did  phenological studies didn't do.  They would focus on one thing.  They would focus on, you know,  the daffodils in their garden,  or whatever, but not hundreds of  wild species.  Leopold, because he looked at so  many species, he was able to  show that there were differences  between species in how they  responded to say, differences in  spring weather.  Some species responded to the  weather and others didn't seem  to respond at all to what was  happening in the spring.  So, he wrote these up.  And sort of as a message to  ecologists, he pointed out that  what we can learn from  phenological records, obviously  has ecological value.  And the value definitely  increases as you accumulate more  data over more years, and over  different geographic areas.  And he sort of encouraged  ecologists to start keeping  phenological records on their  study sites.  That was in 1947. 

 Leopold died a year later.  And his string of records at the  shack came to an end.  And it appears at least from the  ecological literature that no  one really paid a lot of  attention to Leopold's call for  ecologists to pay more attention  to phenology.  It continued as an endeavor.  But again, it was mostly  amateurs who were doing this  more or less as natural history  studies.  That is, until many years later,  when Leopold's daughter, Nina,  in her retirement, moved back to  Wisconsin and built her home  just down the road from the  shack.  And having grown up in the  Leopold household, and with all  of the traditions of the shack.  In 1976, Nina began keeping  phenological records at the  shack the same way that her  father had many years earlier.  And Nina kept at it in a very  detailed sort of way, trying to  replicate the types of species  that her father had tracked.  And of course, since she lived  there, she was able to do it  every day. 

 It became part of Nina's daily  routine, to go out in the  morning for a walk, and walk the  trails and see what was  happening.  And Nina also published a paper  in 1999, summarizing not only  her observations, but a  comparison between her  observations and her father's  observations from decades  earlier.  And the point of her paper was  that the phenological sequence  of the shack had changed since  her father's time.  And it had changed in a  direction that clearly was sort  of correlated with the climate  change that were now aware of in  1999, that many things were  happening earlier than they did  during her father's time.  And of course, we know from the  tracking of weather data, that  indeed, spring is occurring  earlier in Wisconsin than it did  in Leopold's time.  This is a summary of 57 years,  looking at when we first have a  string of ten days in a row, in  which the average temperature is  50 degrees or above.  That's usually right about now,  late April or May, when we would  reach that point.  And the map sort of summarizes  the 57 odd years.  And it's showing that at least  in the southwestern half of the  state, that spring is arriving  anywhere from a week to two  weeks earlier than it did back  in 1950.  Whereas in the northeastern part  of the state, things haven't  really changed that much. 

 But the shack is of course here,  so it's experiencing an advance  in the arrival of spring of a  week or so.  So Nina, in her observations,  observed something that her  father had of course sort of  realized as well.  And that is that species don't  respond the same to year to year  variations, which is what he  observed.  And Nina observed that they  don't respond either over long  periods of time, when the  climate has actually changed.  In fact, she found that some  species did respond to the  earlier arrival of spring, and  other species didn't.  She looked at 55 springtime  events.  These were the ones that they  had the most data for from her  father's era and her era.  And she found that there's  actually a lot of variation.  Thirty-seven of those events,  the blooming of flowers, the  arrival of birds, and so forth,  actually advanced.  But 18 events showed no shift at  all. 

 They were still occurring at  exactly the same time as they  had in Leopold's era.  So she was interested in  that fact.  And to show you some examples of  some that do and some that  don't, if you look at the  blooming of columbine, one of  our distinctive spring  wildflowers.  In Leopold's era, the average  first bloom was May 19.  In the later data set, the  average first bloom was May 9.  On the other hand, dogbane a  species that blooms in June, in  Leopold's time, June 19.  In recent times, June 20.  No response at all to the fact  that the spring climate is  getting warmer.  It sort of illustrates that not  all species respond in the same  way to climate change.  The compass plant that used as  his iconic species for July. 

 In Leopold's time, dead center  in July, the perfect icon.  Now, first bloom is June 26.  It no longer would even be  appropriate to put the compass  plant in as the iconic species  for July.  It's now blooming three weeks  earlier.  One of the things that Nina  noted was that the species of  plants that most consistently  responded and advanced their  phenology were the plants that  bloom in very early spring.  So things like pasque flower,  one of the first blooming plants  on the prairie.  In Nina's time, was blooming  nine days earlier than in her  father's time.  Bloodroot, a woodland species,  two weeks earlier.  So there were some very  interesting patterns in the  plant data.  But there were also some  interesting patterns in the bird  data. 

 Leopold was a great bird watcher  all his life.  We don't think of Leopold as a  bird watcher, but if you look at  the photos of Leopold, you  realize any time he's dressed  for the field, he's got a pair  of binoculars around his neck.  But what Nina observed was that  for resident birds, for birds  that stay around in Wisconsin  throughout the year, they were  showing an advance in when they  first began their sort of  territorial behavior.  So cardinals, for example, were  starting their territorial  singing earlier than in the  past.  The same was true of short  distance migrants.  The migratory birds, that most  of them leave Wisconsin, but  they don't really go that far  south.  They may go a few hundred miles  to the south.  But they tend to not go that  far.  They also showed an advance, in  that they were arriving earlier  than they did in Leopold's time.  And of course, any of you who  are bird watchers know that now  many robins don't even leave at  all. 

 They actually spend the winter  here.  But this was in contrast to  another group of birds, the long  distance migrants.  These are the ones that go all  the way down to Central America,  the Caribbean and South America.  And in this case, picking a wood  thrush, which is actually a  close relative of the robin, you  can see that this long distance  migrant is arriving at exactly  the same time that it did back  in Leopold's time.  The explanation for this is  rather interesting.  The short distance migrants and  permanent residents are actually  responding to temperature, to  know when to start singing or to  know when to come north to their  breeding territories.  The long distance migrants,  coming from South America, they  don't have a clue what the  temperature is in North America.  They're timing their seasonal  migration by photo period, by  the length of the day.  And that of course, doesn't  vary.  So they're on the same calendar  every year regardless of what's  happening here in Wisconsin. 

 So Nina's paper revealed that  many of these spring events were  advancing, and that it appeared  that it was advancing within her  data.  Within the more recent data, it  was advancing at about one day  per decade, things were  occurring earlier.  And the most obvious explanation  was that this was correlated  with climate change, global  climate change.  Well, the paper, you know, got  some attention.  It was one of the earlier  papers talking about varieties  of species responded to climate  change.  But it was an effort that was  vulnerable.  As we all know, there are people  who don't believe that climate  change is happening, and would  certainly deny that there are  any consequences.  So they were quick to pick on  papers like Nina's, in which  they could find there was some  flaw in the methodology that may  have made her results a little  less trust worthy.  And Leopold himself, Aldo  Leopold, in his early paper, he  did caution.  He said it was tricky to make  comparisons between phenological  data if they weren't collected  in exactly the same way. 

 And as it turns out, Aldo's data  and Nina's data were not  collected in exactly the same  way.  There were some systematic  biases that may have resulted  in a bias in her conclusions.  And the main one, the one that  was most obvious, was the  interval of the observations.  And as a general example, if you  only make observations on  weekends, it's possible that you  would miss the first robin to  arrive, or the first plant to  bloom.  You could miss it by as much as  five days.  It could have happened on  Monday, and you didn't detect it  until Saturday.  And obviously, that's not a  problem if you're making the  observations daily, where you  would obviously not have any  sort of lag in your ability to  detect what was happening.  Well, of course, therein is the  basis for the bias.  At the shack in Aldo's time, the  observations were irregular.  They were only on weekends and  holidays, whereas the  observations in the recent time  were almost daily. 

 That tends to make the irregular  data from 1935-47, appear to be  later than the more recent data  that was collected in a regular  sort of way.  So with the help, actually, of  Jennifer Sontag, one of the  students who helped me go back  through Aldo Leopold's journals  and figure out when he was at  the shack and when he recorded  things, we were able to sort of  unravel how much of this bias  was actually influencing  results.  And you can see it in a species  like shooting stars, a very  conspicuous flowering spring  plant.  The average first bloom at the  shack was May 22, according to  Leopold's journals.  But if you go through and look  at his data, you realize that  there is always the possibility  that he missed it by as much as  five days.  And in fact, the average could  have been as early as May 16.  That he could have missed it,  essentially, by almost five  days.  If we look at the bias, of  course, the average first bloom  in Nina's data in the recent  data was May 15.  The average first bloom that  Aldo observed was May 22.  But it could have been as early  as May 16, which essentially  eliminates what looks like a  very striking advance in the  blooming of this particular  plant. 

 And obviously, this is the kind  of flaw that critics of climate  change love to pick apart and  say, aha, see there is nothing  really happening there at all.  So there was another interesting  source of bias having to do,  again, with observation  intervals.  The early data at the shack of  course were less frequent early  in the year.  The family wasn't going to the  shack as often then.  The weather wasn't nice.  In fact, it averaged almost ten  days between visits.  Later in the year, in May and  June, when the kids were out of  school and the weather was nice,  they were visiting more  frequently.  And obviously, Nina's  observations, again at the  shack, were just as frequent  early in the spring as they were  later in the year.  That means that at least some of  what Nina concluded was the more  advanced things happening  earlier in the spring could have  again, been due to this bias  between regular and irregular  observations.  So, looking at the data, we were  able to sort of account for this  bias. 

 And whereas just an average for  the recent data appeared to show  that the average for these  55 spring events advanced  by 7.3 days, in fact if you  account for the bias, it  could have been only 4 days,  if you eliminated the bias.  But for those who are critical  of data like this, there is  still in the data, solid  evidence that spring events are  occurring earlier.  And in fact, since Leopold's  time, it has been pretty  consistently advancing by about  one day per decade.  Just exactly what Nina had  detected in her own data set.  So it looks as though certainly  the paper did illustrate that  things are happening earlier,  and that the obvious correlation  is with climate change.  If you remember the graph of  spring temperatures, this area  of Wisconsin is in fact having  the arrival of spring occur  about a week earlier.  Seventy years of data, from  1935, and you end up with about  one day of advance per decade.  Exactly what the physical  meteorological records would  indicate.  So Nina and Aldo were  vindicated.  And it still stands as strong  proof that climate change here  in Wisconsin is having an effect  on many, many species. 

 So what?  Things are occurring earlier.  Many people would consider that  to be a good thing.  The interesting thing about the  Leopold's data sets is that they  were recording the phenologies  for hundreds of species.  They were able to show that not  all species were responding  exactly the same way.  And therein is the ecological  dilemma, in that if species are  not responding the same to  climate change, species can get  out of sync with one another.  Pollinators may not be emerging  until after the flowers have  bloomed, and therefore won't be  serving as pollinators.  If species are competing with  one another, the one that  responds and gets there earlier  is the early bird that gets the  worm.  The one that arrives later might  be out of luck.  So the Leopold data set is a  wonderful data set to explore  for these little ecological  dramas that are playing out,  that can be observed in the data  set.  I'm going to give you a couple  of examples that show what might  happen if things get out of  sync, or you know, for some  species, if things remain in  sync. 

 This particular story here is  one that Leopold wrote about  when he was in high school.  He was playing hooky.  That's the only way I can  describe it.  He was skipping classes and  going out bird watching early in  the year.  And he observed something  interesting.  Skunk cabbage, one of our  earliest blooming plants is,  like its name implies, it  stinks.  It has a very strong odor.  On average, in Leopold's time at  the shack, it bloomed for the  first time on April 1.  More recent data, on March 18.  Leopold observed when he was  just in high school that there  was an interesting correlation  between the blooming of skunk  cabbage and the arrival of the  phoebes. 

 Pheobes are one of our earliest  arriving short distance  migrants.  And again, phoebes arrived about  a week later than the skunk  cabbage back in Leopold's time,  and about a week later in more  recent times.  You might say, well, so what,  they're just two species that  are responding the same way to  climate change.  Well, it turns out, Leopold's  observation was that when  phoebes arrived very early in  the year, they feed on insects.  And there's a possibility of  course that they'll encounter  bad weather, in which there  won't be any insects out flying.  And Leopold observed that the  one reliable source of insects  was at the skunk cabbage plant.  And he pointed out that if you  go early in the year and sit  down at a skunk cabbage plant,  you'll probably see a phoebe  come and catch the flies that  are attracted the stench of the  skunk cabbage.  So here's two species that  stayed in sync with one another.  Phoebes still have their sort of  emergency food supply if they  arrive and the weather is bad.  They can seek out a skunk  cabbage and be sure that they'll  find flying insects. 

 On the other hand, here's a  story that doesn't have a happy  ending.  The great crested flycatcher is  a long distance migrant.  It winters down in the tropics.  And because its timing its  migration by photo period, it's  still arriving at almost exactly  the same time as it always did.  In other words, it's not  responding to temperature at  all.  It's responding to daylight.  Well, the problem for great  crested flycatchers is that they  nest in cavities.  And unlike woodpeckers, they  can't make their own cavities.  They have to find an existing  cavity in order to nest in.  And for birds like this that  don't have the ability to make  their own cavity, there is  intense competition for suitable  nesting cavities. 

 And literally, the bird that  gets there first wins the  intense competition.  And in the case of the great  crested flycatcher, now many of  the short distance migrants and  permanent residents, birds like  the starling, for example, are  now advancing their nesting  cycle, and they're occupying all  of those cavities several weeks  before the crested flycatchers  arrive.  In fact, by the time the crested  flycatchers arrive, birds like  starlings even have babies in  the nest.  So the great crested flycatchers  have been put at a severe  disadvantage.  Does it make a difference?  Well, I'm not saying that this  is the cause of the decline, but  if you look at what's happened  to great crested flycatchers  since 1966, when the North  American Breeding Birds Survey  started keeping track, in  Wisconsin, the great crested  flycatcher has declined by about  35%.  And the sort of loss of ability  to compete successfully for  nesting cavities certainly has  contributed to its inability to  maintain its numbers.  So what did the Leopolds tell us  basically?  Well, they told us, obviously,  that hey, phenological records  are important to get ecological  insights, especially at how the  species in an ecological  community are responding to  climate change, and especially  how these little sub-dramas of  the interactions between species  could be playing themselves out.  They also revealed, because  their records were so  meticulous, that you have to be  careful when interpreting these  data.  You can't sort of treat them in  a simplistic sort of way.  You need to be really careful  about how you interpret these  records, because even slight  differences in methodologies can  lead to big differences. 

 So we owe a lot to Aldo Leopold.  Obviously, not the least of  which was his contributions to  the science of phenology.  Now I suspect if in the pantheon  of phenology, Leopold occupies a  lofty place.  Obviously, because of  A Sand County Almanac,  probably one of the most  popular books dealing with  phenology, but also because  of his contributions  to the actual science.  Leopold's legacy, of course,  extends in other areas as well.  In my retirement from the  academic position that Leopold  once occupied, I'm now a Senior  Fellow at the Aldo Leopold  Foundation, which is just down  the road from the shack.  The Aldo Leopold Foundation is  of course dedicated to  perpetuating Leopold's legacy,  and promoting his ideas,  especially his ideas about the  ethical relationship between  people and the land, the science  of land, health and conservation  leadership.  The Leopold Memorial Reserve now  exists around the shack, which  is located centrally there.  It's an area in which a lot of  work is done, sort of  perpetuating Leopold's ideas  about maintaining and restoring  the health of the land.  And a couple of years ago, the  Aldo Leopold Foundation moved  into their new headquarters,  which I encourage you to visit. 

 At least for the time being, it  is the greenest building in the  world.  Although someone pointed out,  sort of irreverently, we were so  proud of all the modern  technological advances that had  made this building so  sustainable, and everything.  And someone pointed out that  maybe the shack was really the  first greenest building in the  world.  But in any event, both the old  and the new are there for you to  visit.  Another thing that you might be  interested in doing is going to  the Aldo Leopold archives.  All of Leopold's archival  material is now available  online.  You can go to the material.  Fortunately, the Aldo Leopold  Foundation and the UW Archives  got a large grant to digitize  all of Leopold's material.  So you can go and look at his  daily journals, and find out  what he was observing, basically  almost every day of his life.  You can find it just by Googling  Aldo Leopold Archives. 

 This is, of course, where Jenny  looked at all these journals  over the years and was able to  abstract the information that  allowed us to do the analysis.  The Leopold Archives also have  lots of other, sort of  artifacts, and memorabilia  from Leopold's life.  And one of these is actually  particularly relevant  to April 21.  Because April 21, 1948,  was the day that Leopold died.  He died, had a heart attack,  paid the price for being a  lifelong chain smoker, when he  ran from the shack to a  neighbor's property to try to  put out a wildfire.  He suffered the heart attack  while he was fighting the fire.  The little pocket notebook that  I said he always carried with  him was in his pocket.  The grass fire swept over him  after he had died.  But if you read down, Leopold's  last written words were a  phenological observation,  presumably of the lilac tree at  the shack.  "Lilac shoots 2" long."  Thanks. 

 (applause)