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When blackbirds get sick, it takes weeks for them to recover

Blackbirds, a common sight in many regions, carry with them a secret burden, one that may be more threatening than expected. 

In a study from Lund University, biologists investigated the effects of diseases on blackbirds. The findings challenge prior assumptions and shedding new light on the everyday struggles faced by wild animals.

How the research was conducted 

For the study, birds were subjected to a simulated bacterial infection, a strategy devised to spur their immune responses. 

This allowed researchers to measure and compare their activity levels against those of birds that did not undergo immune system stimulation. The team used miniature data loggers to meticulously track the birds over several weeks.

What the researchers learned 

“We found that the birds whose immune system was stimulated had reduced activity for three weeks, which is much longer than we expected,” said Arne Hegemann, the lead biologist of the study.

“We could also see that the ‘sick’ blackbirds stopped their activities almost an hour earlier in the evenings compared to the control group.”

Significant impacts

It’s a revelation that stands in stark contrast to previously held beliefs in the scientific community. Prior to this, it was widely assumed that the effects of a compromised immune system in birds would only take a day or two to dissipate. 

However, this research shows that not only does it take birds a significantly longer period to recover, but the disease also curtails the duration of their daily activity, rather than diminishing the intensity of activity throughout the day.

Study implications 

“First of all, it is important to understand what happens to wild animals when they are affected by disease. Even mild ailments and short disease spans can have far-reaching consequences for animals, not least because it affects their everyday life,” said Hegemann.

An intriguing yet unresolved question from the study pertains to the exact nature of the birds’ reduced activity. Were they resting or simply remaining stationary? One thing, however, was clear – sick blackbirds turned in for the night considerably earlier.

Greater consequences

“The difference is that when we humans are sick and have symptoms such as fever, reduced appetite or body pain, we may stay at home for a day or two and then return to normal life. Wild animals have the same symptoms but for them the consequences are greater,” explained Hegemann.

“If small birds get sick and have 45 minutes less time per day to look for food, it can be the difference between life and death for both them and their young ones.”

The study not only improves our understanding of the impact of disease on blackbirds but also raises awareness about the unseen trials faced by wildlife on a daily basis.

More about blackbirds

Blackbirds are more than just common garden birds; they play a significant role in ecosystems by controlling insect populations.

Physical characteristics

Males are easily recognizable by their all-black plumage and bright yellow eyes, as well as a yellow-orange beak. In contrast, females have a brown body with a slightly rufous hue on the chest and throat. Their beaks are brownish-pink, and they have a faint mottled pattern.

Habitat and distribution

Blackbirds are primarily found across Europe, Asia, and North Africa. They have also been introduced to Australia and New Zealand. They are versatile in terms of habitat, thriving in woods, gardens, parks, and hedges.

While they are generally not migratory, blackbirds in the colder regions of Europe and Asia will move south to warmer areas during the winter months.


These birds are omnivorous. Their diet mainly consists of insects, worms, and berries, but they also feed on fruits, seeds, and other small creatures.

Behavior and breeding

Blackbirds are known for their melodious songs, especially the males, who sing from high perches to mark their territory and attract females.

They usually breed between March and July. The female builds the nest, which is often a cup shape made of grass and mud.

Typically, a pair of blackbirds will produce 2-3 broods a year, with each brood consisting of 3-5 eggs.


One of the most distinguishable features of the blackbird is its song. The male’s melodious and varied song can often be heard during early morning and late evening, especially during the breeding season. Their song is known to be pleasing to the ear.

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