A study conducted by researchers at Lund University in Sweden has found that blackbirds, like humans, have a tendency to go to bed earlier when they are sick.
While we know that humans often require bed rest when they are ill, little is known about how illnesses affect wild animals. Arne Hegemann, a researcher at Lund University, explains that smaller animals like birds need to hunt or forage for food daily due to their lack of fat reserves. This means that when they are incapacitated by sickness, they are at a higher risk of predation.
To investigate the impact of illness on wild birds, the researchers captured 45 Eurasian blackbirds and attached accelerometers to them to track their movements. Half of the birds were injected with a compound that mimicked a bacterial infection and suppressed their immune system. All the birds were then monitored for 48 days after release.
The study found that the immune-challenged birds moved 19% less in the 20 days following the injection compared to the control group. This decrease in movement was primarily due to the sick birds resting around an hour earlier in the evening than the healthy birds. However, both groups had similar activity levels during their most active hours.
According to Hegemann, it was previously assumed that sick birds would return to normal behavior within 24 to 48 hours. However, the study revealed that there is a change in behavior for up to three weeks after the injection.
The researchers believe that the decrease in activity could be due to symptoms such as fever, decreased appetite, and body aches experienced by the sick birds while their immune systems are weakened.
The effects of illness may be more severe during certain times of the year, such as the breeding season when blackbirds need to feed their young, or in winter when food availability is reduced. The research team plans to further investigate these seasonal variations.
Unique Insights:
– The study reveals that blackbirds adjust their sleep patterns when they are sick, going to bed earlier in the evening.
– Smaller animals like birds, without fat reserves, are at a higher risk of predation when they are incapacitated by illness.
– The decrease in activity observed in sick birds may be attributed to symptoms such as fever, decreased appetite, and body aches.
– There is a change in behavior for up to three weeks after the birds are injected with the compound that mimics a bacterial infection.
– The impact of illness may be more severe during critical periods such as the breeding season or winter when food availability is limited.
