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. We previously looked at a rabbit-eating Great grey heron Ardea cinerea here. I’m actually intending to talk about herons and their feeding behaviour at length at some stage; not today though.
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).
For previous articles in the ‘over-enthusiastic swallowing’ series see…
- Roadrunner tries to eat horned lizard. Splits neck open. Dies.
- Snake 195 mm long eats centipede 140 mm long. Centipede too big. Snake dies.
- Perentie tries to swallow echidna. Echidna too spiky, Perentie gets horribly injured. Dies.
Ref – –
Cottam, C. 1938. A fatal combat between heron and snake. Wilson Bulletin 50, 140.
Langdale, H. M. 1897. Heron choked by a frog. Zoologist 1, 572.
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.