Tag Archives: roe deer

Diapause and Diminishing Diversity

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!

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Serendipity II – The charismatic cuckoo

I don’t recall having seen a cuckoo before, even though I’ve heard their unique call many times. But on my sojourn over to Wicken Fen a couple of weeks ago there were lots of them. ‘Lots‘ is a relative term because cuckoos are becoming increasingly scarce, their conservation status is red due to recent declines in the breeding population and in 2000 there were 9.6-19000 breeding pairs in the UK. But on this trip we heard and saw at least 5 and possibly several  more.

Just before I spotted the first cuckoo I glanced across the lake and this was the view:


A pair of shoveler in the foreground, a little egret behind and a roe deer just beyond the reeds

I really like this picture because of the colours of the reeds and the water in the evening sunshine, but also because it contains three interesting species. Apart from rabbits, any wild mammal is exciting to see in this country, so the roe deer was a pleasing encounter. The little egret (Egretta garzetta, Dansk: silkehejre) is a member of the heron family which is now resident in the UK, presumably as a result of climate change. I associate them with warmer places because that’s where I saw them before 2000, but nowadays they’re not particularly uncommon here. And in the forefround are two shoveler (Anas clypeata, Dansk: skeand) which are migrant visitors to the UK, but this pair obviously liked it enough to linger and are still here in the middle of May, long after they would normally have left.

And then there were the cuckoos:


A pair of cuckoo, Cuculus canorus, Dansk: gøg

The cuckoo is an incredible bird and until very recently it was poorly understood. Last year the British Trust for Ornithology (BTO) managed to tag five male cuckoos with tiny satellite tracking devices and found out that they headed to the tropical sub-Saharan rainforests of Cameroon and the Democratic Republic of Congo. The cuckoo arrives back in England from Africa in late March or April and departs in July or August. It leaves earlier than other species because its parasitic breeding strategy removes the need for chick rearing. That means the cuckoo spends a minimum of 8 months a year in Africa so to call it a British bird is, I suppose, less than accurate, even though it breeds here.


The classic hanging wings pose which I always associate with the cuckoo

The tagged birds were all fitted with solar powered devices which transmit location data once every 48hr. The tracking data revealed that all five birds headed south over France and across the Mediterranean before heading down across Africa to Cameroon and DRC. All five made it. One of the birds died in Cameroon and two more died on the way back, but two of the five made it back to East Anglia this year. I believe the BTO plan to tag more birds including females and I’m very keen to see the results of that experiment.

The cuckoo is an iconic bird in the UK and it’s call is very distinctive. The call is generally recognised as a signal that Spring has arrived and there are local traditions around the UK based on the cuckoo. It is said in Worcestershire that the cuckoo is never heard before Tenbury Fair on April 21st or after Pershore Fair on June 26th. The song actually changes in June from the characteristic ‘cuck-coo‘ song to a shortened ‘cuck‘, and there is a rhyme about this:

In April I open my bill
In May I sing night and day
In June I change my tune
In July far far I fly
In August away I must

My Dad remembers a similar rhyme he used to sing when he was a kid in the 1940’s which was essentially the same but with some local Northamptonshire words substituted in.

I’m not quite sure what these two were doing but they were acting as a pair, and every minute or two one of them would dive off into the adjacent reedbeds to return a minute or so later. As I mentioned above, cuckoos are parasites and they could have been looking for nests to parasitise. There breeding strategy is unique, at least as far as I know. They lay their eggs in the nests of one of three other small songbird species: the reed warbler, the meadow pippit and the dunnock. All of these are the size of a sparrow (ish) so are much smaller than the cuckoo which is dove-sized, which I guess guarantees that the cuckoo chick will be much bigger than its ‘siblings’ and it won’t be threatened. The cuckoo chick then ejects the other chicks from the nest to die and the parents assume it is one of their own and feed it until it fledges. I’ve seen film of a cuckoo chick turfing out the other chicks and it’s a remarkable process, and not particularly pleasant to watch!

Despite their unsavoury procreation habits they are spectacular and charismatic birds and I hope the BTO research can find ways to guarantee their continued return here to brighten up the Spring and Summer.

The frozen Fen

The winter frost finally arrived in my corner of Cambridgeshire in the last week and it left the landscape with a thick coating of pure crystalline whiteness. So I was able to indulge my recently discovered fascination with more abstract nature photography:

Ice needles formed on horse hair snagged on barbed wire scattering the sunshine

My trip out to Burwell Fen, east of Cambridge, early last Saturday morning was spectacular as a result of the frosty weather. I set off with my friend, David, around 8am with a view to catching some more sightings of short eared owls, and at that time the temperature was well below freezing. But it was one of those beautiful misty mornings where the mist is thin and lets through lots of light but the density waxed and waned, creating constantly changing, ghostly conditions. Which is lovely to look at but not so good for finding wildlife.

As we approached the Fen, driving out the back of Reach through Tubney Fen (which, incidentally, has had nesting avocet in previous years), roe deer and red-legged partridge were in abundance (no exaggeration!) . I like partridge and I see them quite often around Histon, but I usually flush them before I can get close enough to photograph them, but on this instance the car made a great hide.

Three of a small flock of red-legged partridge absorbing the heat from a huge pile of dung. Splendid birds,  bizarre that people want to shoot them rather than just look at them.

Red-legged partridge (Alectoris rufa, Dansk: rødhøne) were introduced to England from Europe and alas for them they are a game bird.

Roe deer (Capreolus capreolus) were also much in evidence, we counted 43, and at one point on the Fen they were flushed and moved en masse and we counted 31. I don’t think I’ve ever seen that many in one go and it was a terrific sight. We think the four below were part of a family of five, the fifth just out of shot. The big one on the right is the female, the horned one in the middle is the male and the other two are youngsters, the third youngster is the one out of shot.


Four of a family of five roe deerRoe deer tracks with a 2p coin to show the size. They were mixed with muntjac tracks, but could be distinguished by the larger size:

Muntjac deer tracks

Roe deer are native to the UK but muntjac, also known as the barking deer, were introduced from China to Woburn in Befordshire where escapes and releases, and their obvious liking for the Home Counties led to a rapid expansion of their population. I regularly see and hear them in Histon, and the barking sound they make is quite unlike anything likely to be heard in the English countryside.

Whilst scanning for owl, I spotted a stonechat in the grass (Saxicola torquatus, Dansk: Sortstrubet bynkefugl):


Male stonechat

The stonechat is a resident breeder and a migrant to the UK and frequents the kind of scrubby countryside found on Burwell Fen.

Then when the mist lifted and the morning developed into a very cold but very sunny one, the owls appeared, and we had lots of sightings. We chatted to a BBC camera man in the car park who had come to film the short eared owls and he must have captured some good footage by the time he went home.

They are great to watch, they hunt low over the scrub for rodents and regularly get chased up in the air by crows and on one occasion, a kestrel.


Short eared owl

Short eard owls (Asio flammeus, Dansk: mosehornugle) have a small breeding population in the UK, but also migrate here in the winter from northern Europe. I’ve heard that they are here in larger numbers than normal this year due to last year being a good lemming year in Scandinavia. Whatever the reason I’ve heard a number of reports of sizeable groups in Essex, Cambridgeshire and Northamptonshire. They are diurnal and therefore easier to see than most owls and they are very distinctive. The underside is largely white, the winspan is around a metre and the pale brown spot toward the end of the top of the wing is also easy to see and differentiate them. They also have bright yellow eyes which I’ve heard is characteristic of owls which hunt in daylight – but I’ve not found any hard evidence for that.

Lastly, we had several encounters with this group of nine grey partridge, also known as the English partridge (Perdix perdix, Dansk: agerhøne). The numbers of our own partridge have plummeted catastrophically in recent decades, by up to 90%. I see the occasional one around Histon, but it was good to see this group on the Fen.


Six of a group of nine grey partridge

The red/brown head and lack of white face, black eye stripe and white wing markings clearly distinguish the grey from the red-legged partridge. The difference in demeanour was remarkable, the red-legs seemed relatively unfazed by our presence and were easy to see and photograph, but the greys sat tight, very low to the ground, and flew away at the slightest disturbance.

In one trip we saw all the UK partridge species, and lots of short eared owls, and more roe deer than I’ve ever seen before in one go. Well worth the early start on a freezing morning!

All those flocking waders

The Cambridgeshire Fens can be a bleak and windswept part of the world as the winter months descend, and today it was very bleak and very windswept, but it’s a great location for getting out and seeing some exciting and scarce wildlife.


A small flock of lapwing and golden plover over Burwell Fen

For those of you who don’t know the Fens they’re characterised by wide open flatness and big skies. They were originally under water but were drained by Dutch engineers in the 17th and 18th centuries to leave high quality arable land. The soil is extremely rich in organic material which gives the soil the rich black colour evident in the picture above.

I set off there on Saturday with my friend David because there had been a report on the Cambridge Bird Club website of short eared owls (Asio flammeus, Dansk: mosehornugle) in the vicinity. After wending our way through Swaffham Prior and Reach we rocked up at Tubney Fen where we sat in a new National Trust hide overlooking a new pond with new reed beds which had four coots (Aythya fuligula, Dansk: blishøne) and a pair of mute swans (Cygnus olor, Dansk: knopsvane) paddling on it. And no other signs of life whatsoever.

As we watched, the mute swans took off and looped round low right in front of us and landed back on the water. At least one of them landed on the water in the spectacular and graceful way that mute swans do. The other one crash landed on the ground just short of the water and after regaining its equilibrium stood looking highly indignant but managed to retain it’s dignity in a way that only a mute swan could in those circumstances. We hoped it wasn’t injured but it looked to be suffering from little more than damaged pride.

After another five minutes sat in the hide the lack of further activity and the low temperature caused us to move on, and on the way back to the car we spotted eight whooper swans in a field several hundred meters away. The whooper (Cygnus cygnus, Dansk: sangsvane) is a winter migrant to the UK and a very scarce breeder, usually less than ten pairs a year will breed here. It’s a similar size to the mute swan but it’s neck is straighter and the beak is straight with a black tip and pale yellow base. Their breeding territory is in the high Arctic and they migrate south as far as Africa for the winter.


A family unit of eight whooper swans – two adults with white plumage and the charateristic yellow beak and six cygnets with pale grey/white plumage and without the yellow beak

We decided to move on to Burwell Fen from Tubney Fen and on the way we were considerably closer to the swans so we stopped for another look. And as we looked David noticed that a pale brown stripe in an adjacent field was in fact a flock of golden plovers (Pluvialis apricaria, Dansk: hjejle) and lapwings (Vanellus vanellus, Dansk:  vibe). When I was a kid I spent a fair amount of time out and about exploring the countryside and huge flocks of lapwing consisting of hundreds and possibly thousands of birds were a fairly common sight. But their numbers have been dwindling for decades and these days I’m pleased if I see more than twenty. A carrion crow was getting agitated in the tree beyond the plovers because a buzzard (Buteo buteo, Dansk: musvåge) was perched there too, but the crow wouldn’t get too close and the buzzard just sat tight and ignored it. There turned out to be 243 lapwing in this flock and for me that alone justified the trip.


Around 10% of the lapwing in our flock of 243

There were also several hundred golden plover. As we watched another even bigger flock joined them and when they were flushed into the air we could see another flock as big again in the middle distance and beyond that another that was enormous. So we estimated that between these flocks there were several thousand birds. It was a amazing sight.

The flocks of waders eventually settled so we made off further into the Fen, pausing to gaze at a group of roe deer (Capreolus capreolus) relaxing in a field:


These very well camouflaged roe deer didn’t seem at all perturbed by our presence

As we watched the deer, a sparrowhawk (Accipiter nisus, Dansk: spurvehøg) quartered the field and then a peregrine falcon (Falco peregrinus, Dansk: vandrefalk) swooped past car, travelling with the customary haste that species is renowned for.

Arriving eventually at a car park, we continued on foot over a bridge where several kestrels (Falco tinnunculus, Dansk: tårnfalk) were quartering all the fields around and almost immediately spotted a short eared owl. It was perched on a fence post in the middle of the adjacent field and I initially mistook it for a little owl because I was looking at it from front-on and I could only see the top half, but when we saw it through David’s spotting scope we could clearly see it was of the short eared variety.

Short eared owl hunting rodents the easy way, not wasting any energy

As a result of the inclement weather, low light and strong wind, and only having a 300mm lens I couldn’t get any good photographs, but it’s unmistakeably a short eared owl, so I’m happy.

We saw various small songbirds such as chaffinch (Fringilla coelebs,  Dansk: bogfinke) and goldfinch (Carduelis carduelis, Dansk: stillits), five bird of prey species, whooper swans, and countless thousands of golden plover and lapwing. So despite the cold it was fine way to spend a Saturday morning.