A great many birds eat a great many bugs: this is something that, in general, we already know. But just how much do they eat? Empirical figures are hard to come by — but according to a new estimate, published in the journal The Science of Nature, the total figure is truly breathtaking, roughly equivalent to the weight of meat and fish consumed each year by humans. Calculated by researchers led by biologist Martin Nyffeler of Switzerland’s University of Basel, the estimate draws upon earlier studies describing what each bird species eats, how much energy they require, and how many of them there are. Nyffeler’s team concludes that the total biomass of wild bird-consumed insects amounts to some 400 million tons.
As aforementioned, that’s about as much animal flesh as is eaten by people. Or, to make another comparison, Nyffeler’s team puts the weight of all those insect-eating birds together weigh at 3 million tons: on average, then, individual birds consume more than 100 times their own body weight in bugs.
The figure underscores the magnitude of ecosystem services provided by insectivorous birds, says Nyffeler; many of those bugs are considered pests, and predation helps regulate their populations and prevent outbreaks. At a more subtle ecological level, predation helps maintain dynamics that promote long-term species richness and abundance.
Putting a monetary value on this extraodinary labor is difficult — no global estimate exists, though various studies give locale-specific figures, such as $4,000 per hectare of enhanced production in Jamaican coffee plantations or nearly $1,500 per kilometer of worm control in northwestern U.S. commercial forests — but the figure, says Nyffeler, is undoubtedly vast.
Source: Anthropocene Magazine, August 1, 2018