Amphibian terrestrial habitat

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   Answers on a postcard please: is there any data on the amount (Ha) of terrestrial habitat required by amphibians during their terrestrial phase?  

The context of the question is that we are trying to set criteria by which local sites (SINCs) can be designated for amphibians.  Selecting eligible ponds is relatively straightforward, but determining the extent of terrestrial habitat to be designated around them is a bit harder.  We are aware of the potential dispersal distances from ponds, but it's hard to justify designating all the habitat within say a 1 Km radius (i.e. 314 Ha)!!

Whilst we realise that an estimate of the overall habitat requirement for a population will depend on the size of that population, we need criteria which do not depend upon detailed population estimates - not all LA's have the capacity to do this.  The current proposal is to say that a minimum of 0.5 ha of suitable habitat associated with a pond (or pond complex) be designated, but we need a maximum limit as well.

We will probably take the maximum to be the extent of the management unit i.e up to a hard boundary which marks the limit of suitable habitat.

Edited by Matt Harris

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Matt Harris Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 03 Jun 2003 Location: United Kingdom Status: Offline Points: 233	Post Options Post Reply Quote Matt Harris Report Post Thanks(0) Quote Reply Topic: Amphibian terrestrial habitat Posted: 11 Mar 2004 at 3:43pm
	Answers on a postcard please: is there any data on the amount (Ha) of terrestrial habitat required by amphibians during their terrestrial phase? The context of the question is that we are trying to set criteria by which local sites (SINCs) can be designated for amphibians. Selecting eligible ponds is relatively straightforward, but determining the extent of terrestrial habitat to be designated around them is a bit harder. We are aware of the potential dispersal distances from ponds, but it's hard to justify designating all the habitat within say a 1 Km radius (i.e. 314 Ha)!! Whilst we realise that an estimate of the overall habitat requirement for a population will depend on the size of that population, we need criteria which do not depend upon detailed population estimates - not all LA's have the capacity to do this. The current proposal is to say that a minimum of 0.5 ha of suitable habitat associated with a pond (or pond complex) be designated, but we need a maximum limit as well. We will probably take the maximum to be the extent of the management unit i.e up to a hard boundary which marks the limit of suitable habitat. Edited by Matt Harris

calumma Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 27 Jun 2003 Location: United Kingdom Status: Offline Points: 375	Post Options Post Reply Quote calumma Report Post Thanks(0) Quote Reply Posted: 11 Mar 2004 at 9:42pm
	Some published work details an appraisal of this very thing for American salamanders. Unfortunately I'm flat out surveying at the moment and don't have time to dig out the reference. ANyone else have it to hand? Newts are most likely to disperse up to ~250 m from breeding ponds (providing there is sufficient suitable habitat). Indeed you could consider ponds that lie within 250 m of each other to represent the same sub-population. Individuals can disperse further, radio tracking work in Europe suggests more than 1 km. EN have suggested that 500 m may be a reasonable area in which to conduct development based surveys. I recommend that you look at protecting habitat within 250 m, but with a proviso that terrestrial habitat at greater distances could still be occupied. Frogs and toads can disperse further, several km in the case of toads.
	Lee Brady Kent Herpetofauna Recorder \| Independent Ecological Consultant Email

Matt Harris Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 03 Jun 2003 Location: United Kingdom Status: Offline Points: 233	Post Options Post Reply Quote Matt Harris Report Post Thanks(0) Quote Reply Posted: 12 Mar 2004 at 8:48am
	Thanks Lee. The nub of the problem is whether to define the terrestrial habitat in terms of a radius from the pond based on dispersal distances or to have a hectareage based on population size. Either way, we to have criteria which are practical to apply and will stand up to scrutiny in court if it came to it.

calumma Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 27 Jun 2003 Location: United Kingdom Status: Offline Points: 375	Post Options Post Reply Quote calumma Report Post Thanks(0) Quote Reply Posted: 12 Mar 2004 at 5:02pm
	No reliable estimates exist that relate newt population size to area of terrestrial habitat. Some time ago EN had a fag packet calculation of 250 newts per Ha (in good habitat), but this was pure guesswork and there is no credible scientific data to back it up.
	Lee Brady Kent Herpetofauna Recorder \| Independent Ecological Consultant Email

Martin Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 23 Feb 2003 Location: United Kingdom Status: Offline Points: 87	Post Options Post Reply Quote Martin Report Post Thanks(0) Quote Reply Posted: 13 Mar 2004 at 8:46am
	Tricky one! Some considerations that come to my mind would be the degredation of the habitat post development due to increased activity and usage. Some allowance should be made for full movement offsite as well as this can be a colony limiting factor in the longer term - they need new blood. There was some good work on this published in a BHS journal a few years ago. I'll see if I can find it but as I borrow the journals I actually doubt that it'll easily come to hand. Martin.