1. Energy Transfer through Food Webs
Objective:
Understand how energy is transferred through a food chain or web
Be able to use a dichotomous key
Be able to construct the food web of barn owl
Be able to estimate the producer biomass needed to support a barn owl for one year

2. Owl Pellet Safety Wearing gloves Washing hands after use
Allergic to pet: contains hair of the prey
Pellets: heat sterilized

3. Terminologies Species → Population → Community Autotrophs/ producers
Consumers
Primary- herbivores
Secondary-carnivores
Tertiary)-omnivores
Detrivores /
decomposers :
recycles nutrients

4. Background Food chain:
Energy moves through a community as organisms feed on one another.
Simplified, linear representation of energy flow

5. Food web:
complex and realistic
shows all possible flow path

6. First Law of Thermodynamics:
Conservation of energy
Quantity and quality of energy transferred
efficiency
heat
Second Law of Thermodynamics:
Entropy: degree of disorder within a system

7. Energy Flow

8. Phytoplankton/Producers
Trophic Structure
Eagle/
Top Predator
(0.1 Calories)
Chinook Salmon/
Tertiary consumer
(1 Calories)
School of minnows/
Secondary consumer
(10 Calories)
Zooplankton/
Primary Consumers
(100 Calories)
Phytoplankton/Producers
(1000 Calories)
Pyramid of Number
Pyramid of Biomass
Pyramid of Energy
Example:

10. Trophic Level: position in the feeding hierarchy Pyramid of Biomass Pyramid of Energy

11. Constructing a food web and pyramid of biomass for Barn Owl (Tyto alba)
Top predator
Nocturnal
Hunt at night
Have an excellent vision
Acute sense of hearing
Feathery depressions around eyes
Swallow whole prey
Digest only fleshy parts
Indigestible portions of prey : PELLETS or CASTING

12. Needs 6-12 hours to form casting
Casting become a home and source of food for a variety of insects
Prey:10-15 per night
Herbivores: Rodentia eg: mice, voles, rats, pocket gophers.
Carnivores: Insectivora eg: moles, shrews
Life expectancy: 7-8 years
Cosmopolitan Species

13. Procedure Dissect an owl casting
Identify the animal remains contained within the casting using a DICHOTOMOUS KEY
INSECTIVORA :No Gap(Diastema) between incisors and cheek teeth
Zygomatic Arch
RODENTIA: Gap (Diastema) between incisors and cheek teeth
Infraorbital Canal

14. Hypothesis
H1:the number of producers that it takes to support a barn owl with a diet consisting Rodent is higher than a diet consisting of Insectivores
H0:the number of producers that it takes to support a barn owl with a diet consisting Rodent is NOT higher than a diet consisting of Insectivores
Homework : Page 41 through 43
Page 44 (Education Majors Only)