Popcorn for pelagics?

A recent post on Tetrapod Zoology in which blogmaster Darren Naish rails against the well-meaning tradition of feeding bread to ducks got me thinking of another bird-feeding issue: chumming for pelagics.

Westland Petrel by Pablo Caceres Contreras

Westland Petrel by Pablo Caceres Contreras (licensed under Creative Commons)

My pelagic experience is limited, but on a couple of the trips I’ve been on the chum of choice was stale popcorn. This strikes me as insane. Gulls can probably digest almost anything, but the procellariiform birds that are the most sought-after prizes of pelagic excursions (shearwaters, petrels, albatrosses, etc.) have digestive systems adapted to digest protein. Why, other than economy, would we feed them almost pure carbs? The soft parts of popcorn probably disintegrate readily, but what do the hard bits do to the birds’ digestive systems? Given that these are pelagic birds, would we even know if they were dying like flies from popcorn impactions? Has anyone studied this? Talk me down, somebody…

Addendum: Procellariids do ingest some pretty formidable items. Bones, even fish otoliths, are rapidly dissolved by the birds’ digestive acids, but squid beaks (one of the hardest materials in nature) take weeks to break down. Gulls, terns, and many other seabirds can simply barf up indigestible materials, but procellariids have difficulty regurgitating solids (Furness et al. 1984). Combined with relatively small gizzard capacity, this makes them “especially susceptible” to deleterious effects from ingestion of indigestible materials (Azzarello & Van Vleet 1987).

More complex organic molecules require particular enzymes for processing. Just as many adult humans don’t produce the enzyme lactase and must avoid milk products, some birds such as thrushes (Witmer and Martínez del Rio 2001) don’t produce sucrase and must avoid sucrose-rich foods. Given their naturally low-carb diet, would we expect procellariids to produce starch-digesting amylase? If they don’t, does popcorn cause them intestinal distress similar to that suffered by lactose-intolerant humans and sucrose-intolerant thrushes?

But even if procellariids that eat the popcorn we chum with eventually end up barfing it up or breaking it down, is it their best interests or ours to trick them into wasting time and crop space on something that is at best of low nutritional value when more appropriate alternatives are available?

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5 thoughts on “Popcorn for pelagics?

  1. Surely you jest.
    In the great scheme of things. A tiny bit of popcorn when plastics are everywhere for the seabirds to injest seems like a tiny thing. Don’t they eat fish bones?

  2. Mike: Intriguing possibility (I’d certainly follow a trail of buttery popcorn aroma).

    Liz: No, I don’t jest, and don’t call me Shirley. ;>

    The plastics issue is both a weak analogy and a red herring, similar to arguments that attempt to justify other intrusive birding behaviors. The lesser of two evils is still evil, and we do have more appropriate choices for chum (which have their own environmental impacts, of course, but at least the bird impacts are indirect). It shouldn’t be too much to ask that birding tour providers make choices that err on the side of caution, if only out of enlightened self interest.

  3. It was late really late when I made the comment I couldn’t sleep. Sometimes it is hard to consider how many ways we impact the world around us.
    One more thing to worry about.

    Love to you!
    Liz

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