Laura Erickson's For the Birds

Monday, November 27, 2017

Cardinal feeding goldfish redux

Last week on Facebook, a lot of my friends were sharing a short video, on a National Geographic webpage, of a cardinal in Illinois feeding goldfish in a backyard pond. The video had been posted on YouTube in 2010, taken during summer, when adult cardinals are feeding their own young and when some individuals molt all their head feathers—this male cardinal’s head was completely bald.


This was news to a lot of people, but I’m old enough to remember an identical story, except for the YouTube video, from college ornithology. Our textbook, The Life of Birds, by Joel Carl Welty, which was a 2nd edition dated 1975, included a black-and-white photo of a cardinal feeding fish in a pond. It was captioned:
Sometimes the urge to feed transcends species, even class boundaries. This Cardinal was discovered feeding an adopted “brood,” of goldfish. Photo by Paul Lemmons, Shelby, N.C.
Photos from that case also popped up in other textbooks and popular books about birds. National Geographic’s own book, Song and Garden Birds from 1964 included the exact same photo published in Welty, this one captioned:
Come and get it! Hungry goldfish crowd the edge of a backyard pool in North Carolina as a cardinal passes out tidbits of food. For days the bird followed this strange routine. Alighting on the pool fence, he chirped. As the seven goldfish gathered, he fluttered down and began to feed them. In their eagerness they almost leaped from the water. Food gone, the bird flew off for more. Perhaps this foster parent had lost his own brood.
Oddly enough, National Geographic doesn’t make reference to their own publication on that YouTube video, even as they asked scientists what they thought about the more recent occurrence. One of them, Robert Mulvihill, an ornithologist at the National Aviary in Pittsburgh, Pennsylvania, mentioned the earlier case, or at least that one of National Geographic Books’ competitors, the LIFE Nature Library books from the 1960s, ran a black-and-white photograph of a cardinal feeding a goldfish. Again, no one thought to look through National Geographic’s own publications.

When National Geographic asked various ornithologists, “Why would a bird feed an entirely different species,” Princeton biologist Christina Riehl had the best response.
“My best guess is that the appearance of the goldfish’s open mouth at the surface of the water is just similar enough in size and shape to the open mouth of a baby bird that it triggers the instinct in the adult bird to provide food to it,” says Riehl.
Nestlings tend to have vibrantly colored mouths, often bright red and yellow. This acts like a bull’s-eye for the parents—a visual cue that says “Feed me here! 
“It’s an amazing demonstration of how simple stimuli can trigger very hardwired behaviors, even in situations that seem obviously wrong to us,” she says.
Scientific as her words were, I return to Joel Carl Welty for the final words, which I’ve quoted many times on past For the Birds programs:
Perhaps the zenith of interspecific feeding of young is represented by a North Carolina Cardinal, Richmondena cardinalis, that was observed for several days feeding goldfish in a garden pool. As the goldfish crowded to the edge of the pool with their open mouths, the Cardinal, standing on the pool’s edge, expertly delivered mouthfuls of worms to them! One can only guess how such a strange association arose, but it seems likely that the Cardinal, bereft of its young, approached the pool to drink, and was met by gaping goldfish accustomed to being fed by humans. The two instinctive appetites, one to feed, the other to be fed, magnetically attracted each other, and a temporary, satisfying bond was set up.
Some past For the Birds programs about this. On newer programs, transcripts are usually linked on the related blog post.