SPURTING
BEHAVIOUR' in waders
Background
Black-tailed
Godwits regularly feed in Emsworth Harbour in the
winter period - Oct-Mar. I have watched them for many
years, mainly logging the colour-ringed birds. From
photos (usually digiscoped), I have many examples in
which the Godwits appear to be actively spurting water
from their bills when feeding.
Roughly, the behaviour is as follows: the bird dips
its bill into the water for a couple of seconds, or
so, to obtain food. It then withdraws its bill for a
moment and pushes foward slightly, usually (though not
always) with the bill lowered and 'spurts' out a
stream of water, as if ridding itself of surplus taken
liquid taken in during the underwater feeding. The
bill is then reinserted into the water and the
sequence of behaviour is repeated. All this happens
very quickly, though video clips I have taken through
my scope show the behaviour reasonably well.
The behaviour is not confined to Black-tailed Godwits.
I also have photos shown below of Greenshank,
Spotted Redshank and Common Redshank all
apparently 'spurting'. See below.
Mystery
behaviour
I consulted
various Godwit experts, none of whom had ever seen or
heard of it, or knew why it should happen. Pete Potts
suggested I should send the photos to Dr Humphrey
Sitters, Editor of the Wader Study Group Bulletin, who
sent them on to international wader authorities who
likewise did not know anything about it either.
Anne de Potier was in Portugal with the Godwit ringing
and recording team in February 2012 and asked the
assembled crowd whether anybody knew anything about
spurting, and Matt Thomas, a wildlife warden from the
north west and keen photographer, piped up. Yes! He
had pictures taken in August 2011. Anne said none of
the assembled, more experienced, people had seen it or
heard of it.
Here is the link to Matt's 'blog' - look for 4 August
and 24 August 2011. http://deebirder.blogspot.com/2011_08_01_archive.html
It is interesting, that on 24 August Matt says he can
see worm entrails coming out with the spurting water.
Publication
I was
surprised that various wader experts I consulted (a)
had not seen what seems to me to be fairly common
behaviour among Black-tailed Godwits and other waders,
or (b) know why it should happen. So, at the request
of Humphrey Sitters, the editor of the Wader Study
Group Bulletin, I wrote a short article on 'spurting'
behaviour with photos. After a very long delay, the
article was finally accepted for publication - my very
first ornithological publication!
See
. . .
'Spurting
behaviour in wading
birds'
.
. Published in the Wader Study Group Bulletin Vol 120
(3) 2013 pp 208-209
SPURTING
DIARY in
reverse chronological order
WEDNESDAY
AUGUST 22 - 2018
Godwits 'spurting' and 'bubbling'!
On Monday (Aug
20) Chris Cockburn was taking random photos of
Black-tailed Godwits feeding in the HCC Marsh Field
from the Hayling Billy Trail north. He says it had to
be 'random' because of his AMD vision problem.
The Godwits were frantically feeding on what Chris
thinks were Hydrobia species whilst
standing in water approximately up to their leg
length, thereby necessitating deep probing with their
bills. Interestingly, Chris captured one Black-tailed
Godwit spurting water from its bill.
'Spurting' behaviour
in Black-tailed Godwits and other waders was a topic
that interested me several years ago. In addition to
Black-tailed Godwits I also have observed Greenshank,
Spotted Redshank, Common Redshank and even Spoonbill
'spurting'.
I consulted various Godwit experts, none of whom had
ever seen or heard of it, or knew why it should
happen. Pete Potts suggested I should send the photos
to Dr Humphrey Sitters, Editor of the Wader Study
Group Bulletin, who sent them on to international
wader authorities who likewise did not know anything
about it either. Eventually, I was asked to write a
paper which was published in this learned
ornithological publication.
You can see my sightings, photos and discussion of its
function on a special page on this web site at . . .
Spurting
behaviour
Today Chris got
another photo of a Black-tailed Godwit this time
apparently squirting air or water below the water
level creating bubbles. Chris thinks this might be a
behaviour to move soft mud and expose
Hydrobia sp (or other small prey items).
I don't recall having seen this bubbling behaviour.
Does anyone else have observations and photos of this
unusual behaviour?
FRIDAY
October 24 - 2014 - Nore
Barn
Tony Wootton
paid a visit to Nore Barn and captured the Spotted
Redshank and a juvenile Black-tailed Godwit feeding
together in the stream.
MONDAY
JANUARY 13 - 2014 - Nore
Barn
11:15 - 12:15
- The tide was still well in when I got to Nore Barn
(high water was at 09:30). The stream was full of
water, but the ever faithful Spotted Redshank
was present, feeding on the foreshore. This was my
first visit to Nore Barn since Christmas, so I was
pleased to see it, though most of its 'friends' had
gone. I got one shot of it apparently 'spurting' water
from its bill.
FRIDAY
DECEMBER 20 - 2013 - Nore Barn
86
Black-tailed Godwits at Nore Barn. Lots of 'spurting'
was going on while the godwits were feeding in
water.
WEDNEDAY
NOVEMBER 12 - 2013 - Nutbourne Bay
About 200
Dunlin were busily feeding on the edge of the falling
tide along with a few Black-tailed Godwits, which
looked as though they were 'spurting' so I took some
photos. Sure enough I did capture one bird in the act
as shown here.
FRIDAY NOVEMBER 8 - 2013 - NORE BARN
Black-tailed
Godwits - 88 flew onto the mudflats in Nore Barn
Creek where they fed on the near shore before flying
over to the far shore by the saltmarshes. I captured a
couple of examples of the Godwits apparently
'spurting' water from their bills.
WEDNESDAY
OCTOBER 9 - 2013
One of my
photos today at Nore Barn Emsworth showed a
Greenshank 'spurting' while feeding in the
stream. I have just one other photo showing a
Greenshank spurting taken on 08-Feb-12 at Nore
Barn.
MONDAY
APRIL 29 - 2013
Mike Wells
took this photo of a group of Black-tailed
Godwits, some in their orange breeding plumage
feeding in the 'Texaco Bay' area on North Hayling Of
special interest to me is that one of the Godwits is
spurting water from its bill.
FRIDAY MARCH 22 - 2013
The Spotted
Redshank was feeding very actively in quite deep water
in the stream, sometimes immersing almost its whole
body under the water. Here is a photo of the bird
apparently 'spurting' water from its bill.
THURSDAY
FEBRUARY 28 - 2013
When I
returned to Nore Barn at about 11:45 the stream was
full of water and Spotted Redshank was feeding at the
top of the stream near the small bridge. As it was
nice and close I took lots of photos. Three of the
photos showed the bird apparently spurting out water
through its bill. Here is one of them
Friday
February 22 - 2013
Peter
Milinets-Raby observed a Greenshank at Warblington
'spurting' as it grabbed a big wiggly worm and spurted
the water out. Peter added, "I observed the Greenshank
at very close quarters and to me all the bird did was
force out the water and sand granules that it had
taken down with the wiggly flat worm into it's gullet.
The Spotted Redshank does the same after feeding for
two three minutes, taking in food, sand particles and
excess water into the gizzard/gullet and just like
regurgitating food for youngsters it spurts out the
water and particles it does not want. Just like an Owl
or a Shrike with its pellets".
Wednesday
December 5 - 2012
On looking
through my photos of the Black-tailed Godwits feeding
in shallow water at Nore Barn, I found two that showed
birds spurting water from their bills. One of the
godwits appeared to be spurting objects with the
stream of water.
Here
is a Black-tailed Godwit simply spurting water
Here
is another Black-tailed Godwit spurting objects with
the water
Spoonbill
'spurting' (13 December 2002)
Here is an
interesting one that I discovered when going through
my old photos. It shows the Spoonbill that turned up
in Emsworth Harbour in Nov-Dec 2002 apparently
spurting water from its bill. This so-called
'spurting' behaviour has been seen numerous times in
recent years in Black-tailed Godwits, Greenshank,
Spotted Redshank, and other wading birds. It remains a
mystery baffling even the ornithological
boffins.
Spoonbill
'spurting' while feeding in Emsworth Harbour in
December 2002
SATURDAY
NOVEMBER 3 - 2012
The Spotted
Redshank was constantly digging deep in the Nore Barn
stream
and in one of my
photos I discovered that it appeared to be spurting
out water from its bill at the end of a feeding
episode.
I have previously seen
this behaviour mostly in Black-tailed Godwits, but it
appears to be also not uncommon in Spotted Redshank
and in Common Redshank. The experts are currently
puzzling over this behaviour which, very surprisingly,
has not been previously recorded.
THURSDAY
OCTOBER 25 - 2012
The tide was
still well in when I arrived at Nore Barn. I watched
the stream gradually empty over the next hour by which
time the Little Egret, Greenshank and Spotted Redshank
arrived in that order at about 15 minutes intervals.
One of my Greenshank photos shows it apparently
spurting out water from its bill.
16
March 2012
Malcolm
Phillips was at Nore Barn today and got a photo of a
Common Redshank apparently 'spurting' water from its
bill. This is the first image I have on record of a
Redshank 'spurting' to add to those of Black-tailed
Godwit, Spotted Redshank and Greenshank. It looks as
if this is a general piece of behaviour in wading
birds, at least those with fairly long bills.
8
February 2012
Greenshank
'spurting' in the Nore Barn stream.
The Spotted Redshank
also seems to be spurting in this photo
25
January 2012
Black-tailed
Godwit 'spurting'
16
January 2012
I positioned
myself in a fairly sheltered place on the path south
of the woods in front of the channel where the
Godwits gathered as the tide came in. By 14:30,
there were 86 in channel, mostly feeding in shallow
water. I watched them feeding through the scope and
could clearly see water being forcibly spurted from
their bills during the feeding process, as if they
were ejecting water taken in during the search for
food. I took a good number of photos and videos of the
Godwits feeding. Here is one for example showing a
Godwit apparently 'spurting' water.
13
January 2012
As the Godwits
were feeding in water, I took the opportunity to take
some photos through the scope to see if there were any
cases of water spurting. I could not see the spurting
at the time, but there were several clear examples in
the photos of what appeared to be water
spurting.
I also took a
digiscoped video which shows the behaviour of the
Godwits feeding. From what I could see the birds dip
the bill into the water for a couple of seconds, or
so, to obtain food, then withdraw the bill for a
moment and push foward slightly with the bill lowered
making what looks like a deliberate effort to eject
something from the bill. Although the video is not
good enough to show it, I think this is when the
ejection of water occurs. The bill is then reinserted
into the water and the sequence of behaviour is
repeated.
24
November 2011
I was
interested to watch the Godwits feeding in the stream
and saw one bird, at least, distinctly spurting
water from its bill. It appeared to be taking food
in its bill and then spurting out surplus water.
Maybe, this behaviour is related to feeding in a fresh
water stream. I think Sid Davies also took his Godwit
spurting water in the fresh water canal on West
Thorney.
This
is not such a clear photo of the spurting as I got on
October 25, but see the bird on the right
17
November 2011
Experts
puzzled over spurting behaviour
Humphrey Sitters
Editor of the Wader Study Group Bulletin sent photos
of the Black-tailed Godwits spurting water from their
bills (taken by myself and Sid Davies) to Sora
Estrella, of the School of Animal Biology University
of Western Australia. Sora has researched waders' use
of 'surface tension transport' to transport food along
their bills. She did not think the spurts of water in
the photos related to the surface tension
transport.
Sora Estrella writes: "I'm not sure Black-tailed
Godwits have been using surface tension transport in
the pictures, or even if they can use the mechanism
due to the morphology of their bills. When I have
observed shorebirds using STT they have produced only
few drops of water, because the water they expel is
the drop of water that surrounds the prey, which is a
small volume. And sometimes, when they snapped the
bills, the water was propelled to all directions."
Humphrey asks of me, "I assume that the photos really
do show water being spurted out of the bill and not
the bird withdrawing its bill from the water with
water flowing off the outside and inside of the bill?"
Looking closely at my photo and that of Sid Davies
there is no question that the water is coming from the
bill itself and not flowing down the outside.
Here
is my original photo showing two Godwits spurting
water
Here
is Sid Davies's photo of another Godwit spurting
water
Two other observations
can be made from the photos which I copy here for
convenience.
(a) Firstly, a good quantity of water is being
expelled by the Godwits, which, according to Sora
Estrella, is far more than they would take in while
feeding (or than she herself has observed). So, it
seems they are not simply expelling water taken in
with the prey they are feeding on, which was my first
thought.
(b) Secondly, the water is being forcibly
ejected and is not simply dribbling out of the
birds bills.
Ralph
Hollins proposed a solution which went as follows:
"In most cases
when probing the mud locates a substantial food item,
the bird will pull it out of the mud and ingest it by
using its own bill and throat muscles, and any excess
water that comes up with the food will drain out of
the bird's bill without any danger of losing the food
in the process.
If, however, the bird is very hungry but only brings
up what seems to be a beakful of water it may try to
ensure that it gets any food content out of that
beakful of water by first forcing the water out though
a minimal gap between the mandibles which allows the
water to go but retains tiny food items in the bill
(as with a Shoveler duck sieving its food out of the
water)."
Another thought offered by Ralph is that the birds
were forcibly washing out their bills to get rid of a
nasty taste. That might explain why two are doing it
together where the great majority are never seen to do
it; they could both have been probing the same small
nasty tasting patch of mud.
Black-tailed
Godwits feeding behaviour
I asked Pete
Potts a few questions:
1. How do the Godwits manage to open the shells under
the mud?
A: They don't open the shells. They eat the whole
shell and crush them in their gizzards.
2. Presumably the
molluscs are eaten by other waders too?
A: Yes, probably but different waders eat different
species and different age classes of bivalves and
there is still much to learn.
3. There is also a
pattern of Godwit feeding in Emsworth Harbour. What I
have noticed over the years, is that in July-Sept the
Godwits concentrate in the eastern harbour and then
move across to the western harbour from Oct onwards.
Again, due to food supply I assume?
A: Emsworth Harbour local changes are very
interesting; probably just depleting one food supply,
then moving on to another rich picking. Is the roost
site the same when feeding at each site?
Ralph's
explanation of spurting- 3 November 2011
Ralph Hollins
provides a detailed explanation of why Black-tailed
Godwits might be seen spurting water from their bills.
See the discussion and photo on Oct 25.
Ralph points out that the Slybird Blog link gives a
good and clear explanation of how minute food items
can be ingested with minimum effort by surface tension
transport. He thinks the vigourous expelling of water
shown in my photo may be a preliminary stage before
use of this mechanism.
Link . . . http://slybird.blogspot.com/2007/12/oct-2007-auk-unique-foraging-mechanism.html
Ralph explains: "In
most cases when probing the mud locates a substantial
food item, the bird will pull it out of the mud and
ingest it by using its own bill and throat muscles,
and any excess water that comes up with the food will
drain out of the bird's bill without any danger of
losing the food in the process.
If, however, the bird is very hungry but only brings
up what seems to be a beakful of water it may try to
ensure that it gets any food content out of that
beakful of water by first forcing the water out though
a minimal gap between the mandibles which allows the
water to go but retains tiny food items in the bill
(as with a Shoveler duck sieving its food out of the
water).
When almost all the water has gone, the food plus the
water left in the bill may be too small a mass for the
bill muscles to get a grip on in order to move the
food from the bill tip to the throat, and then this
use of surface tension to transport the food up the
length of the bill from the tip (where it was retained
in the filtering out process) by gradually opening the
bill, is a clever scheme to move the food uphill to
the throat (no problem in then getting the food down
the throat).
Pure conjecture but that's my best guess - your water
squirting would thus be a necessary stage before the
use of surface tension transport."
As suggested by Pete Potts I have sent a note to the
editor of the International Wader Study Group Bulletin
about this puzzling behaviour.
25
October 2011
It was not
until I examined my photos, that I noticed a couple of
the Black-tailed Godwits were apparently spurting
water from their bills. I have not seen this behaviour
before, though it might be explained as a way of
ejecting unwanted water taken in with food.
Pete Potts said he had
never heard of Godwits spurting water from their
bills. He thought it might be a world first (!!) and
worth a note for International Wader Study Group
Bulletin. Anne de Potier discovered a possible answer
to the puzzle of what they were doing
It could be due to
something called 'prey transport by surface tension of
water'. Don't ask me what it means but Anne de Potier
provided a good link to an article on it which shows a
Hudsonian Godwit seemingly doing exactly the same
thing as ours.
http://www.pbase.com/mbb/prey_transport_by_surface_tension_of_water_
Googling Surface
Tension Transport adds more details, especially
http://slybird.blogspot.com/2007/12/oct-2007-auk-unique-foraging-mechanism.html