How do birds regulate their internal body heat in summer and winter? Adaptations to maintain body heat either behavioral or physical adaptations.

1. Avian Thermoregulation
PreparedBy:
YAMNA ANWER

2. THERMOREGULATION
(THERMO-HEAT; REGULATION-MAINTENANCE)
 Thermoregulation is the ability of an organism to
keep its body temperature within certain
boundaries, even when the surrounding
temperature is very different.
 In other words, maintenance of body heat within a
acceptable range according to the
environment.

3. Animals can be divided into two groups based on how
they regulate body temperature:
 Endotherms generate most of the heat they need
internally. When it's cold out, they increase
metabolic heat production to keep their body
temperature constant. Because of this, the internal
body temperature of an endotherm is more or less
independent of the temperature of the
environment.

4.  Ectotherms, on the other hand, body temperature
mainly depends on external heat sources. That is,
ectotherm body temperature rises and falls along
with the temperature of the surrounding
environment. Although ectotherms do generate
some metabolic heat—like all living things—
ectotherms can't increase this heat production to
maintain a specific internal temperature.

5. HOW DO BIRDS KEEP COOL IN SUMMER?
Heat can be lost in a variety of ways. Four normal
methods of heat loss are listed below. Birds modify
their behaviour to stay in the ‘thermoneutral zone’.
1) Radiation
2) Conduction
3) Convection
4) Evaporation

6.  Radiation: Radiation is the transfer of heat from a
warmer object to a cooler one by infrared radiation,
that is, without direct contact.
 Convection: Convection is the transfer of heat
through the movement of air or liquid.

7.  Conduction: Heat can be transferred between two
objects in direct contact by means of conduction.
Conduction of heat between your skin and nearby
air or water is aided by convection.
 Evaporation: Vaporization of water from a surface
leads to loss of heat.

8. ADAPTATIONS
 Birds have adaptations—features that arose by
natural selection—that help them maintain a
healthy body temperature.
 These adaptations can be behavioral, anatomical,
or physiological.
 Some adaptations increase heat production when
it’s cold.
 Others increase or decrease exchange of heat with
the environment.

9. BEHAVIORAL ADAPTATIONS IN SUMMER
BathingSeeking Shade
Less Solar Radiation Migration

10. Spreading FeathersUrohydrosis Panting
Activity Level Soaring

11. PHYSICAL ADAPTATIONS IN SUMMER
Bare SkinBill Size
Respiration Rate

12. HOW DO BIRDS KEEP WARM IN WINTER?
Endotherms have various ways of increasing
metabolic heat production, or thermogenesis, in
response to cold environments.
 Shivering: One way to produce metabolic heat is
through muscle contraction—for example, if you
shiver uncontrollably when you're very cold.
Shivering increase muscle activity and thus boost
heat production.

13.  Torpor: Many birds will enter torpor to conserve
energy during cold winter nights. Torpor is a state of
reduced metabolism when the body temperature is
lowered, therefore requiring fewer calories to
maintain the proper heat.

14.  Circulatory Mechanisms: The body's surface is
the main site for heat exchange with the
environment. Controlling the flow of blood to the
skin is an important way to control the rate of heat
loss to—or gain from—the surroundings.
Vasoconstriction
Vasodilation

15.  Countercurrent Heat Exchange: Many birds have
countercurrent heat exchangers, circulatory
adaptations that allow heat to be transferred from
blood vessels containing warmer blood to those
containing cooler blood

16.  Insulation: Birds use feathers or fur, to trap a layer
of air next to the skin and reduce heat transfer to
the environment. In cold weather, birds fluff their
feathers to thicken the insulating layer.

17. BEHAVIORAL ADAPTATIONS IN WINTER
Sunning or Basking
Tucking Roosting or Huddling