Back in 2009 (at TetZoo ver 2, the ScienceBlogs version) I ran a series of articles on ‘over-enthusiastic swallowing’: on cases where carnivorous animals have died from choking. You see, carnivorous animals of many sorts often die from choking, and field biologists have done a good job of recording many such instances in the literature. In the interests of having this material available once more, rather than corrupted and only findable via the wayback machine, I’ve here gathered those articles together, and here they are again…
Roadrunner tries to eat horned lizard. Splits neck open. Dies.
This image shows an unlucky young Roadrunner Geococcyx californicus found dead in Brisco County, Texas, in 1998. The bird had tried swallowing a Texas horned lizard Phrynosoma cornutum, and things clearly went horribly wrong. The photo used here is from Holte & Houck (2000).
Snake 195 mm long eats centipede 140 mm long. Centipede too big. Snake dies.
Here’s another case, reported in the literature by Clark (1967). A Horned or Sand viper specimen belonging to the subspecies Vipera ammodytes meridionalis (sometimes called the Eastern sand viper) was caught on the Greek island of Euboia. It looked fat at the time of collecting, and died an hour later.
Dissection revealed what you see in the photo: this small snake had eaten, whole, a centipede 140 mm long. Wow, ambitious. While the possibility exists that handling and subsequent bagging somehow damaged the snake or hastened its demise (Clark 1967), the most likely explanation for its death is that its meal was too large.
Perentie tries to swallow echidna. Echidna too spiky, Perentie gets horribly injured. Dies.
Here’s an unfortunate Perentie Varanus giganteus that died after trying to swallow a Short-beaked echidna Tachyglossus aculeatus…
The photo is from Kirschner et al. (1996), and the accompanying text is…
Auch freilebende Warane können sich einmal verschätzen. Dieser Riesenwaran wurde Opfer seiner Gier. Beim Versuch, einen Stacheligel zu fressen, fügte er sich tödliche Verletzungen zu.
… which basically says that the lizard was a victim of its own greed, and died after getting impaled on the echidna’s spikes (though the text seems to use the German word for hedgehog… which word is used in German for echidna?). So far as I can tell, it isn’t known whether the perentie tried to eat the echidna when it was alive, or found it dead. The echidna’s spikes obviously pierced the lizard’s throat, and from then on the carcass couldn’t be successfully ejected from the mouth, death (by starvation?) being the result. I actually got to see this specimen myself on a visit to the Queensland Museum in 2019 (where it’s on display), and here are my own photos…
Caption: perentie and short-beaked echidna, Queensland Museum. Image: Darren Naish.
Caption: perentie and short-beaked echidna, Queensland Museum. Image: Darren Naish.
This isn’t the only case where spikes on the prey have caused the death of the predator: Klauber (1982) noted that the spikes of horned lizards (Phrynosoma) sometimes kill snakes that try to swallow them, and Ramírez-Bautista & Uribe (1992) reported a case where a Lyre snake Trimorphodon biscutatus died after the tail spikes of a Spiny-tailed iguana Ctenosaura pectinata pierced its stomach and gut. And, yes, there are cases involving catfish spines, antelope horns and so on.
Heron tries to swallow giant lamprey. Chokes. Dies. Second heron tries same trick. Also chokes. Also dies.
It’s well known that herons are gluttonous birds that will catch and eat (or try to eat) pretty much any animal within the right size range. Everyone knows that herons eat fish, but they also eat frogs, snakes, small mammals (including rodents and rabbits), and birds including doves, grebes and ducklings.
Over-enthusiastic attempts to swallow large prey items have resulted in various recorded heron deaths: Langdale (1897) discussed a case where a heron choked on a frog, Cottam (1938) recorded a heron that died while trying to swallow a snake, and various additional cases have been reported where herons have died after trying to eat big fish like carp (e.g., Skead 1981). In January 1988, two dead Great blue herons A. herodias were discovered in the San Francisco Bay area of California, and in both instances the tail of a Pacific lamprey Entosphenus tridentata was projecting from the heron’s bill (Wolf & Jones 1989) [the two photos shown here, from Wolf & Jones (1989), both show the same heron]. The lampreys were 57.6 and 61.9 cm long respectively. Dissection revealed that, in both cases, the lampreys had been killed prior to swallowing (they had not, therefore, injured the herons during the attempting swallowings), and had gotten stuck in the oesophagus anterior to the proventriculus. The great girth of the lampreys meant that, in both cases, the heron’s glottis had been kept closed for too long, and death by suffocation was the result. Wolf & Jones (1989) further noted the possibility that the copious mucus secreted by the lampreys might have exacerbated the situation.
Encounters between Great blue herons and large lampreys are presumably not that uncommon, as hinted at by the discovery – in relatively close proximity – of the two Californian individuals discussed here. Indeed, the various reports of choking in large herons “suggest that death caused by attempted ingestion of large or unwieldy prey by Great blue herons may be an important factor when considering adult mortality and population dynamics of this and similar species” (Wolf & Jones 1989, p. 484).
Mobile phones, medals, a doll’s legs, an entire army… is there anything a gull won’t swallow?
On to some cases that actually don’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.
Caption: Herring gulls photographed around the shores of the southern UK. Images: Darren Naish.
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…
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.
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 below), and another one had swallowed a whole mobile phone [shown below] (Camphuysen et al. 2008).
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.
And we end there. There was originally another article in the series: it discussed a case in which a pet bearded dragon swallowed a toy lizard, passed it out entirely, and survived.. but I can no longer find it and hence haven’t included it here. For those of you who remember this series of articles the first time round, I hope you’ve enjoyed seeing them again. For those of you seeing these for the first time: they are of course the tip of the iceberg, there are sooo many other cases!
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.
Clark, R. J. 1967. Centipede in stomach of young Vipera ammodytes meridionalis. Copeia 1967, 224.
Cottam, C. 1938. A fatal combat between heron and snake. Wilson Bulletin 50, 140.
Holte, A. E. & Houck, M. A. 2000. Juvenile Greater roadrunner (Cuculidae) killed by choking on a Texas horned lizard (Phrynosomatidae). The Southwestern Naturalist 45, 74-76.
Kirschner, A., Müller, T. & Seufer, H. 1996. Faszination Warane. Kirschner & Seufer Verlag, Keltern-Weiler.
Klauber, L. M. 1982. Rattlesnakes: Their Habits, Life Histories, and Influence on Mankind. University of California Press, Berkeley, Los Angeles, and London.
Langdale, H. M. 1897. Heron choked by a frog. Zoologist 1, 572.
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.
Ramírez-Bautista, A. & Uribe, Z. 1992. Trimorphodon biscutatus (Lyre snake): predation fatality. Herpetological Review 23, 82.
Skead, D. M. 1981. Goliath heron chokes on carp. Bokmakierie 33, 51.
Wolf, B. O. & Jones, S. L. 1989. Great blue heron deaths caused by predation on Pacific lamprey. The Condor 91, 482-484.
