Water vole latrines

[vole-woman]

I've just been pondering water vole latrines, and what I realised I didn't know was how many latrines a female makes. Is it just the two, one at each end of her territory? Or is the whole territory length marked? My observations in the field suggest the latter, otherwise some of my voles have very short territories, but then it's pretty lush feeding round there so maybe that's the case.

Any thoughts?

[Dogghound]

It is a complex subject . Simply put female water voles will mark the edge of a territory but also around the nest, within the burrows, and at key areas where they regularly go into the water or leave it. These latrine sites start to be established around late March (around here, maybe earlier further south), when females start to disperse to breed. So into late April/May all the females in the colony should have marked territories. These are usually highly guarded against other females, however in some colonies i.e. ones which have a very high population density, colonies tend to be quite loose with some overlap and some tolerance of neighbours. Males have larger territories but still deposit latrines similar to the females. Water voles also scent mark at latrine sites from their flank glands which helps strengthen their ownership of the territory (both sexes do this). So your thoughts are correct. The territory size is linked to food availability and colony size. You can work out territories with a little practice, I find mapping and plotting the latrines sites on the watercourse can help. Males are around 100-140m in length, females smaller about 60-80m.

[vole-woman]

"colonies tend to be quite loose with some overlap and some tolerance of neighbours"

- Last night I watched three adult water voles feeding quite close to each other - maybe three or four feet apart.

"Males have larger territories but still deposit latrines similar to the females."

- I didn't know this! I always thought it was just the ladies who set up latrines and trampled them.

"Males are around 100-140m in length, females smaller about 60-80m." -

You mean the individual droppings? I recorded on my blog this morning that some droppings I'd found were quite a bit longer than others, sort of liquorice torpedo shaped rather than tic tac.

So basically there will be latrines all the way along a territory, is that right? Do they make especially large ones at the boundaries? Is there any way to tell a w-v boundary?

[Dogghound]

Originally Posted by vole-woman

"colonies tend to be quite loose with some overlap and some tolerance of neighbours"

- Last night I watched three adult water voles feeding quite close to each other - maybe three or four feet apart.

Interesting this could either be an area between territories, a result of the above (large colony), or they are mature young from an earlier litter. In which case especially females may remain in their mothers territory all year as long as they are not breeding.

Originally Posted by vole-woman

"Males have larger territories but still deposit latrines similar to the females."

- I didn't know this! I always thought it was just the ladies who set up latrines and trampled them.

Yes males have to defend their territory and the breeding females within it from other males so do this in a similar way to the females.

Originally Posted by vole-woman

"Males are around 100-140m in length, females smaller about 60-80m." -
You mean the individual droppings? I recorded on my blog this morning that some droppings I'd found were quite a bit longer than others, sort of liquorice torpedo shaped rather than tic tac.

Sorry this is m for metres and is for the overall territory size for each sex, territories stretch along the watercourse and about 2 metres away from the banks. Dropping size can vary with individuals depending on sex or diet (influenced largely by time of year). Male droppings are probably slightly larger than females.

Originally Posted by vole-woman

So basically there will be latrines all the way along a territory, is that right? Do they make especially large ones at the boundaries? Is there any way to tell a w-v boundary?

Yes latrines will be scattered throughout the territory. I have not noticed particularly large latrines at boundary edges, although you often get two latrines close to each other at the boundary edge. If you map a site, draw on the burrow, feeding signs and latrines, entrance/exit points such as rafts, the territorial ones then can become quite clear.

This document highlights some ways of estimating population size by looking at numbers of latrine sites. http://www.snh.org.uk/pdfs/publicati...s/F99AC320.pdf

However it can be more awkard to specifically seperate individual territories due to the issues of overlap and which latrines are at the edge of the territory or which are in the territory. Also remember that you should consider the opposite bank as a seperate territory if the watercourse is over 3m wide, on large still waters it can become more complicated.

[vole-woman]

Thanks. Lots there to mull over.

So when I see water voles fighting, is it likely to be males rather than females or do they both go in for a bit of boxing?

[Dogghound]

The boxing occurs in both sexes, but females dont often resort to it, as they often beat their tail or show and chomp on their teeth before it gets physical. In males the boxing can get quite intense, ive been close to two and they didnt seem to even notice me being there.

If you need any more help on colony size estimates etc let me know, although I usually do it by mapping. In most cases just to show presence or absence at a site and come up with mitigation strategies.

[vole-woman]

Thanks a lot. I've been looking at the Scottish document, but my maths isn't up to understanding a lot of it. I don't even have an O level in biology, so I struggle with these things sometimes. I think I get the gist on latrines, though.

[Dogghound]

I guess as a very rough way of doing it you could divide the banks into 100m strips and if signs are present you could say 1 male, 2 females and their young (maybe average of 3 to 4 litters with an average of 5-6 young) per 100metres and work it out like that?

[vole-woman]

Will ponder. Thanks.

[vole-woman]

I should add: I saw a latrine on a polystyrene tile float down the stream and lodge a hundred yards away. That's got to confuse matters, surely?