Skip Lisle & Alex Hiller at 2009 Beaver Conference in Lithuania
Hi Heidi,
you are receiving the summary of the first lecture day – September 21, 2009, – at the 5th international Beaver Symposium. I had to solve unexpected difficulties in getting Internet access. Proudly wearing your “Worth a dam” T-Shirts Skip Lisle immediately recognized his adventures in Martinez , CA, when getting sight of me just after breakfast. Another participant from Denmark pointed at my T-Shirt telling me that he knows about it via Internet
Skip is well known to the citizens of Martinez, CA, for the construction of a “castor master” beaver dam flow device in Alhambra Creek one and a half year ago. His talk at the end of the second lecture day was the most practical and instantly useful of the whole conference. If anybody wondered what could be done about flooding problems regarding co-existence with beavers, Skip would have the proper solution at hand.
From the presentation of Peter Busher: Darwin and the elephants
“Beavers, in a population sense, can be regarded as `mini elephants`, since they are also relatively large (for rodents), long lived and have few predators (other than humans) in most natural situations.”
Prof. Peter Busher from Boston University, Massachusetts, as chairman of the scientific committee referred to Charles Darwin who developed 250 years ago on the population dynamics of elephants his evolution theory. DarwinŽs famous book “The Origin of Species by Means of Natural Selection or the Preservation of Favored Races in the Struggle for Life”was published in 1859. Moreover in 2009 it is the bicentennial of Darwin (1809 – 2009 ).
According to Busher Darwin had developed an exponential growth equation, that given one elephant cow starts calving at the age of 30 for the consecutive 60 years until death meanwhile giving birth to a calf every three years that reaches maturity itself following the same scheme we should expect 19 million elephants to live on earth within a surprisingly short period of time. In fact we know that such kind of equations cannot come true according to loss of habitat, hunting, disease, accident, wildfire, extended drought etc..
Busher insisted on long-term investigations “since any short-term study does not allow
a full understanding of the natural pattern of change in beaver populations: The general long-term pattern is one of slow initial growth, exponential growth (traditional “J” shaped curve ), decline and stabilization around a carrying capacity”.
For example the number of beaver sites in Voyagers National Park, Minnesota, increased from 50 to 360 between 1940 to 1985 whereas the number of beaver individuals throughout the entire state of Massachusetts increased from 22500 to 65000 within 8 years from 1994 to 2002 according to Busher. What was rich growth, what was poor
growth ?
Change in population size occurs regardless of the density, populations fluctuate over the time, finished Peter Busher his lecture that could be regarded as a proper measure for the numerous detailed presentations following on that topic.
Among the presentations were investigations on the reasons of population change, such as food competition among elk and beavers researched by Glynnis Hood, assistant professor at the University of Alberta, Canada:
Caused by overpopulation elk chewed down tree saplings knee high in Elk Island Park Alberta, Canada. On the contrary, according to Hood “beaver turn down a vertical forest into a horizontal” by felling trees in order to forage on leaves and twigs. It were the beavers smart enough to adapt their foraging behavior, given array of forage species, “which potentially buffers the effects of competition between elk, deer and beaver.”
Other topics of the first lecturer day were beaver biology and paleontology at the International Beaver Symposium being performed from Sept. 20 – 23, 2009, in the little eastern European country of Lithuania sited between Baltic Sea and Russian border. Mild temperatures and sunshine made it easy and comfortable to stayand socialize .
On the red pine shaded conference center at a marvelous lakeside in Dubingiai north of Lithuanian capital Vilnius 99 beaver enthusiasts of almost scientific background from all over Europe were joined by 6 leading North American beaver specialists, among them Peter Busher and Skip Lisle.
More to come!
Best
Alex Hiller
