Moorhens and More

Kingdom: Animalia

Family: Rallidae

Species: Gallinula chloropus

The common moorhen, also known as the swamp chicken (not a nice nickname really is it?), is a species of bird found widely across the Old World: the parts of the world known to Europeans before the discovery of the Americas, including Europe, Asia and Africa. Although they are birds, they are better at swimming and walking than they are flying, and are often seen swimming bobbing their heads back and forth.

Moorhens are found in well-vegetated marshes, ponds and other wetlands. I found a few when walking along a river somewhere on the UEA campus behind the lake... However, I am not sure exactly where this is as I did get a bit lost! The moorhen is distinctly recognisable because of its dark plumage with a white under tail and stripes on the flanks, yellow legs and red bill with a yellow tip. Younger moorhens are brown and lack the red frontal shield. They grow to 12-15 inches with a wingspan of just under 2 feet. Their feet are not webbed - they have long chicken-like toes (hence the nickname) which enable them to walk on top of the floating vegetation and the mud.

They consume a variety of vegetables and small aquatic animals, foraging either in the water or on land. They are quite secretive, although this one was tame enough to let me close enough to get some pics, even if they are a little blurry. This may be because I took these before breeding season had started - this takes place from mid-March to mid-May in the Northern hemisphere, and usually in lowland areas in the UK in central and eastern England, which the UEA campus is a clear example of!

During the breeding season the birds can get very territorial. The male moorhen courts the female by bringing her water weeds and fanning out his tail. They form a monogamous pair and build their nests on the ground in dense vegetation, in a bowl shape and made of twigs, cattail, grass and sedges. Usually the male gathers the twigs and the female builds the nest among vegetation in the water. 

About 8 eggs are laid per female early on in the season, at a rate of about 1 egg per day, although this may be slightly less later on. The eggs are smooth and glossy, of a greyish-white to green colour with reddish-brown or grey markings, measuring about 43mm by 31mm. Incubation lasts about 3 weeks and is done by both parents, showing the high parental investment typical of birds. Young moorhens are precocial, and can therefore leave the nest and feed themselves within a few days of birth. They then fledge after 40-50 days. If the young fee threatened, they cling to their parents' body and the adults carry them, flying away to safety. 

Moorhens are often confused with coots, but although coots are similar, they have a white beak, and have no red mark. This can be remembered by thinking R is for red, and there are no "R"s in coot! Another way is to think CO reminds you of a cold and white frost, or OO reminds you of snowballs which are white - these can be related to the white beak!

The moorhen population began declining in the 1970s and 80s but has recovered since. This was thought to be because of a result of reduced clutch size caused by the spread of the American mink, which predates the birds' nests along waterways. The moorhen is considered now to be a species of Least Concern by the IUCN, so we don't need to be bidding farewell to the moorhens on our waterways for hopefully a very long time!

Field Trip - Ancient Woodlands and Dog's Mercury

Ancient woodlands provide a rich and unique community of plants and animals, as they have been around long enough for the ecosystems to develop into complex and irreplacable habitats. Plants and animals depend on the stable habitat the woodland provides due to the relatively undisturbed soils. Ancient woodland is any woodland that has been around since 1600AD (1750AD in Scotland) or earlier; some woodland in the UK has been around since the last Ice Age approximately 10,000 years ago! 1600 was when planting of new woodland became more common and so woodland established before this time is likely to have developed naturally.

They also indicate to us signs of history that allow us to trace backwards throughout the woodland's lifetime, giving them cultural value as well as conservational. Medieval boundary banks, old coppice stools - all tell a story about an England very different to the one we now know. Ancient woodland can be characterised as 

Semi-natural woodland: Mainly made up of trees and shrubs native to the site, arising from natural generation in most cases.

or

Plantations on ancient woodland sites: Areas of ancient woodland where the former native tree cover has been felled and replaced by planted trees, typically not native to the area. Planted Ancient Woodland Sites (PAWS) can be restored to give rise to Restored Native Woodland on Ancient Sites (RNWAS).

Foxley Wood: Photo by Richard Osbourne

Foxley Wood is Norfolk's last remaining ancient woodland, and it contains a number of ancient woodland indicator species (AWI's), including:

Wood anemone (Anemone nemorosa)

Wood sorrel (Oxalis acetosella)

Honeysuckle (Lonicera peliclymenum)

Common dog violet (Viola riviniana)

Dog's Mercury (Mercurialis perennis): A case study

Kingdom: Plantae

Family: Euphorbiaceae

Species: Mercurialis perennis

Dog Mercury: Photos from naturessecretlarder.co.uk

The name 'dog's mercury' is said to originate from the messenger of the gods, Mercury, who is the one to discover it. 'Perennis' is used to distinguish it from the 'annua' species, which was used as a diuretic (to increase urine production) and as a purgative (to give a laxative effect). 'Dog's' is a term used to describe a plant with no medicinal uses (in the sense of 'false' or 'bad', as even though recently it has been harvested to use as a laxative this is discouraged by herbalists due to its cumulative effect.

Dog's mercury can quickly colonise and spread throughout an area by using underground rhizomes. The plant favours alkaline soils and is found in abundance in suitable habitats in limestone regions. It is present in neutral soils too, but not acidic soil. This can lead to crowding out of other, rarer, species such as Fly orchids, or even Ash seedlings, which we saw are already under threat due to Ash dieback diseases, present on some of the trees in Foxley Wood. The plant is characterised by its spear-shaped, toothed fresh green leaves, upright set, small, greenish flowers, and a foul and rotten smell that it produces. By coppicing at Foxley Wood, the woodland floor is exposed to sunlight which helps other flowers and plants to thrive and thus keeping others that spread easily under control: preventing the Dog's Mercury takeover. In other areas of East Anglia where coppicing as ceased, Dog's Mercury has been observed to be increasing in abundance.

Dog's mercury is highly poisonous, due to the combination of methyl amine  trimethylamine, a volatile oil and saonins. It is diuretic purgative, and emetic, meaning it causes diarrhoea and vomiting after consumption. Larger doses also lead to lethargy, jaundice, painful urination, gastric and kidney inflammation, inflammation of the cheeks and jaw, and potentially a coma which leads to death. Yep, that's enough to keep me well away.

The leaves often poison sheep or cattle, but no incident of severe human poisoning has been reported since the 1980s when a couple ate the plant after boiling it, thinking it to be a green vegetable: they recovered within 2 days. The first case of human poisoning was reported in 1693, when a family of five ate it and one of the children died. For some reason though, some people still think it's worth a try! One woman wrote on 09/02/17 when commenting on a blog about Dog's Mercury: "I picked some dog mercury and ate it on a salad. I thought I'd read a small amount was ok to eat... was enough to cause my lips, mouth and throat to burn. This was followed by a feeling of shaky weakness and a need for the toilet". 

Why you would want to risk it I do not know, but I guess it goes to show that you should double check if something is safe before you try eating it! All in all, this is a pretty nasty plant from anyone's point of view. So by all means, look out for it the next time you think you might be in an ancient woodland, as well as the other AWI's, but don't get too close!

Field Trip - Sampling leaf miners

As part of our Issues and Approaches in Ecology module we went on an on-campus field trip, and one of the things we did was sampling leaf miners on holly bushes (Ilex aquifolium). A leaf miner is the larva laid on a leaf by an insect, which lives within the leaf and eats the plant tissue. Insects which do this include moths (Lepidoptera) and flies (Diptera). This protects the larva from many predators, and provides them with a source of food. The miner leaves a discoloured blotch on the leaf, which is usually green with some brown marks within, as below:

Photo by David Fenwick

This pest has little impact on the health of the holly bush, and is difficult to control as insecticides are relatively ineffective due to the thick, glossy protective layer the surface of the holly leaf provides. On other plants which are less well protected, however, they can reduce the economical value of a crop, causing problems for farmers, so in this context control of leaf miners is more of a pressing issue.

The task we were set seemed relatively simple, to conduct an experiment to estimate the population of holly bushes and the number of these affected by leaf miners. We began designing our experiment, and in our group of 5 we found that we could easily identify new growths from the last season as it leaves a scar on the branch. Therefore we could estimate the number of leaf miners left in the last growing season, between May and June.

We conducted our survey as follows. We divided the area of woodland we had been given into five separate areas by pacing out five paces along the path, and five paces away from the path, giving us each an area of approximately 25m squared. We decided to sample the holly bushes by taking a measurement of a new growth at a high, medium, and low level (above the head, just below head height, and about knee height). We measured new growths as it would give us flexibility with the data as we would know the average number of leaves on a new growth, whereas measuring the number of leaves would not give us this flexibility and would also be more time consuming. We each aimed to sample 50 new growths.

Bias was an issue we would ideally have overcome by using a random number generator of some sort, but this was not available to us as we were making it up on the spot. The approached this by using a rather amateur method, which included closing our eyes and randomly holding our finger out and sampling the branch we were pointing at. This is a flawed method as it is still subject to bias and means we may not have been pointing at a plant at the right height, but it was the best we could do with the resources available to us.

After sampling at the three heights we moved around the holly bush until we had gone all the way around, measuring each about 5 times, and then moving on to the next one. We recorded the number of leaves on the new growth, and the number of leaves infected by leaf miners. We could then use this information to calculate the percentage of the holly bushes that were infected with leaf miners.

To take this further, we could have used the information to calculate the number of holly bushes infected in the entire wood. To do this we would need to know the area of the wood, but this posed the issue of variation. For example, on one side of the path where we were sampling, there were many holly bushes. On the other side, there were next to none. We would therefore need a larger sample area to calculate the average percentage of woodland covered by holly bushes, and we could then times this by the proportion of leaves that were infected to see how many new growths throughout the wood were infected. However, this would take much more time and planning than just this one field trip allowed.