Ants social distance?

black ant on moss next to reservoir
“I could be at the picnic, but I forgot my mask… AGAIN!” Photo by Skyler Ewing on

One early morning at the end of July I decided to explore the handicap trail leading from the Refuge Headquarters. I wanted to see what a young person or someone at wheelchair or stroller height would notice. Eight in the morning outdoors on this trail brings the eternal optimism of a fresh new day wide open to the skies. Walk ten feet and you will have joined a young cotton tail and seen a dozen or more plants and animals within arms reach and grasses taller than myself, with spectacular arrays of vibrating seeds. A monarch butterfly landed on a milkweed so I checked other milkweeds along the path – no monarchs but a commonwealth of animals hosted by this plant – the eponymous milkweed bugs [large] , japanese beetles, dog bane beetles, snails, slugs, dew-spangled spider webs, frog hoppers and then, the pest-of- honor, yellow oleander aphids with their symbiotic ants.

Ants herding aphids - photo by Dorothy Rapp
Ants herding aphids – photo by Dorothy Rapp

These herding ants “milk” the aphids for their excreted honeydew and return the favor by grooming the aphids of parasites and discouraging their predators. Chemicals on ants feet keep the aphids subdued during their ministrations. Some ants carry off aphid eggs for the winter ready to start a new aphid herd next season. What really caught my attention was the number of ants scurrying over leaves, stems or pods and I thought of a recent article describing social distancing in infected ants; no social distancing here! However, this is not where functional distancing might happen. The study showed that experimental fungal infection of forager Lasius niger [aka garden ant] led to a rapid and strategic social distancing. The foragers self-isolated, spending more time away from the colony and nurse ants developed risk-averse behavior, moving their brood further into the nest. Other studies showed that there is increased interaction among cliques – foragers with foragers and nurses with nurses, but not between the two cliques with the collective result that the queen and the next generation were protected.

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The garden ant article also quoted a study finding that house finches avoided “sick” birds that had been injected to become lethargic and the degree of avoidance correlated with the activation level of their immune system. The Cornell Ornithology Laboratory indicates that the devastating mycoplasmal conjunctivitis infection rate of house finches has equilibrated to 5-10%. It would be interesting to know if finch social behavior contributed to this stability in addition to any role played by people modifying feeder station density and sanitation.

Ants on Milkweed, photo by Dorothy Rapp
Ants on Milkweed, photo by Dorothy Rapp

After this refuge visit I researched further into social distancing in animals and, on-line, discovered a burgeoning literature documenting behavioral responses to horizontal infections in animals, inviting comparisons with our own social responses to the current COVID19 situation.

One early visit to the Refuge lifted spirits, captured interest and prompted research to know more – a good day.