Bird feeding helps small birds fight infection

Date:
April 18, 2023
Source:
Lund University
Summary:
Seeds and fat balls do more than just fill small birds'
stomachs. New research from Lund University in Sweden shows that
feeding during the wintertime causes birds to be healthier, since
they do not have to expend as much energy fighting infections.


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FULL STORY ========================================================================== Seeds and fat balls do more than just fill small birds' stomachs. New
research from Lund University in Sweden shows that feeding during the wintertime causes birds to be healthier, since they do not have to expend
as much energy fighting infections.


==========================================================================
A small change in body temperature can be fatal for humans. Small birds, meanwhile, lower their body temperature at night by several degrees
during the winter. Just like us, the birds attempt to save energy when
it is cold. If they are exposed to infection, the body's first reaction
is to raise its temperature, which clashes with the bird's simultaneous
need to save energy by lowering body temperature.

"We investigated how access to food during winter affected the balancing
act between maintaining a low body temperature in order to save energy,
and the possibility of raising body temperature in order to fight
infection," says Hannah Watson, biologist Lund University.

The study shows that birds who were fed during the winter did not need to
lower their body temperature as much at night as birds who did not have
access to feeding tables. They had gathered enough energy to survive a
winter night in spite of a having higher body temperature.

When the birds were exposed to a simulated infection, all the birds had essentially the same temperature during a fever. Instead of conserving
energy to survive the winter, the birds without access to extra food
were forced to use more energy in order to raise their body temperature
high enough to battle infection.

"We had expected to find that the birds that had access to birdfeeders
would have more energy to fight an infection, and that as a result they
would exhibit a stronger fever response. Our results, however, show the opposite -- birds that did not have access to a reliable source of food
had the strongest reaction to infection. This enabled them to reach the
same fever temperature as the birds with extra food," says Hannah Watson.

Climate change and human activity are having an ever-increasing impact
on animals. Wild animals come into contact with new pathogens that they
have never encountered before. Bird feeding, then, can have positive
and negative effects.

Birds that visit feeding tables are exposed to more infection because of
the spread of pathogens, but this could make their immune defences more tolerant to a new infection. It is therefore important, the researchers
argue, to understand the factors that affect animals' capacity to put
up an effective immune response -- access to food during winter being
one such example.

"A lot of people like to feed the birds. Our study shows that this can
have a positive effect on the capacity of our small birds to fight an infection," concludes Hannah Watson.

* RELATED_TOPICS
o Plants_&_Animals
# Birds # Nature # Bird_Flu_Research # Zoology #
Marine_Biology # Bacteria # Animals # Agriculture_and_Food
* RELATED_TERMS
o Hawk o Seed_predation o Hummingbird o Owl o Toucan o
Bird_intelligence o Bird o Dodo_and_related_birds

========================================================================== Story Source: Materials provided by Lund_University. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Hannah Watson, Jan‐AAke Nilsson, Johan
F. Nilsson. Thermoregulatory
costs of the innate immune response are modulated by winter food
availability in a small passerine. Journal of Animal Ecology,
2023; DOI: 10.1111/1365-2656.13914 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/04/230418101422.htm

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