How is the COVID-19 lockdown affecting wildlife?

When the cat's away, the mice will play … or

Or rather, should we say, when humans are confined, wildlife is thriving? The lockdown measures implemented in response to the pandemic COVID-19 is prompting people to avoid contact with the outside world and to limit their movements, which has consequences for animals. But does this necessarily mean more freedom for wildlife? Not necessarily.  

Quarantine and lockdown measures have brought the world to a standstill for several weeks now. Human activity has been reduced to faint whispers, and cities are gradually falling silent. With most people confined to their homes, the usual clamor of daily life and traffic has given way to a profound emptiness and an overwhelming calm. And wildlife has already responded. What changes can we expect?

The internet is flooded with information about wildlife reclaiming our cities. Not all of it is factual, but overall, animals in and around cities are becoming bolder and venturing out onto the streets. But these new habits aren’t always positive.

The interaction between human activity and wildlife, and the impact of that activity, are complex and difficult to predict. Humans can affect their environment in various ways. Sensory pollution—which alters light, sound, and the chemical composition of the environment—is one such form of disturbance. It affects the health of species—that is, their mortality and reproductive capacity—through both physiological effects and effects that cause behavioral changes via three mechanisms: masking, distraction, and deception.

Masking is the process by which sensory pollution affects an organism’s ability to detect or discriminate a target. In the case of distraction, sensory pollution draws an animal’s attention away from the task at hand. Finally, deception occurs when a sensory pollutant leads animals in the wrong direction or toward the wrong target.

So what changes can we expect for animals while humans are confined to their homes?

Noise pollution

One thing is certain: during the lockdown, noise pollution—one of the main environmental risks to animal and human health—decreased significantly, which has had numerous repercussions.

The survival of many species depends on their sense of hearing. Amphibians, birds, insects, and mammals rely on sound to convey essential information, such as mating calls or warning signals. For example, fish larvae find their way home by following the sounds of coral reefs, and owls use acoustic signals to locate their prey. All of these fundamental behaviors are threatened if animals cannot hear properly.

An analysis of more than 109 terrestrial and aquatic animal species is unequivocal. Under normal circumstances, human-generated noise disturbs everything from the smallest insect to the largest marine mammal. It goes without saying that noise pollution affects the hunting behavior of bats, which rely on ultrasonic signals to locate their prey, but the effect may be more subtle in other species.

For some birds, for example, noise affects their health and the growth of their offspring. Chicks exposed to high levels of background noise are smaller than their counterparts in quiet environments. High background noise also affects blood glucocorticoid levels, likely to prevent the negative effects of chronically elevated levels on the body.

In addition, noise also affects intra- and inter-species communication. A city bird tends to sing louder and at a higher pitch than its rural counterpart, which affects the perceived quality of their songs.

Quieting measures and noise reduction can therefore influence several factors. With reduced traffic noise, bats, birds, and other animals can communicate more effectively, which may result in better opportunities

mating.

Some birds that used to avoid excessively noisy areas during their migration—which resulted in a reduction in the species’ genetic diversity—are now able to find their fellow birds. Walls of sound divide populations. With this quiet, genetic mixing will provide a new lease on life and the vitality needed by certain populations.

Decrease in human trafficking

Otherwise, the reduction in road traffic will clearly have an impact on wildlife. For example, 37,000 barn owls are killed each year on France’s 11,000 kilometers of highways. Just a few weeks with fewer cars—especially during school vacations and the May holidays—will be enough to save lives, particularly as animals emerge from hibernation and during the birthing season.

And that’s not even taking into account the reduction in air pollution. In fact, dogs, cats, and wildlife are sentient beings just as sensitive to air pollution as humans are. One of the few studies on the subject has shown that dogs exposed to Mexico City’s polluted air exhibit increased brain inflammation and abnormalities associated with diseases such as Alzheimer’s, compared to dogs living in less polluted cities.

The Consequences of Lifting Lockdown Restrictions

Pollution is considered the third or fourth leading cause of biodiversity loss, and some species are directly threatened by air pollution.

However, many urban animals have grown accustomed to their two-legged neighbors and sometimes depend on them for food, for example. The closure of parks and riverbanks, or the decline in tourism, will force animals to find new sources of food.

However, we must be particularly mindful of the consequences of lifting lockdown restrictions, especially during this breeding season. Many animals will have chosen nesting sites that, once lockdown restrictions are lifted, may prove problematic. Birds and mammals that thought they had chosen a strategically quiet spot will be surprised to find themselves in the midst of traffic that had previously disappeared. For example, the return of beachgoers will put small breeding terns at risk; they may be trampled or disturbed, and they are already quite endangered.

We will therefore need to be particularly vigilant as we return to normal. Changes—whether during lockdown or as restrictions are lifted—will be stressful for wildlife in both cases.

https://vetitude.fr/westnile-pollution-lumineuse-zoonose/