Tetrapod Zoology

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Welcome to another article in the ‘over-enthusiastic swallowing’ series. As was the case with the previous article (the one on Mushu the pet bearded dragon), this one doesn’t involve the death of the animal(s) concerned. In fact – so far as we can tell – the creature(s) that did the swallowing didn’t suffer any ill effects from its/their behaviour at all. The creatures concerned are gulls: specifically, Herring gulls Larus argentatus and Lesser black-backed gulls L. fuscus [adjacent image from Camphuysen et al. (2008); read on].

Camphuysen et al. (2008) were interested in finding out what the breeding gulls of Texel, in the Netherlands, were eating, so they collected and studied the regurgitated pellets that the gulls produced. They analysed 3876 pellets (the Dutch word ‘voedselmonsters’ is used for the analysed objects: is this really synonymous with ‘pellet’?). By far the majority of pellets contained the remains of ‘expected’ prey. That is, the remains of bivalves, crustaceans and fish, and it really should be emphasised that virtually all of the pellet contents represented prey of this sort. However…

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Gulls are highly opportunistic, highly adaptable birds that don’t seem shy about ‘experimenting’ with novel or risky prey, and the study also revealed a really interesting list of anomalies. Evidence for the ingestion of berries, grapes*, fly larvae and snails was recorded. One juvenile Lesser black-backed gull had been fed rat-tailed maggots by its parents, but these evidently disagreed with it and it regurgitated them intact (Camphuysen et al. 2008). Potentially less harmless were the plastic or metallic food-wrappers eaten by gulls, including cheese and sausage wrappers, metallic tubes and bottle tops [some shown here, from Camphuysen et al. (2008)]. Bits of elastic, foil and paper were also discovered in some pellets, as were balloons. As is hopefully well known, marine birds are routinely eaten huge quantities of floating plastic these days, and are dying as a result. This is not a trivial problem: there are indications that some populations, and probably some species, are being seriously affected by this.

* Surprisingly, some gull species ingest enough plant material to act as important dispersers of seeds. In the Canary archipelago, for example, Nogales et al. (2001) concluded that Caspian/Yellow-legged gulls L. cachinnans may well be important distributors of endemic Rubia species.

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But then we get to the really weird stuff: in a study as large as this, quite a few anomalies were found. One gull had swallowed the legs of a small plastic doll [shown below; from Camphuysen et al. (2008)]. Another one ate a plastic squid-like fishing decoy (which is not so surprising, as the object looks like a real squid). 16 small army figures had been swallowed by one gull [shown here; from Camphuysen et al. (2008)], hence the reference to a ‘whole army’ in the article’s title (note, however, that the toy soldiers were little ones, not the more typical 50-mm-tall ones we’re used to). Another gull had eaten a whole medal (still with complete ribbon attached: it’s shown above), and another one had swallowed a whole mobile phone [shown at top] (Camphuysen et al. 2008). Funnily enough, the phone – a Sony Ericsson W610i – is exactly the same (now quite dated) phone that I use, and if you want confirmation look at the photo here.

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The fact that large gulls will eat incredible and ridiculous items such as these is well known among gull workers. As has been mentioned here at Tet Zoo a few times, a brand-new bar of soap, still with label attached, it also on record as having been swallowed by a gull (thanks Jerzy). I’d be interested in hearing about additional bizarre anomalies – please do mention any that you’ve heard of.

I’m indebted to C. J. Hazevoet for bringing Camphuysen et al. (2008) to my attention.

For previous articles in the ‘over-enthusiastic swallowing’ series see…

And for articles on gulls and their taxonomy, variation and phylogeny, see…

Refs – –

Camphuysen, C.J., Boekhout, S., Gronert, A., Hunt, V., van Nus, T. & Ouwehand, J. 2008. Bizarre prey items: odd food choices in herring gulls and lesser black-backed gulls at Texel. Sula 21, 49-61.

Nogales, M., Medina, F. M., Quilis, V. & González-Rodríguez, M. 2001. Ecological and biogeographical implications of Yellow-Legged Gulls (Larus cachinnans Pallas) as seed dispersers of Rubia fruticosa Ait. (Rubiaceae) in the Canary Islands. Journal of Biogeography 28, 1137-1145.

Comments

  1. #1 Who Cares
    December 19, 2009

    The dutch word monster means sample in this context.
    The complete translation of voedselmonster would be along the lines of food sample.
    So no it’s not synonymous

  2. #2 Hanneke Meijer
    December 19, 2009

    In certain parts of the Netherlands, gulls are a serious problem as they create a mess in their search for food. They are notorious for tearing apart garbage bags and scattering waste throughout the streets. I actually cycled over one once early in the morning in an attempt to catch a train while being late. The gull was too preoccupied with his search for food to notice me but he didn’t appear to be hurt one bit and he flew off. I, on the other hand, was quite shocked to have cycled over a gull. There have been experiments in Leiden to decrease the number of gulls by replacing their eggs with fake eggs, but so far no success.
    “voedselmonster” indeed refers to food sample. I had the pleasure to meet Cees Hazevoet last september on Lissabon airport while on my way to fieldwork on the Selvagens archipelago, he is a great personality.

    Cheers, Hanneke

  3. #3 Rose
    December 19, 2009

    On the theme of marine birds eating plastic trash, the link below shows what happens to some of the stuff we throw “away” :

    http://www.chrisjordan.com/current_set2.php?id=11

  4. #4 Sordes
    December 19, 2009

    Among birds ostrichs are (as you all know) notorious in swalloing incredible things. I read of a case in which an ostrich swallowed a tin can full of paint. The can opened and when the ostrich was dissected much of its upper digestive tract was covered with paint.
    There was also a case of a sealion in the zoo of Leipzig in whose digestive tract 30 kg of stones were found during the dissection. I know also of two cases (attention, no tetrapods!) in which large wels catfish (Silurus glanis) had tried to eat floating balls. They could neither swallow nor vomit the balls and died. They probably thought the balls were waterfowl or so. I know another case of a big american catfish (I think it was a flathead catfish) which also nearly died from a similar situtation, but was freed from the ball by somebody.

  5. #5 Arthur Masloski
    December 19, 2009

    Last weekend I spotted a ring-billed gull trying to swallow a house sparrow, I was driving by and when I went back for a picture it was gone. I wonder if it was already dead or if the gull caught it? I know it isn’t quite as strange as a cell phone but it was interesting to see anyway.

  6. #6 AnJaCo
    December 19, 2009

    Nice cautionary post about proper waste disposal by us humans.

    This post is also useful for noting that critters eat lots of different things. If we knew these gulls from the fossil record only would our inferences about their diet match up well with these findings? Probably not. For example, we would probably miss the plant bits. [Certainly the cell phone and doll legs]. Nothing special about gulls in this respect, though, they are quite the generalists. Analyses of diet via gut content examination for most tetrapods usually produces long lists of all kinds of things – many unexpected. Important to keep in mind when inferring the diet of extinct animals.

    My Fun Found Food item story involves a DOR striped skunk whose skull I coveted. After dissecting out the skull, and “as long as I was there”, I checked its gut contents. Yellow Jacket wasps – from the stomach all the way to the large intestine. Lots of them. Nothing else. BTW skunk odor is a whole different ballgame ‘up-close and personal’ when compared to the gentle temporary scent one usually encounters while driving. I find the latter somewhat pleasant, actually.

  7. #7 Albertonykus
    December 19, 2009

    I’ve heard of instances where gulls swallowed live rats and died from getting chewed on from the inside. This seems to have happened to herons, too.

  8. #8 Mark Lees
    December 19, 2009

    Greater Black-backed Gulls have been recorded as having caught migrating birds the size of a blackbird and swallowed them whole.

    I wonder what influence the prevalence of gulls as scavengers is having on the recovery of red kites. In the middle ages red kite was a major scavenger in much of the British Isles, even in cities and at rubbish tips, but with its extinction in most areas gulls seem to have taken over the role. Red kites are on the increase (within the last decade they have started to breed a few miles from my home again), but we dont seem to see them scavenging on rubbish tips. I can’t help thinking that the presence of large numbers of gulls may be a factor. The larger gulls (especially Greater Black-Backed) are more serious predators than many of the raptors.

  9. #9 wolfwalker
    December 19, 2009

    Mark: This past summer I and a dozen other people watched a Great Black-backed Gull catch and kill a Common Tern (length 14″, wingspan about 30″), and swallow it whole. It had to work a while to do it, mainly because of the tern’s dangling wings, but eventually it got the whole thing down. Afterward the gull flew away, and didn’t even look like it was flapping any harder than usual. One person got several decent photos of the incident. The fifth one in the slideshow is especially striking. Not recommended for the squeamish.

  10. #10 Rob
    December 19, 2009

    There’s a Great(er) Black-backed Gull in New Jersey that likes to feed on American Coots: http://www.birdcapemay.org/blog/2009_10_25_archive.html.

  11. #11 BruceK
    December 20, 2009

    #2 In certain parts of the Netherlands, gulls are a serious problem as they create a mess in their search for food. They are notorious for tearing apart garbage bags and scattering waste throughout the streets.

    Near Falmouth (on the south coast of Cornwall, in S.W. England) this a notorious problem, so much so that the boxes used to to leave out rubbish for recycling have special covers.

  12. #12 anon
    December 20, 2009

    “16 small army figures had been swallowed by one gull ”

    This one amuses me because, hey, anybody can make the mistake of eating the occasional random bottle cap or mobile phone, but in this case, we have to imagine the gull eating the first soldier and thinking to itself, “Hmm, not bad — guess I’ll just eat the rest of these…”

    Such completely nonsensical behavior seems almost human, cf. http://www.darwinawards.com/

  13. #13 Jerzy
    December 20, 2009

    “if we knew these gulls from the fossil record”

    Every paleontologist would say, on the basis of cell phone, that they ganged in flocks and hunted humans.

  14. #14 Andreas Johansson
    December 20, 2009

    Nah. A few brave mavericks would insist they were obligate scavengers, and only ate humans that’d died from other causes.

  15. #15 Dartian
    December 21, 2009

    Darren:

    16 small army figures had been swallowed by one gull

    The infantry was utterly defeated by the enemy’s air force.

    Arthur:

    Last weekend I spotted a ring-billed gull trying to swallow a house sparrow, I was driving by and when I went back for a picture it was gone. I wonder if it was already dead or if the gull caught it?

    Either alternative is possible. Gulls may catch small birds whenever they get the chance. I once happened to see how a herring gull (seemingly) casually walked by a chaffinch Fringilla coelebs that was hopping on the ground in a city park; when the gull got close enough it suddenly caught the finch and swallowed it. And I’ve heard of a mew gull Larus canus that had learned to ambush house martins Delichon urbica near their nests and catch them in flight.

  16. #16 AD
    December 21, 2009

    When I was in Brittany I noticed astonishing amounts of garbage on the beaches, even noticeable from the tops of tall cliffs. This is much worse than anything I’ve come across in the States, including beaches in the Northeast US, although I haven’t been to NYC beaches like Rockaway. Why is this? Different currents or different habits?

  17. #17 kelvin britton
    December 21, 2009

    Re: Red kites and Gulls – while looking for an Azorean Yellow-legged Gull near Didcot in October, it was interesting to see over a dozen kites around the rubbish tip, and one sitting in the middle of the loafing gull flock; no interactions between the species were noted at all.

  18. #18 Boesse
    December 21, 2009

    Several years ago my girlfriend and I were in my field area in Santa Cruz, California, and we surprisingly watched a gull eat a sea star – whole. This was an ocher star (Pisaster ochraceus) that was 3″ wide – first it got down one arm, then a second; it battled another 10 minutes to get the third leg down, and after that, it started to slide down it’s gullet. Afterward, it had a huge lump in its neck, and for a while a single arm poked out of its throat. The ordeal took about 20 minutes, and I’ve got some OK pictures of it. Weird.

  19. #19 Cale
    December 22, 2009

    Dunno if this applies to the discussion, But I grew up in a small seaside town. A real messed up town, in alot of ways.

    I remember the more sadistic and malicious boys telling me about casting whole fish on big hooks out into the water for gulls to swallow, the idea being they could then ‘fly’ the gull like a kite.

    That, or they’d tell stories of rolling alka-seltzer pills or drano in bread and making the gulls ‘explode.’ I dunno how much veracity these stories have, but it does go to show how messed up small-town bully-minded kids can be.

    As an aside, I have also seen MANY a gull swallow a starfish, and have always wondered how its possible. I assumed it’s just because everything’s ‘looser’ in a bird’s throat.

    Question: How does the starfish move from the crop to the stomach proper? Do birds generally begin digesting their food when it’s in the crop?

  20. #20 jomega
    December 22, 2009

    I once saw a gull that had attempted to eat an entire baguette. In some absurd fit of gustatory bravado, it had apparently tried to swallow the thing whole, and as a result was wandering around with a grotesqely distended neck, stuck staring straight up at the foot or so of hard bread still protruding from its maw.

    Cale’s post (#19) reminds me of the time a limo driver was parked at the seaside establishment I worked at once. A gull, acting in accordance with its nature, crapped all over the dude’s car. The driver, bent on revenge, retreived a tackle box from his trunk (Standard equipment for limo drivers? I don’t know), secured a treble hook to either end of about a 20 foot length of fishing line, baited each hook with a wad of bread and snagged a gull on each end of the line. I’ve heard of the Alka-Seltzer technique as well, but have never witnessed it in practise.

  21. #21 Cale
    December 24, 2009

    the ever-handy askabiologist.org.uk (great site, btw) assures me that the Alka-seltzer thing isn’t possible, but still, if the story is that prevalent, it makes a man wonder.

    Personally, I find the attitude towards ‘scavenger’ animals like seagulls to be kind of…. well disgusting, I guess, among laypeople.

    Seagulls, coyotes, possums, seems anything that is commonly seen as a ‘scavenger’ animal is somehow ‘less’ than other animals, and even people who aren’t normally cruel-natured will talk about these animals with an air of disdain. A friend of mine practically worships the bald eagle, and will believe any fantastic story he hears about them uncritically, and yet considers the crow and the seagull just short of worthless. An all too common bias.

    I argue for more appreciation for the scavenger animals, though in this online crowd, I have a feeling I’m preaching to the choir.

  22. #22 Ramond
    December 25, 2009

    I once heard (not seen directly, though) about seagull swallowing a metal fork. The bird than walked stiff-bodied for half an hour and than – amazingly – was seen behaving completely normal. Wether the fork dissolved in the gastric acid (which is what the observer presumed) or the gull simply regurgitated it (which I deem more probable) I am unsure.

  23. #23 Emily
    December 30, 2009

    City gulls make a habit of preying on migratory birds that collide with buildings. When I volunteered with a non-profit that collected casualties & rehabilitated stunned birds, I not only had the chance to encounter species I’d never seen in the wild, but watched gulls scarf back several stunned birds that were very much alive.

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