Dereks full list was :-

Great Crested Grebe 6,Cormorant 60,Little Egret 20, Grey Heron 15, Spoonbill 2, Mute Swan 8, Canada Goose 3, Shelduck 180+, Wigeon 280+, Teal 10, Mallard 50, Buzzard 2, Pheasant 5, Oystercatcher 80+, Avocet 41, Lapwing 60, Dunlin 6, Black-tailed Godwit 10, Bar-tailed Godwit 2, Redshank 8, Greenshank 5, Common Sandpiper 2, Black-headed Gull 100+, Herring Gull 50+, Great Black-backed Gull 10, Feral Pigeon 10, Woodpigeon 10, Kingfisher 1, Pied Wagtail 1, Blackbird 2, Redwing 10, Magpie 2, Carrion Crow 100+, Starling 50.

‘Three billed Spoonbill!!’

Drakes Island is the only nesting site of Little Egret in the Tamar Valley. It also supports a winter and high tide roost of almost all the egrets that use the Tamar Valley ie 70-80 birds. Little Egret is one of only two species listed (the other being Avocet) in the Tamar Valley Special Protection Area designation. This  falls within the European Birds Directive 1979 (79/409/EEC) which is the oldest nature conservation legislation in Europe and establishes a comprehensive scheme of protection for all wild birds. Spoonbills also use the roost on occasions and there are several other species of breeding seabirds.

The directive bans activities that directly threaten birds, such as the deliberate killing or capture of birds, the destruction of their nests and taking of their eggs, and associated activities such as trading in live or dead birds.

Whilst the developers have submitted mitigation measures, conservation bodies considered these were insufficient to prevent disturbance to the roost and nesting colony. The latest planning application is listed here :

http://www.plymouth.gov.uk/planningdoc-2?appno%3D14%2F00001%2FFUL

They have added further information (listed under ‘Covering email’ in the Application section) but the bird report is weak to say the least. In my opinion, Plymouth City council must therefore refuse the application or risk contravening the Birds Directive. We have until 6th May 2014 to comment on the application.

If you enjoy watching Little Egrets in the Tamar Valley please support the conservation organisations and object to this application. This link will take you to the comments page: http://www.plymouth.gov.uk/planningapplicationsv4/comment.asp?AltRef=14/00001/FUL

Well it had to happen one day – the weather was somewhat grey and damp to say the least. Still 50 or so people braved the elements and while waiting at Saltash several of the party watched a Peregrine on the bridge. We began our usual  route up the River Tamar. As we were on neap tides the birds were rather distant in the lower reaches of the river and the large mussel banks normally exposed at low tide remained covered. However this was compensated by the fact we were able get further upstream than normal and we had great views of Avocets, some feeding on the mudbanks and some in the water, upwards of 150 in total. Other highlights were good numbers of Shelduck and a large flock of Lapwing. On the River Lynher, three Spoonbill were on the north shore near to where we saw them on the last trip. However on this occasion they chose not to fly down to roost on Rat island preferring to fly onto the saltmarsh. As they were 2 adults and a juvenile it is probable that they were the same birds as those seen in November. The dull weather limited the opportunities for photography so no images on this occasion. Thanks to all involved – lets hope for better weather next January.

Notable counts recorded on 15^th December 2013 by Derek Julian

Bruce Taggart   (reproduced from CBWPS ‘Palores’ Spring 2013)

The Eurasian Spoonbill is a rare passage migrant and winter visitor to Cornwall, but the estuaries of the River Tamar complex including the River Lynher are regular haunts, with up to seven individuals wintering in recent years. Birds usually arrive in November and remain until February / March. Sightings of ringed birds indicate that most, if not all originate from the breeding population in the Netherlands which in 2004 numbered around 1500 breeding pairs. Since 2006 I have been running bird watching cruises on the rivers and we have observed Spoonbills on over 30 occasions, often foraging on the flooding tide. They favour the lower Tamar, below Kingsmill Lake and the confluence with the River Tavy and on the River Lynher, usually east of Wacker Quay. At high tide they roost either on Beggar’s (Rat) Island or on areas of saltmarsh further up the Lynher or in Kingsmill Lake.

Spoonbills are seen foraging in shallow water, usually between 100mm and 450mm. They walk forward with the bill tip submerged and held slightly open with a side to side sweeping action. Once prey is detected, the bill snaps shut and the head is jerked back throwing the item into the throat. (This is because spoonbills have relatively short tongues in relation to their bill length and are unable to manipulate prey prior to swallowing). BWP lists Spoonbill prey items as mainly insects and their larvae, especially water beetles, dragonflies, caddis flies, small fish, amphibians, aquatic snails, and some vegetation. However, most of these may be associated with fresh water, rather than the brackish or saline conditions of an estuary.

So what are the Spoonbills eating and how do they detect prey items? Some authorities’ state that it is purely tactile, the wider part of the bill acting as a sieve to extract small prey from the sediments, similar to Shoveler. This is unlikely to be the case as the mandibles lack the required lamellae. Our observations indicate that prey is caught in the water above the sediment and is more likely to consist of fish, shrimps and marine worms.

Weihs & Katzir(1994) hypothesised that the shape of the bill acts as a hydrofoil over the substrate, lifting prey into the water that would be captured during the following sweep. They created this mainly on observation of captive spoonbills. They assumed the fact that the inner profile of the upper mandible was concave; shedding a vortex over the mud and the bill was held close to the bottom substrate irrespective of water depth. Molluscs in particular would be caught in this way.

Conversely I tend to agree with Swennen and Yu (2008) who rejected this idea centred upon three parameters. Firstly their analysis of prey size and type; fish and shrimps would immediately swim away if disturbed. Secondly, bill shape; the upper mandible is in fact convex not concave and thirdly the height the bill was held above the substrate, often higher than required to create sufficient disturbance to the substrate.

We have also observed Spoonbills actively chasing prey in the water. Considering the turbid nature of estuaries they must rely on senses other than sight to find prey. There have several recent papers describing some birds (notably waders and kiwi) ability to detect prey by picking up vibrations, termed ‘remote touch’. These birds possess a honeycomb of sensory pits within the bone of the bill tip packed with pressure sensitive mechanoreceptive nerve endings. Cunningham et al (2010) identified similar structures in ibises and spoonbills with the latter having up to 20,000 of these pits compared to several hundred in other species. This suggests Spoonbills rely heavily on remote touch to detect prey.

It has also been suggested that birds use electroreception to obtain food. This is the ability to detect naturally occurring electric fields possibly to the microvolt or even nanovolt (one thousand millionth) capacity. Duck-billed Platypus have a sophisticated electroreception system whereby they can detect and identify prey with the help of specialised receptors in the bill. It is probable that future research will find similar systems in birds. The fact that Spoonbills are hunting in water supports the electroreception theory. I suspect that when a bird is chasing prey through turbid water it knows exactly the identity of what it’s following and how it is likely to behave – whether it will swim away or hide in the mud. That would greatly increase its chances of capture.

One final point. Having detected the prey and it has touched the open mandibles the reaction time must be quick. I couldn’t find any data for Spoonbills but experiments with American Wood Ibis (in the same family) has shown that the bill snaps shut in around 25 milliseconds  ie 1/40^th second.

There is a tendency to compare birds’ senses to those of humans. However in some areas birds are far more advanced. It is well known they are able to sense the earth’s magnetic field and see ultraviolet light and as these notes illustrate new senses are being discovered. The basis for many of these new discoveries is observation combined with science. So next time you see a bird, don’t just look at it, but watch and record its behaviour.

Acknowledgements

Thanks to all participants on boat trips who have questioned and stimulated discussion about feeding Spoonbills and especially to Charlie Bird for supplying the excellent accompanying images and to Chris for patiently enduring my birding obsession.

References

Cramp, S. and Simmons, K. E. L. 1977. Handbook of the birds of Europe, the Middle East, and North Africa: the birds of the western Palearctic, 1. Oxford University Press, Oxford

Cunningham, S.J., Alley, M.R., Castro, I., Potter, M.A., Cunningham, M., Pyne, M.J. 2010. Bill morphology of ibises suggests a remote-tactile sensory system for prey detection. The Auk 127(2):308-316.

Swennen, C. and Yu, Y. T. 2005. Food and feeding behaviour of the black-faced spoonbill. Waterbirds 28: 19–27.

Swennen, C. and Yu, Y.-t. 2008. Bill sweeping in spoonbills Platalea: no evidence for an effective suction force at the tip. Journal of Avian Biology, 39: 3–6. doi: 10.1111/j.0908-8857.2008.04299.x

Weihs, D. and Katzir, G. 1994. Bill sweeping in the spoonbill, Platalea leucorodia: evidence for a hydrodynamic function. Anim. Behav. 47: 649–654.

We turned and sailed back down river before passing under the Tamar Bridges and then heading up the River Lynher where a pair of Red-breasted Merganser were quite close. Then ahead, two Spoonbills were spotted, feeding in the shallows but unfortunately soon flew off as we drew alongside. The birds were both juveniles identified by their black wing tips. All the birds on the Lynher were unusually flighty today with large groups of Wigeon, Teal and Black-tailed Godwit all taking to the wing as we passed by the mud opposite Wacker Quay. Here a group of Avocet were very close and gave us marvelous views of this iconic bird. Around the bend and on towards St Germans, another Greenshank, together side by side with a Redshank, enabled a good comparison between these two species. By now the river was very shallow and we turned back for Saltash but were treated to excellent views of 3 Spoonbill off Rat Island winding up another enjoyable day on the river. After dropping most passengers off at Saltash we headed back to Cremyll, adding a smart adult Mediterranean Gull to the list. The traditional post trip carvery at the Edgecumbe Arms was especially good today!

Many thanks as always to Derek, Nigel, Pete and Tony for their help in spotting the birds and general contributions. Tony’s photographs to follow.

Dereks counts were as follows

17th November 2013 11.00am

15th December 2013 10.30am

29th January 2014 10.00am

15th February 2014 12.00 mid-day

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