Sunday, 20 August 2017

A Moorhens Tale

Autumn is starting to show its hand, the Robin's song has changed and there is a different quality to the air in the morning. Bird-wise we have entered a lull between the seasons. The Saxon Mill was remarkably quiet, a lone Chiffchaff sang its song and the Whitethroats have all left for Africa and in the skies, the Swallows were starting to gather in swooping clouds.

Adult Moorhen

Sat beside the river waiting for the Kingfisher to show I found myself watching a juvenile Moorhen. At this time of the year, they have lost the cute a cuddly black fluff and are now something of a drab black and brown bird. It pottered along the edge of the water in a skittering careful manner, it was joined by a second and I heard a third unseen to my right. I began to think about how successful this bird actually was on my patch, more so perhaps than the other ubiquitous waterbird, the Mallard.

Mallard are common on the river; more so in the winter than the summer when they pair up to mate. However, ducklings last only a very short time on the river. Each year I see one maybe two broods and they rapidly diminish. 1st Year juvenile survival is 0.518 and appears much higher on my patch. The river is a dangerous place for small nestlings, struggling to survive to fledging. Under the water the river is teeming with Pike whilst above ground there are two pairs of foxes in the area, Mink frequent the area and Otter have been seen as well. They are not safe from their own kind either, Kestrels and Sparrowhawks are common on the site, but these are unlikely to present to much of a threat instead their avian foe is the Grey Heron. All these predators would make short work of either a duck or moorhen chick but it seems that Moorhens at least have a greater survival rate on the river.

Mallard with large brood at the mill, most of these ducklings won't make it another week


Mallard clutches tend to be larger than Moorhen and their food sources and predators are the same and yet the Moorhen seems to do better. This could be due to the ability of the Moorhen to have two broods compared to the Mallards one. This would certainly boost numbers and aid survival but whilst watching the juveniles I began to think that perhaps behaviour and morphology have a part to play.

Moorhens are more cryptic in behaviour than Mallard, yes females have excellent camouflage but once hatched the young are more vulnerable for longer. Newly hatched chicks of both species are highly vulnerable in the first couple of weeks but as they grow the ducklings remain more vulnerable. The Moorhen juveniles become more mobile, they are more wary on the water and faster on the land. They skulk in the shadows instead of being visible on the water. At the Saxon Mill where there are abundant predators it is the Moorhen that has greater flexibility in both hiding and evading predators and so their breeding success is greater.

Moorhen with Chick - less than a week old


If you compare the breeding on the river to that on the canal survival between the Moorhen and Mallard is more even with many more ducklings evident and predators are fewer.

It’s interesting how even the commonest of birds can have such interesting lives.