Capreolus capreolus, aka the roe deer, is native to the UK and can be seen in good numbers in the Fens. During an evening stroll there in July I encountered several. As well as being delightful to look at they have some interesting reproductive biochemistry. The roe deer rut takes place in July and August but the fawns are not born until the following May or June, nearly a year after the rut. The length of roe deer gestation had puzzled zoologists for a very long time and then they discovered that the roe undergoes delayed implantation, or ’embryonic diapause‘.
A roe deer peering at me as I meandered around Wicken Fen
But that wasn’t the end of the story. It was assumed that hormonal messages from the mother would tell the dormant fertilised egg, or ‘blastocyst‘ when it should implant into the endometrial layer of the uterus, but the search for the maternal hormonal trigger which has been observed in other mammals drew a blank. It transpires the trigger is a novel mechanism whereby the embryo, which at that stage consists of around 30 cells and has its own internal timer mechanism, secretes a messenger molecule called ‘rdPAG’ (roe deer Pregnancy Associated Glycoprotein) which precipitates a maternal hormone cascade of oestrogens that initiates the second stage of the pregnancy with implantation of the embryo. This is a remarkable piece of biology because it is orchestrated by the embryo, not the mother, and ensures the fawn is born during the favourable weather conditions of the summer thereby guaranteeing it sufficient time to prepare for the winter.
A visit to Wicken Fen always provides multiple unique photographic opportunities such as this pair of grey herons whose paths crossed, almost on a collision course:
Wicken Fen was mentioned in a BBC News article a couple of days ago about the importance of the Fens as a wildlife haven. The article is about a study into the biodiversity of fenland since 1670. Apparently, since the start of the study period 100 species of birds, bees and butterflies have been lost from the Fens and in total 504(!) rare species have not been recorded there in the last 25 years. A moments comtemplation on that rate of biodiversity loss is terrifying, and the implications of it even more so. It boggles my mind that the political decision makers, who are aware of all the environmental devastation, don’t appear to give a damn about it. Or at least not enough to want to do anything about it.
Despite that the Fens are still a very important refuge for endangered species, which I can vouch for based on my observations made whilst wandering around Wicken. The Fens are much maligned but are a unique and important haven for many species of all kinds of wildlife.
In order to manage and maintain the flora of the Fen which then provides shelter and sustenance for a multitude of other species, horses and cattle have been installed there, one of which is this magnificent chap:
This image doesn’t really do him justice, he is absolutely enormous – like a minibus on legs!
The Naturephile 