Lack of waterbird diversity on lodge lake

Mute Swan and cygnets - Lodge Lake, Milton Keynes
Mute Swan and cygnets - Lodge Lake, Milton Keynes
I keep wondering why there are only really Mallards, Canada Geese and Mute Swan on Lodge Lake, Great Holm (or rather why the few other species of waterfowl that do stop by don’t stay for more than a day or two at most), regular readers of my blog will know that tufted ducks are a scarce bird popping through once or twice a month (if that), Gadwall are an extreme rarity (1 this year so far and none I saw last year) any other ducks (Smew, Garganey and Pochard are the only others recorded there) are mega rare birds. Greylag geese fly over (very rarely) or stop for a few moments (even rarer) and that is it for visiting geese (OK so I'm not expecting other swan species really, but they are waterfowl and present). So what causes this?

What Water Birds are there


Male Tufted Duck (A scarce bird on the lake)
Male Tufted Duck (A scarce bird on the lake)
Lodge Lake Milton Keynes
The number of waterbirds on the lake is not huge (It isn’t a large lake around 8 hectares) so I wouldn't expect many really but more than there are, there are good numbers of Mallard (never counted totals sorry, must do that next time I'm out, but the numbers fluctuate), Canada Geese (approx. 6 -8 pairs, again I need to count), 1 pair of swans, 3 pairs of Great Crested Grebes (I think), 1 pair of Little Grebe (at least), plenty of Coots and lots of moorhens, but that is it.


Lake make up


Now I know the lake isn’t large, like I said around 8 hectares, and varies in depth from about 2 feet (in some margins) up to 18 feet in others. There are good fish numbers (and species counts as it gets quite a few fishermen), and there are different habitats at the edges from grass areas to wooded overhangs and reedbeds. 

What I don’t know is about the pond life in the water (I have tried pond dipping with my daughter and found a few small insects but the edges are very rocky where you can get near). I do know there are pretty good damselfly numbers (Azure, Common Blue, Blue-tailed and Large-red damselfly, as well as Common Darter, and some of the larger dragonflies), Midges and other flying insects occur in good numbers as well (evident in summer). With Mallards and Canada geese in good numbers I’d assume there must be something to eat (carp numbers and sizes would indicate a good supply of food as well).

Flow


Lodge Lake water flow map
Lodge Lake water flow map
The arrows show direction.
The one thing I do know is that there is a flow to the water (through the main part of the lake at least), it
comes in from upstream in Loughton and heads off down through to Loughton Valley Park and on to Bradwell Abbey (see Flow map), I know at times of heavy rainfall this flow can be quite powerful but most of the time it is very minor.

Other factors


What other possible factors are there, well there is a large amount of people traffic, fishing (although not in close season), joggers and dog walkers, and the lake is small so this disturbance could offer an explanation, but there are areas that are very under exposed to disturbance (the area on the map with no water flow through it for example), and shy birds such as little grebe manage to eke out a living.

Could a lack of passage through the area be an issue? Well that is possible, although as Gadwall, Garganey, Tufted Duck, Goosander, smew and Greylag geese and who knows what else have all passed through at some point so I would think no. The area also has large roads and the railway nearby that may be used as navigation tools. However the other lakes on this side of the city (Furzton and The Teardrop lakes) are also not very well used by wildfowl so maybe this is a reason?

The pair of Mute Swan may also play a factor as they can be VERY aggressive, I've seen them chasing off plenty of the resident Canada Geese, and they are reported to have killed one of their two offspring last year before chasing off the remaining one earlier this year. I could see this as a reason geese may not stop (or the Canada geese chasing them off) but they don't really show aggression towards ducks.

Conclusion


I can’t really see a single stand out reason for the low waterfowl numbers, and without testing of the water  itself for contamination, visibility levels, over stocking of fish or actual evidence of food I guess I’ll never really know. If anyone has any thoughts or possible information I’d love to hear about it, please leave me a message with your thoughts.



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2 comments:

  1. Your idea about the Mute Swam seems interesting to me. I live by a large lake in the Northeastern US that has been colonized by a pair of Mute Swans. One is often seen around the lake come spring and summer, chasing and harassing all the other waterfowl. Only Wood ducks escape their aggression, by Mute Swans can't fit into the same edges and overhangs that the ducks enjoy.

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    Replies
    1. It might work as an explanation around spring (as you say this is when they are more aggressive) but autumn and winter months they are usually very placid, but still no ducks!

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