Ed
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Hi Russ,
snip "If you take a look at their historical range, I don't think it's hard to conclude that collecting (either scientific or by hobbiest) was not the common denominator leading to their current status. Habitat degredation (siltation, inpoundment, poor water quality) has to be the leading factor by far."endsnip
I think if you read the literature this is well supported however in waterways that have not been hit with habitat degredation the populations are in most areas still declining. At this time, the only real link they have to the declines is the collecting out of those areas.
snip "And in good habitat I'm leary of "population surveys". Here someone goes in on a single day or two and tips rocks for the afternoon. There is so little we know about their seasonal dispursal, especially of larvae and juveniles."endsnip
The adults have little seasonal dispersal except for short mating migrations during the breeding season. Studies have found the same animal literally under the same rocks at the same times of the year for multiple years in a row outside of the breeding season. (I suggest reading The hellbenders: North American "Giant Salamanders" for the data, 1973, Milwaukee Public Museum Press). There are population surveys on hellbender that have been continous year in and year out for decades so we know pretty well what the adults do. The problem with the larval and small juveniles is that they move down into the gravel beds and to study them would at this time would require invasive techniques which are not enviromentally acceptable (for example excavating and sifting entire stream beds to determine where the larva are in the bed... which would destroy the habitat of the adults).
snip " I concider these less than antidotal. I read an article a while back that claimed "collectors" had wiped out P. petraeus at the type locality, based on a single visit by an undergrad who failed to find one. Collectors?? Based on what data. Funny, a couple of years ago I saw 300+ in an afternoon just a few hundred yards away, but under the right conditions."endsnip
Russ, a few hundred yards away may also no longer be the type locality with this species.. as the type locality if I remember correctly is a cave mouth.
snip "And what about the habitat on private property that is never accessed for assessment, in some states that may make up the majority of good habitat left. Keep in mind that in the east, unlike the west, a lot of the stream habitat in the national forests actually runs through private property. Now I will concur that they have been extirpated in much of their former range or restricted in either good habitat or currently degrading habitat and that they do need management, but lets not point the finger. When you read any paper that concerns population status, you REALLY have to read it. "endsnip
With respect the population referenced in the paper. (C. a. bishopi) the section of habitat that was under study.. was
1) under study for multiple years (starting well prior to 1973 and continuing through several decades (and I believe is still under study today) at multiple time of the year
2) was intesively surveyed for over 5 miles through both public and private property
3) changes in the habitat and population were well documented
snip "The unfortunate thing is that there has been no consorted effort on the part of private collectors to breed benders. Those who currently have them really need to get together and work towards a common goal."endsnip
Not too many people have the space to set up a raceway in thier home or basement....
Ed
snip "If you take a look at their historical range, I don't think it's hard to conclude that collecting (either scientific or by hobbiest) was not the common denominator leading to their current status. Habitat degredation (siltation, inpoundment, poor water quality) has to be the leading factor by far."endsnip
I think if you read the literature this is well supported however in waterways that have not been hit with habitat degredation the populations are in most areas still declining. At this time, the only real link they have to the declines is the collecting out of those areas.
snip "And in good habitat I'm leary of "population surveys". Here someone goes in on a single day or two and tips rocks for the afternoon. There is so little we know about their seasonal dispursal, especially of larvae and juveniles."endsnip
The adults have little seasonal dispersal except for short mating migrations during the breeding season. Studies have found the same animal literally under the same rocks at the same times of the year for multiple years in a row outside of the breeding season. (I suggest reading The hellbenders: North American "Giant Salamanders" for the data, 1973, Milwaukee Public Museum Press). There are population surveys on hellbender that have been continous year in and year out for decades so we know pretty well what the adults do. The problem with the larval and small juveniles is that they move down into the gravel beds and to study them would at this time would require invasive techniques which are not enviromentally acceptable (for example excavating and sifting entire stream beds to determine where the larva are in the bed... which would destroy the habitat of the adults).
snip " I concider these less than antidotal. I read an article a while back that claimed "collectors" had wiped out P. petraeus at the type locality, based on a single visit by an undergrad who failed to find one. Collectors?? Based on what data. Funny, a couple of years ago I saw 300+ in an afternoon just a few hundred yards away, but under the right conditions."endsnip
Russ, a few hundred yards away may also no longer be the type locality with this species.. as the type locality if I remember correctly is a cave mouth.
snip "And what about the habitat on private property that is never accessed for assessment, in some states that may make up the majority of good habitat left. Keep in mind that in the east, unlike the west, a lot of the stream habitat in the national forests actually runs through private property. Now I will concur that they have been extirpated in much of their former range or restricted in either good habitat or currently degrading habitat and that they do need management, but lets not point the finger. When you read any paper that concerns population status, you REALLY have to read it. "endsnip
With respect the population referenced in the paper. (C. a. bishopi) the section of habitat that was under study.. was
1) under study for multiple years (starting well prior to 1973 and continuing through several decades (and I believe is still under study today) at multiple time of the year
2) was intesively surveyed for over 5 miles through both public and private property
3) changes in the habitat and population were well documented
snip "The unfortunate thing is that there has been no consorted effort on the part of private collectors to breed benders. Those who currently have them really need to get together and work towards a common goal."endsnip
Not too many people have the space to set up a raceway in thier home or basement....
Ed