We are coming up to the time when deer does give birth to their fawns (Fr. faons) and I thought it was time for a bit of public education. The law in France is that your dog must be on a lead if you are walking through forest*, vineyards, open country whether cultivated or not, orchards, woods, marshland, the banks of water courses, dams (Fr. étangs) and lakes between 15 April and 30 June. There is a fine of 750 euros if you are caught and convicted.
Young fawns are left hidden alone in the grass or undergrowth for many hours during the day, from the time they are newborn to a few weeks old. Meanwhile their mothers go off some distance away so predators are not alerted to the presence of the fawn. The does browse on the new spring vegetation that gives them the level of nutrition they need. It is important for them to keep up the supply of milk that the fawns require to thrive.
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A Roe Deer fawn in our orchard several years ago.
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Newborn fawns are very small -- not much bigger than a rabbit -- so they can remain hidden quite easily. Fawns are famous for remaining completely still no matter how close you get. If you stumble across one, please leave it alone and move away as quickly and quietly as possible.
If you are walking through
lightly wooded prairie at this time of year, please keep dogs on leads.
The fawns will sit tight until you are within about half a metre of
them. Startling them and causing them to run uses up their valuable energy and
significantly reduces their chances of survival. Under no circumstances
touch them or speak to them (the human voice, no matter how soothing a
tone you think you are using, is extremely frightening to them).
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A Roe Deer fawn hidden in long grass in the middle of a prairie in Vienne.
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Roe Deer Capreolus capreolus (Fr. chevreuil) numbers in France are increasing, but the rate of increase is
slowing. Fewer fawns are being born and fewer are surviving to
adulthood. Careful monitoring of the does parturition dates reveals that
they haven't significantly changed from year to year, even though the
date of leaf burst in the forest is now earlier by about a fortnight
compared to 35 years ago when the monitoring started.
This means that the deer are no longer giving birth to coincide with
peak availability of food for the mothers, which impacts on their milk
supply. Roe Deer are browsers, feeding mainly on coppiced trees, and
rely on the new shoots in their forest habitat. Fawns aren't gaining
weight and strength as quickly as they should and as a consequence are
more vulnerable to predators, disturbance and other stresses. The likely cause of death for most fawns is lack of food,
as the deer locally in the Touraine are not subjected to pressure by hunters or
predators.
Scientists have concluded that Roe Deer ovulation and conception,
and therefore parturition, is linked to day length, not temperature, and
that they are likely to be climate change losers in the long run. This
is exacerbated because does all tend to give birth around the same time
(May), and those few which give birth early will not be sufficient to
cause an evolutionary change. All the fawns are vulnerable at the same
time, which means that extreme weather conditions, for example, could
wipe out an entire generation. Other studies have indicated that
Greenland caribou (reindeer) have similar issues, but that Red Deer are
adapting and giving birth earlier (interestingly, by reducing gestation
periods).
The average springtime (April - June) temperatures
have increased year on year and are now nearly 1.5°C higher than when monitoring these deer began. This rise in temperature is causing trees in particular to
respond by bursting into leaf earlier. Thirty-five years ago Roe Deer gave birth exactly when the tender green
shoots of many plants were available, full of nutrition before their
energy goes into flowering and seed production. The mismatch between
birth dates and peak vegetative flush has increased by about half a day a
year. A fawn born on or before 12 May has a 50% chance of surviving to winter and adulthood.
After that date, survival rates plummet, and one born at the end of May only has a 24% chance of
surviving. (It should be noted that the number of days mismatch between
birth date and peak vegetative flush in any given year is a better
predictor of survival rate than birth date per se.) Older, heavier does
tend to give birth earlier, so there is some natural selection
mitigating the effects of climate change, but probably not enough in the
long term, and the tendency to give birth earlier is not strongly
heritable.
*Technically the dog can be off the leash if you are on one of the marked 'allées de forestieres' but the minute your dog leaves the track and heads into the undergrowth you are breaking the law.
The National Office for Forests (ONF) is increasingly fed up with dog owners who can't control their dogs and don't understand that their pets are causing distress and even death to wild ground nesting birds, and to wild deer who have left their fawns cached.
