A new study from UCLA has found that some urban birds may actually be less afraid of people following the coronavirus pandemic that saw millions of Americans spending more time indoors and less time in crowded public squares.
The findings came as a shock to UCLA researchers who expected the opposite to be true. The researchers initially theorized that the return of humans into the public space would scare off birds that had grown accustomed to having it for themselves.
The study involved dark-eyed juncos, which have thrived on the campus of UCLA for around 20 years. Scientists have been studying fear and aggression in the campus birds for several years, dating back to several years before the pandemic.
When cases COVID-19 swept across the world and led to a shift in education, prompting most universities to switch to online instruction, the number of people on UCLA’s campus dropped significantly. The nearly empty campus gave researchers a unique chance to study the behavior of the birds with fewer people were around.
Juncos mostly feed and nest on the ground and come in close contact with humans often — now they had the place mostly to themselves.
The initial theory was that the birds, now presented with having the campus essentially to themselves, would start to revert to behavior seen in their “wilder” relatives that don’t have regular interactions with people.
Those wild birds typically won’t let humans get within 11.5 feet before flying away. Before the pandemic, the campus birds would allow humans to get about 5.5 feet from them before flying away. That same level of fear response remained in place when the campus was mostly empty.
But once it became busy again, that’s when the birds started acting differently.
The study indicates that once campus life returned to normal, the birds acted “drastically less fearful” of humans. Humans were able to get as close as 3.25 feet, or 39 inches, before the birds would become fearful and fly away.
The findings “completely defied their expectations,” UCLA officials said.
Biologists apparently have two working theories as to how wild birds get used to living around people in densely populated areas. The first is called habituation: birds that encounter large numbers of humans become less fearful over time, and birds that don’t come in contact with humans become more fearful.
The other theory is that birds that live in cities are there in part because they are already less fearful of humans to begin with.
The findings of the UCLA study goes against both of those existing theories.
“If less fearful birds had chosen to live on campus in the first place, we would have expected their fear response to be essentially unchanged. If they were habituated, we would have thought they’d become more fearful during the closure and then less fearful after, or not shift their behavior at all,” said Eleanor Diamant, the lead researcher. “But these birds didn’t shift fear response with humans absent and they shifted toward much less fearful after humans came back.”
Pamela Yeh is a UCLA professor of ecology and evolutionary biology and was the senior author of the study.
Yeh said the findings could be explained in two possible ways. It’s possible that once an animal’s fear response gets “tamped down,” new events will only tamp it down further. It could also mean that the fear response tends to just eventually return to its normal level after being lowered. Additional observation of the junco population would likely help researchers determine which is the case.
“The effects of humans on wild animals are really complex and what we expect isn’t always what we get,” Yeh said. “So our research shows both the complexity of the juncos’ response to humans and of their response to other changes.”
Diamant echoed that sentiment, saying, “there’s so much complex animal behavior that we don’t know about, even though they are our neighbors in cities.”
She said unexpected events like the pandemic really “bring into focus” what we often don’t know or understand about animals because the opportunity to study and test them under unusual conditions simply don’t happen.
The study could also provide hope for other species of North America birds that have seen dramatic population reductions, due in large part to human disturbances in their natural habitats. UCLA officials say some estimates peg the number of lost birds at around 3 billion in North America alone since 1970, including about 175 million of the dark-eyed juncos featured in this study.