Officially, it is autumn. For humans, this often means staying at home and taking some rest after the summer heat. Conversely, for many animals, it is a season of intense preparation for the approaching winter. From deer to birds, and passing through bears, many species are driven by the shortening of days to enter a frenzied mode of food collection, partner searching, and other survival activities. The study of such behaviors in wild animals can give scientists an insight into how they have adapted to face environmental challenges — such as glacial temperatures — and how such resilience can help them cope with future challenges, such as the temperature rise due to climate change. For members of the deer family — including its largest species, the moose — autumn rhymes with reproduction. From September to mid-October, male moose, otherwise solitary, a species widespread in the north of the United States, Canada, Alaska, and northern Europe, seek out other males in order to fight for access to females. A testosterone surge causes the loss of the soft, furry antler covering of moose, called velvet, and transforms them into sharp weapons that they will wield in combat. Research conducted over nearly 40 years in Alaska's Denali National Park has shown that these victorious males — generally the largest and highest-ranking — are responsible for 88% of the matings. Females give birth in the spring, generally starting from the end of May. As birds fly south for the winter, several species consider autumn as a refueling stage. After leaving the northwest and central-west of the United States, for example, grebes gather in large numbers to feed and molt at Mono Lake in California and the Great Salt Lake in Utah. Among the other species that make a stop are Franklin's gulls in the great plains, mallards in the Great Lakes, and sandpipers and other shorebirds on various beaches. Sandpipers, which migrate annually from the Arctic to the Southern Hemisphere and vice versa, will fly 2,400 kilometers in one wingbeat, then stop to rest, feed, and molt at these places and return faithfully every year. In autumn, North American bears actively participate in a process called hyperphagia. They eat and drink as much as possible to gain weight before their long winter hibernation. While humans would suffer serious health problems if they attempted this exercise, a recent study published in the section Communications Biology of the journal Nature has revealed that grizzly bear genes are regulated differently in autumn and winter to cope with such physical efforts. For example, during hibernation, their genes express in a way that reduces their sensitivity to insulin, so that their blood sugar level remains at a normal level and is not used by the brain, which needs it during a long sleep. This also allows large mammals to metabolize fats during hibernation, something that humans resting are unable to do, notes the study co-author Joanna Kelley, an evolutionary geneticist at Washington State University. There are about 5,000 species of ladybugs and many of them, including the invasive Asian multicolored ladybug species in North America, "will eat thousands of aphids and soft-bodied prey" as autumn approaches, explains Mike Raupp, an entomologist at the University of Maryland. After this lavish banquet, the insects will gather, sometimes in large masses, where they will enter a dormant state to wait for the long winter. Ladybugs tend to crawl into rock outcrop crevices, but sometimes gather around nearby homes, thinking "they resemble a large and magnificent rock wall," Raupp specifies. This ladybug often goes unnoticed by predators, but if a hungry animal discovers one of these groups and is not repelled by their bright colors, the insects can then trigger a bleeding reflex. A foul-smelling hemolymph, also known as bug blood, escapes and causes the predator to feel nauseated, he says. While other birds are busy flying south for the winter, the Nuttall's cottontail (Phalaenoptilus nuttallii) of western North America and Mexico is resting. These nocturnal members of the Caprimulgidae family are the only known bird species to enter a torpor, a state similar to hibernation, during which animals can lower their body temperature to 5 degrees Celsius. The Nuttall's cottontail "hibernates" as it nests, on the ground, where its brown, speckled camouflage makes it almost invisible. Like mammals, it is at its maximum weight when it enters its torpor, explains Mark Brigham, a biologist at the University of Regina in Saskatchewan. In his research in Arizona, Brigham discovered that Nuttall's cottontails that hibernate face southwest. The afternoon sun will therefore help them warm up in addition to their body metabolism, he says. Brigham co-authored a study published this year in the journal Oecologia, which revealed that the average duration of the Nuttall's cottontail torpor was five days, but that this particular bird had slept 45 days.