Science Forums 2

[freeztar]

Originally Posted by Cedars

Ah yes, the scientific data which is referred to in a legal filing. Not like lawyers presenting their case gloss over inconvient portions of scientific data.

The lead author is Shaye Wolf who has a PhD in Ecology and Evolutionary Biology.

"Because juvenile dispersal occurs within months of birth, juveniles at low-altitude sites in the Sierra Nevada generally disperse during the summer, when temperatures are high, leading to low dispersal success (Smith 1974a). Following a dry winter or early spring, the period for gathering hay may end before juveniles disperse, greatly reducing success of dispersing juveniles (Smith 1974a)."

*interestingly, this area has been experiencing dryer conditions. Combine that with the data indicating the planning of the resevoir system all over the west was calculated on conditions present during an unusually wet period leading to some of the water issues we are seeing.

"Peacock (1997) found that an average of 34% of the adults in a high elevation Sierra Nevada population (3,170 m, 10,398 ft) were replaced each winter by immigrants, 5% of which made long-distance dispersals of 2 km, 67.5% of which made short or intermediate dispersals less than 2 km, and 27.5% of which recruited from within the population."

"At Bodie, eleven habitat islands occupied in 1972 were unoccupied in 1977, and eight sites unoccupied in 1972 were occupied in 1977 (Smith 1980). Smith (1980) also found that 53% of 77 islands changed in territory saturation over the five years, and higher extinction and lower recolonization rates were associated with small island size and increased isolation"

Ok, but what about long term trends.

Another article in WWF added small tidbits to the bigger picture of these isolated pockets of rabbit relatives not mentioned in the legal briefing. Road construction and increased human populations in these pika areas as having an impact on their populations (however they did not list enough data to conclude what percentage of pika decline was related to this factor, but it was noted).

I wouldn't doubt that these aspects would be factors in the decline, but without numbers, it's impossible to quantify their contributions.

The ABCnews portion of the Pika story adds more suspense as Chris Ray of the University of Colorado states they are looking into a possible viral infection sweeping thru some of these pockets of pikas. Would explain the half eaten winter supplies in some of these now abandoned pika locations.

I don't know anything about this, but again, without data it's impossible to quantify.

There is also the lack of historical data. Piece after piece referred to 1933, then nothing until the late 50s, then some bits from the 70s and now suddenly, its a tragedy unfolding. They are members of the rabbit family, a family with well documented high / low population cycles.

The paragraph I previously quoted had a study by Beever analyzing data from 1950-2003.

It is well known genetically isolated creatures have a greater potential for increase mortality rates with slight shifts in habitat. The introduction of a disease can push an animal over the edge when it evolves into too narrow of a niche.

Agreed, yet it still remains that the scientist I previously quoted was pointing towards increased temps as the predominant reason for the shift in habitat.

Perhaps we should break this off into another thread?