RFI - Coot nesting habits (1 Viewer)

[Thing]

I wonder if any of you can help. I have a pair of Coots in my patch that over the last couple of years have failed in all attempts to hatch eggs - basically due to the tidal nature of the water course that they nest in/on. Compared to other nests in the region (London) and I guess, most of their range, the nest is quite typical in size and location (if a little unconventional in the materials used) and in particular the height from the water level. The question in my mind is along the lines of ‘Do coots nest in higher nests, or build higher structures’. Moorhen (as most of you will know I’m sure) have no compunction in nesting high up on a river bank in the same area.

Where I am particularly interested in knowing more about their nesting habits, is not in literature that I possess, and I’m wondering if there is any more detail in one of the more comprehensive books (BWP?) etc, and if so is anyone able to share it with me? Indeed, does it exist!?

Thanks in advance for any info (or not!).

 

[mikfoz]

Coots nest successfully alongside any still water and running water where there is an abundant supply of submerged small animals/vegitation on which to dive/dabble and sufficient cover in which to construct a twiggy/reedy nest.

The nest is at about water level or a few inches above it. This is massively successful in lakes/ponds. However, in tidal areas this could be disastrous. A spring tide will possibly flood the nest which would baffle a wandering bird as it wiil react to what it thinks of as an occasional, what can you do, get on with life flood and just reconstruct. Should the spring tide just be high enough to "flood" every 2 weeks this would tax the intellect of a Darwinially Challenged bird and it would regroup and reconstruct ad infinitum and eventually select out (it is hoped).

I think this is probably what is happening. Nature will adjust and the Coot as a species will continue to flourish or will diverge into tidal and non-tidal races.

 

[cjay]

I have seen Coots nests in trees three metres above the water

 

[mikfoz]

I have seen Coots nests in trees three metres above the water

True... they are the smart ones where it is necessary.

The species that survives is not the strongest, but the most adaptable to change. Perhaps they moved in from an area where nesting is at water level or just above and can't adapt.

 

[Thing]

However, in tidal areas this could be disastrous. A spring tide will possibly flood the nest which would baffle a wandering bird as it wiil react to what it thinks of as an occasional, what can you do, get on with life flood and just reconstruct. Should the spring tide just be high enough to "flood" every 2 weeks this would tax the intellect of a Darwinially Challenged bird and it would regroup and reconstruct ad infinitum and eventually select out (it is hoped).

I think this is probably what is happening. Nature will adjust and the Coot as a species will continue to flourish or will diverge into tidal and non-tidal races.

This is exactly what I've been observing - they do not have the mental capability to work out (think about) what is happening. The nest fails, they make another one. The eggs float off, they lay some more. There are others further down river, below a weir, which have a few hours of exposed mud each day and still start making a nest as soon as there is something to anchor it on.

I'm not sure that it is because these particular birds are from a particlarly weak gene pool, but there is only so much territory to go around (and here I dont think that there is enough) and the first pair mentioned have a 'better' territory than those further down the river, and those that have to exist on the main body of the Thames.

I guess I'm wondering if there are examples of adaptability (apart from the tree nesting!), but beyond a record of them moving upwards another 45cm, there doesnt seem to be much going on.

Thanks for the comments though!

 

[Alan Tilmouth]

Some of the early studies in BB suggest a 28-32% failure rate due to flooding even on nesting sites that are non tidal. The same study mentions the heights of one or two observed 'brooding platforms' as being between 2.5-3.5 ft above water but makes no mention of nest height.
BWP suggest nest height ranges from 8-28cm and can be built up against rising water level to 45cm.

 

[Thing]

Some of the early studies in BB suggest a 28-32% failure rate due to flooding even on nesting sites that are non tidal. The same study mentions the heights of one or two observed 'brooding platforms' as being between 2.5-3.5 ft above water but makes no mention of nest height.
BWP suggest nest height ranges from 8-28cm and can be built up against rising water level to 45cm.

Thanks Alan. Facts, I like them.

The platform fact especially, might give me something to work with...