Giladis wrote:That looks mindbogling.
Have you encountered fault lines within the population or did the creatures freely move between the ponds?
My study wasn't designed to look at free movement between ponds. As a rule, this species may disperse in its juvenile phase but once it begins breeding they have strong pond fidelity. On this site, with such a high density of ponds, I suspect there is some movement between them. One of my model assumptions is that, while newts are allowed to move freely between ponds, there should be no
net migration. I was never able to quite bottom out whether that assumption was valid or not, as is often the case in ecological studies unfortunately. I could argue the case though...
What I did find though was a (loose) suggestion that ponds in the more isolated parts of the reserve still host as many newts as their counterparts in the main reserve, which suggests that the isolated areas are still sufficiently large and high quality (and quite possibly sufficiently well connected to the main area) to sustain their resident newts. It might be interesting to explore this at the genetic level, although that's very much not my area of expertise. My analysis also showed that the grassland areas were better populated than the scrubland areas...but the reasons for this aren't immediately apparent to me, because the species is quite a generalist. As the areas in questions are blocks rather than in a stratified matrix I suspect there might be something underlying this, like perhaps more hibernacula within the grassland areas.
Prince of Spires wrote:It looks amazing. Never knew such a place existed. It looks like great hiking ground
You do look a bit cold in that last photograph though...
Any interesting findings in your study?
Rod
Haha, yeah - i really enjoyed working on that site. I've changed jobs to something more desk based (still reserves management, but more, well, management now...). Combined with all my free time going into study (or procrastination), I've been putting on weight over the past couple of years, so I got myself a fitbit to scare myself out of being so sedentary. It's really shocking - on a 'reserves day' I can easily exceed the target 10K footsteps/5K distance, on a day with a site visit I can get 1/3 - 1/2 of the target at work, but on an office day I might not even hit 1000 footsteps...which is astonishing. By contrast, on that reserve I'd be on-site most (work) days, charging up and down the hills, having a whale of a time. Definitely a good place for walkers, although sadly not open access to the public.
That winter photo is from one of my first sessions when I started the job. The guy who took it only came along to that one session but curiously enough 3 years later when my wife was scoping out professional photographers, he was the one she chose for our wedding. (Incidentally, top bloke, excellent skills, couldn't recommend him highly enough).
Lots of interesting finds from the study - the ones I gave Giladis above are some of the shakiest (he would have to ask a question which my study doesn't easily address, wouldn't he
).
Main findings, in no particular order, were:
1) quantification of the negative effect fish have at different abundances and the positive effect of pond size on great crested newt (GCN) populations; these two were quite interesting because they broadly agree built build on the existing literature on the topic
2) detection rates vary both within season (i.e. from start of April until start of June) - which we pretty much already knew, but also between seasons (i.e. between years)...and this has big implications for monitoring populations, because if the proportion of newts which you're spotting is not constant between years, how can you tell if any changes in counts represent a true change in population or just detection error? (The answer there lies in using some sort of statistical modelling, in my case occupancy models, to estimate the detection rate: if you know both the detection rate and the observed count, it's basically just a case of re-arranging the formula to find x, the total population). The big implication of this is that the standard method - where we do a bunch of surveys, discard all but one, and compare the peak count from each year - is suspect, because it assumes that the vagaries in detection rates will even out over several surveys so will be consistent over peak counts, but this probably is not the case.
3) Having calculated the population on my reserve, I was able to compare it to the historical number which were translocated there in teh 90's, and I showed a significant drop. (Many caveats here are needed, because you'd be a very brave person to try to suggest a trend from just two datapoints (1990s vs now). However, my method does present a technique for assessing the success or otherwise of the translocation, as well as a method for monitoring the population.
4) I was able to show that the difference in population between then and now was equivalent to the amount of extra newts you would expect there to be i the ponds which currently have fish in did not. This suggests that if the decline is indeed real, and not just an aberrant year when I surveyed, that the translocation was broadly successful other than controlling the spread of fish.
5) I was also able to show that if you could completely eradicate hte fish from the site, you would expect the population to bounce back to baseline levels, but if you could not
completely eradicate it then you'd make no significant difference to the GCN population, despite great expense in trying, so the implication is that fish management needs to be an all or nothing approach...and I therefore advocate for the use of piscicide in this context, but currently it is not permitted for conservation purposes. (My position is relatively controversial here, although I'm basing it on very sound principles and case studies).
They're probably the best bits...seems strange it took around 200 pages and 4 years to say just that