Last Wednesday night, during a Boston community meeting to address the age-old problem of youngsters raising a ruckus, John Linehan, the president and CEO of Zoo New England, made a curious assertion.
The noisy parties and dirt-bike traffic that have become increasingly common near the zoo as pandemic restrictions have loosened had left the facility’s animals distressed, he said.
It was even possible, he acknowledged, that some had grown too flustered to mate.
As he put it, “We have struggled.”
Since early on in the pandemic, scientists have been attempting to discern the various effects of the pandemic on wildlife across the world. Did you know, for instance, that the reduced traffic noise in the San Francisco Bay Area has led to a shift in song frequency in white-crowned sparrows, according to a study published in Science magazine? Or that Northern Italy’s improved pandemic-era air quality resulted in a boost in egg-laying by the common swift?
But the effects on zoo animals, many of whom reside in urban areas that have undergone significant change during the past year of isolation, appears to remain a largely unexplored frontier.
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The 527-acre Franklin Park, which surrounds the zoo and connects Jamaica Plain, Roxbury, Dorchester, Mattapan, and Roslindale, has been a particular source of recent complaints from residents who say that large gatherings and ATV traffic have made things difficult for many — and that includes the animals.
“While our animals are used to the typical sounds of the city, extremely loud noises, particularly loud, deep bass sounds, impacts the well-being of animals, especially those in proximity to the noise,” Linehan said in a statement to the Globe. The noise is none-too-welcome among the zoo’s employees, either, he added.
The particulars of how this is playing out at the Franklin Park Zoo, alas, remain largely shrouded in mystery. Citing ongoing COVID concerns, a spokeswoman for the facility recently declined a Globe reporter’s request to tour the zoo and speak with zookeepers about how, for instance, the Sardinian dwarf donkeys and Madagascar hissing cockroaches have been faring amid the recent commotion.
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But in recent interviews, a collection of zoologists and biologists said that Linehan’s observations about noise, and its affect on the zoo’s animals, made perfect sense.
“There are a wide variety of things that happen that are not good if you continuously subject an animal to a stressful environment,” said Jeffrey Lucas, a professor in biological sciences at Purdue University. “And noise is stress.”
In the wild, the sudden introduction of new noise sources can have dire consequences. Animals that use mating calls, for instance, are unable to hear their would-be lovers, while those that rely on their ears to avoid predators, like mice or squirrels, become increasingly vulnerable.
For animals in captivity, the effects differ, though they’re not necessarily less significant.
“In the wild, a lot of animals will leave noisy areas — so rabbits might leave because they can’t hear predators, or social animals might leave because they can’t communicate,” said Richard Primack, a professor of biology at Boston University. “Zoo animals don’t have that option.”
Primack compared it to checking into a hotel, only to find that the room next door is throwing an all-night party.
For animals, the experience is no different.
“The next day,” he says, “you’re [going to be] feeling uncomfortable and irritable.”
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Tolerance for noise can vary by species.
Generally speaking, larger animals, like elephants and rhinoceroses — rhinoceri? — are less impacted by noise, according to Ed Hansen, CEO of the American Association of Zoo Keepers, while smaller animals can be more acutely affected.
Though there is the occasional outlier.
“Giraffes,” Hansen notes, “do not take well to noise disturbances.”
At the Franklin Park Zoo, which is currently open to the public with some capacity restrictions, acute changes to an animal’s environment have historically resulted in a number of altered behaviors. The red pandas will pace. The wildebeest will retreat to the far end of their exhibit, away from the source of the noise. And the Baird’s tapirs will make it clear that they’d very much prefer to be indoors.
In fact, said Lucas, the effects of noise can be even more daunting for animals in captivity, who are already dealing with the stress of existing outside the environment in which they’re evolutionarily coded to thrive.
“The fact is, animals are a unit that responds to their environment, and they’ve adapted to respond to specific environments, and what we’re doing is completely screwing up their environments by bringing them into a cage,” Lucas said. “And then by making a lot of noise, we’re making it worse.”
But in the same way that city-dwelling humans eventually grow used to the nightly cascade of car horns and police sirens, animals, too, are adaptable.
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For more than 30 years, Hansen, of the American Association of Zoo Keepers, worked at an Arizona zoo located just a mile from a military aircraft runway, where the animals on site were accustomed to the regular rumble of plane engines.
And as the world’s population emerges from the pandemic, he said, humans and animals alike will be forced to adjust various aspects of their lives.
“It’s just another aspect of COVID,” he said. “I guess we’re all going to learn how to adapt and move forward.”
Dugan Arnett can be reached at dugan.arnett@globe.com.