December 28, 2011

2011 in pictures--photographically speaking

The local newspaper ran a couple of special pages today with their photographers' favorite photos from 2011.  I thought it would be a fun way to close out 2011 on the blog.  I have a Flickr site, to which I upload photos that were fun to take, have some meaning, and turned out decently.  Here are the top photos that I uploaded in 2011, as judged by the number of 'views' and 'interest rating' they received on Flickr:

Himba boy near Kamanjab, Namibia.

My Dad's grain truck, from the mid 1960's that still is used
every fall.  They don't make them like this anymore.

River runs through it: valley view from the Brandberg, near Uis, Namibia.

Stripes lined up: Etosha National Park, Namibia. 

Worlds colliding: Two forms of transportation--Damara people
near the Brandberg, near Uis, Namibia.

Pemaquid Point Lighthouse, Maine.

Dancing droplets: Irrigation of corn in the Nebraska Sandhills.

Flamingo flood, Namib Desert: Heavy rains in Namibia during
January-May of 2011 created waterbodies where none had been
in recent times. These flamigos found a wide river in the
Namib Desert, near Walvis Bay.

Upland Sandpiper: near Rose, NE

Biplane aerodynamics: Morning in Nebraska Sandhills, along a road.
There were tens of dragonflies resting on plants, like this.
I took the photo from my pickup, driving slowy forward and
snapping lots of angles until I got straight in front. I like this one the best.

Eastern Kingbird: near Rose, NE.

Drafting: Snow Geese and jet near Kearney, NE.

A quiet courtyard in the old city of Barcelona, Spain.

December 16, 2011

Around the world with gorillas

A male mountain gorilla chews on vegetation while tourists
watch in Rwanda (photo by Reid and Gus Bates).
Our family met the Bates family from Louisiana while we were on our sabbatical in Namibia. They were also on a Fulbright fellowship, and our kids went to the same school in Windhoek.  We had some great adventures (here, here, and here) during 2009.

While we settled back in the States, the Bates family found another opportunity to travel in Africa...with another adventure to Rwanda. They recently had the opportunity to mingle with mountain gorillas! You can read about their exciting day by going to their blog here. In short: they paid to spend the day sitting in the forest just feet away from a group of gorillas!

The Bates' experience is just one more example of innovative ways to support conservation. As we look to the future in the Great Plains and the world...innovative solutions are going to come in many forms.  And, they will not be easy.

On their blog, Gwen sums it up well:

The gorillas are truly one of the few great natural resources that Rwanda possesses. They bring in millions of dollars to the economy in terms of tourists buying permits, paying for accommodations, spending money on food and souvenirs, drivers and petrol. They unfortunately are under great pressure from loss of habitat, poaching, and disease. It’s quite a balancing act that has to take place to keep all the elements in equal proportion and not letting one element tip the scales. How long Rwanda can continue to do so is anybody's guess.

Clean-up on aisle 12...!

(Photo by Mark Havnes | The Salt Lake Tribune) An Eared Grebe waits in a box on
Wednesday to be released after crash-landing in Cedar City on Monday night
apparently thinking some areas were water. At least 1,000 birds died
and 2,000 survived to be transferred to reservoirs in Washington County
(text from the Salt Lake Tribune).
Making news this week: the crash-landing of thousands of grebes in a Walmart parking lot in Cedar City, Utah.  The death toll looks to be about 1,500 birds according to press accounts.

Evidently, the birds were migrating in a storm and mistook the parking lot for a lake surface.  There have been myths about ducks mistaking the blue football field at Boise State (Idaho) for a lake, but they appear to be untrue.

Ecological traps are situations in which animals respond to cues, which normally would lead to enhanced survival or reproduction.  But, in an altered landscape, those cues can be misleading---leading to the 'trap' of misinterpreting the cue.

A typical example of an ecological trap--birds respond to the density of non-native, cool-season grasses in the spring to build a nest.  Throughout recent history, native cool-season grasses were mixed with warm-season grasses and forbs, which provided cover and sources of insects (for food for chicks) later in the season.  Early growth of grass would normally indicate an area that would be good for nesting and rearing young.  But, where non-native brome grass has overtaken a pasture, for example (wonderful forage grass for cattle), the forbs and warm-season grasses will not 'show up' later in the nesting season.  The birds, of course, do not know this, and the situation may result in reduced productivity...hence, a trap.

As my research lab continues to work with habitat selection of grassland birds, we may find more examples of ecological traps.  But, none will probably seem as harsh as the reality of crash-landing on pavement. 

December 14, 2011

Why we do what we do

It is the end of the semester, and life gets a bit crazy for students and their professors these days.  During grading of final exams, one can start to ponder why one didn't go into a life of research (no teaching) or running a car wash or some other job that does not require the grading of 5 pages of essays for 45 students.  Not saying it's happened to me, but it might have. 

The alternative job that I would most enjoy would be to be the 'car guard' in the parking lot of a grocery store in a country like Namibia.  Well, specifically Namibia.  I watch your car while you shop and you give me 50 cents. 

The allure of such a prestigious car guarding position can be so great that it is nice to be reminded 'why we do what we do' at the University.  A couple of things recently bounced me back from my foggy dreams of standing on tarmac, watching the shoppers with their treasures.

Josiah Dallmann, sophomore Fisheries and Wildlife major at UNL, explains
his undergraduate research results to fellow delegates at the Midwest Fish
and Wildlife Conference in Des Moines, Iowa.
Last week, four of my students and I participated in the Midwest Fish and Wildlife Conference in Des Moines, Iowa last week.  Students had the opportunity to share their research results and mingle with biologists and managers from across the Midwest.  I went to my first MFWC in 1990 as a graduate student at Iowa State, so am starting to be 'one of the old guys'--although not as old as I made my former advisor feel when I introduced my students to him as his 'academic grandchildren...'  It is always good to meet with colleagues and share this experience with students. 

I make no apologies for trolling social media, because it is an enjoyable passtime for an introvert who has made certain life choices and wants to watch others exploring the choices that I discarded.  Biologists who work for NGOs or agencies.  Friends who decided to stay in my hometown.  Colleagues who selected different regions of the country for their careers.  All worthy choices, and the what-if game is fun as you page through postings of first babies, hunting trips, and new puppies.

Stephanie Walden, UNL Fisheries and Wildlife alum, suits up for a low-level,
aerial waterfowl survey.  Photo stolen from Facebook.
But, I do take my share of ribbing about spending time on social media.  And, then a photo like this pops up, and you realize--this is the other reason you troll if you are a teacher: to see if anything, anything, anything at all rubbed off on your students. 

Nice job, Stephanie!  I enjoyed seeing your excitement as you suited up to do your first aerial waterfowl survey.  Made my day.

December 2, 2011

Compensatory harvest mortality in deer?

Two fawns find food and water during November in southeast Nebraska.
Photo by Larkin Powell.
The December 2 issue of the Lincoln Journal Star carried an insightful Letter to the Editor, regarding deer harvest.  I'm currently covering 'harvest management' in my Wildlife Management Techniques course.  The concept of Compensatory Harvest Mortality is often over-simplified or applied in a misleading manner.  Because it is hard to explain the concept to wildlife students, it was nice to see a glimmer of appreciation for the concept from a member of the public.

Compensatory Harvest Mortality, in short, is the concept that hunting (harvest of wild animals) does not always result in a net reduction of the population (we call situations in which harvest does result in a net reduction, Additive Harvest Mortality: harvest 'adds' to other forms of mortality).  Think of a situation in which you can make an annual count of a wildlife population immediately before harvest occurs (this rarely actually happens in the US, but happens in many other countries through 'game counts' on private land).  OK, so you have 100 deer or 100 quail on a piece of property.  Now, harvest happens (in the fall, normally), and 20 animal are removed, leaving 80.  Those eighty animals have to survive through the winter, spring, and summer until the next count, and they also will be mating and having offspring.

If a species has completely Additive Harvest Mortality, those 80 animals survive and reproduce at the same rates that the 100 original animals would have.  Survival and reproduction do not adjust to the new population density.  The 80 animals will have fewer offspring than 100 animals would have had, and the 20 animals removed will add to the number of animals that die from other causes.  If the probability of surviving a year for that species is 75%, then 75 would have survived without harvest.  But, only 60 survive from the 80 that were left after harvest.

But, in a Compensatory situation, the 80 animals that are alive after the harvest will now have higher productivity (more offspring/female) or higher survival, because of the lower density.  More food per animal equals better nutrition equals higher survival or bigger clutches/litters.  It is possible that the net result, measured in the following fall, could (and stress: could) be that the effect of the harvest has been erased by the ability of the remaining individuals to reproduce or survive at higher rates when they face less competition.

Obviously, Compensatory harvest mortality is the optimum situation for harvest biologists (people who set regulations for hunting) who want to provide opportunities for many people to hunt and take game animals.  The problem is that we rarely understand wildlife populations in enough depth to document the effects of density on reproduction and survival.  We have such data for quail (although there is still disagreement) and deer; recently my research lab provided indirect evidence for prairie-chickens in southeast Nebraska and there is some suggestion from the Nebraska's annual wing counts that prairie-chickens produce more young/adult when the breeding population is smaller.

With that, here is the excerpt of the letter from a Lincoln resident in the Lincoln Journal Star:

"This letter is in response to "Lengthen deer season" (letter, Nov. 23).  The writer stated that the "deer population has gotten way out of hand" and that "Nebraska Game and Parks should have a lengthier season."

"I disagree with this for the following reasons.  Studies show that the more deer are hunted, the more they compensate by having more offspring.  After a deer season, when a high number of animals are killed, two things occur.  First, there is more food for the remaining deer, which helps trigger increased reproductive rates.  Second, nature's reaction to the loss of large numbers of deer during a short period of time is for a greater number of does to ovulate and mate at an earlier age.  This increased reproductivity in heavily hunted areas can result in abnormally high deer populations year after year.

"Studies also show that in nonhunted, unmanipulated wild areas that have an optimum number of predators, deer populations tend to stay at or just below the maximum number the habitat can safely support.  Since all game animals in Nebraska are managed to promote hunting, to lengthen the deer season will only result in more deer, not fewer."

A proud youngster with his first buck. 
If bucks are removed without harvesting
does, the result can be higher populations
as the does are left with many resources
and fewer competitors for food.  The necessity
to harvest does has been reinforced by
recent regulations for 'earn a buck' (harvest
a doe before you can harvest a buck) in
many hunting districts in Nebraska. 
Photo by Larkin Powell.
So, a couple comments:

First, the writer nailed the concept of compensatory harvest mortality in the first 'reason' stated: increased reproductive rates are triggered by lower densities.  Nicely worded.

And, second, the writer did a nice job of summarizing how this can happen--higher pregnancy rates (percent of does that are pregnant) and more young does that are pregnant (thereby increasing their lifetime contribution of fawns to the population).

However, the writer overstates the impact of the 'hunting effect'.  Hunting does not result in "abnormally high deer populations year after year".  And, a longer deer season would not result in"more deer" than a shorter season.  If deer had the capacity to have 8 or 10 or 15 fawns at a time, then this type of response might be possible.  But, deer can have 1 (common), 2 (sometimes) or 3 (rarely) fawns.   While they can respond with higher reproduction, they are limited by their species' reproductive potential--it only compensates for increased harvest to a point. 

It is very possible to harvest more deer than the population can compensate for.  In fact, wildlife biologists count on this fact.  This is exactly why Nebraska Game and Parks Commission has increased the number of permits, especially for does, in the past few years.  And, it is why they have lengthened the season--an October 'antlerless' (does and fawns only) season was added to the normal November season to help reduce deer numbers.  To take the example to the extreme, if a longer season and cheaper licenses resulted in reducing a population of 100 does to 10 does, there is no way that the 10 does could reproduce at rates high enough to make the population higher than 100, as the letter-write infers.

Managing wildlife populations always involves stakeholders.  This is an example of how important it is to keep educating the public about the reasons for management decisions.  Kudos to the author of the letter,  however, for explaining the concept of Compensatory Harvest Management.  I may use the letter in my class next year, rather than my long-winded explanation...!