Foraging Ecology

Question 1

Foraging

Answer 1

The process of finding wild food resources

Question 2

What does foraging entail?

Answer 2

Decision making regarding how, when, and where to find food

Question 3

What are some life history constraints on foraging?

Answer 3

Seabirds feed at sea but raise their young onshore

Question 4

Stomach Oil

Answer 4

• Found in the proventriculus of procellariiformes
• Composed of dietary lipids
• Made up of waxes, esters, and triglycerides

Question 5

What is the significance of stomach oil?

Answer 5

• Light
• High caloric density
• Replenishes water reserves

Question 6

Describe the optimal foraging theory

Answer 6

Maximize energy gain to enhance fitness

Question 7

Describe the two foraging strategies of breeding albatrosses

Answer 7

1. Short trips
2. Long trips

Question 8

What is the significance of short foraging trips?

Answer 8

• Energetically beneficial to the chicks
• Energetically costly for adults
• Close to breeding colony

Question 9

What is the significance of long breeding trips?

Answer 9

• Maintain parental body mass
• Lower food delivery rates for chicks

Question 10

Intraspecific competition

Answer 10

Competition for limiting resources during nesting season

Question 11

Interspecific competition

Answer 11

Competition for limiting resources year round (cooperative feeding)

Question 12

How does sexual segregation affect seabird prey and foraging habitat (use Northern Giant Petrals as an example)?

Answer 12

• Females are smaller than males
• Females eat fish, krill
• Males = scavengers ( eat carcasses)

Question 13

Resource partitioning

Answer 13

Different organisms within one ecosystem forage on different prey types in different areas so that there is limited competition for resources

Question 14

What are examples of resource partitioning?

Answer 14

• Crested auklets (upstream), parakeet auklets (middle), least auklets (downstream) forage in different areas of the ocean
• Sexual segregation
• Habitat partitioning

Question 15

Internal constraints to foraging

Answer 15

Physiological limitations such as:
-Flight costs
- Diving costs (ADL)

Question 16

External constraints to foraging

Answer 16

Factors affecting prey:
- Prey size
- Caloric density
- Predictability
- Accessibility
- Aggregation of prey

Question 17

What oceanographic features can affect foraging movement?

Answer 17

• Fronts
• Eddies
• Upwellings

Question 18

How can oceanographic features affect foraging movement?

Answer 18

Oceanographic features –> Aggregate prey –> Attract foraging predators

Question 19

Fronts

Answer 19

Regions with enhanced gradients of hydrographic properties (temperature, salinity, nutrients)

Question 20

Oceanographic Hotspots

Answer 20

• Upwelling
• Sea mounts (rise in elevation of the sea floor)
• Convergence zones
• Shelf / coastal areas

Question 21

Convergence zones

Answer 21

Different water masses come together resulting in downwelling which causes prey items to float and aggregate in surface waters

Question 22

How are oceanographic hotspots related to productivity?

Answer 22

Productivity generally increases near an oceanographic hotspot

Question 23

Coastal upwelling

Answer 23

• Surface water = being forced offshore by prevailing winds (Coriolis effect: water moves perpendicular to direction of wind)
• Brings cold, nutrient rich water to the surface (photic zone: where photosynthesis occurs)
• Productivity = increased

Question 24

Describe the general conditions of coastal upwelling systems

Answer 24

• Low temperatures
• High O2 content
• High nutrient contents

Question 25

Cyclonic eddies

Answer 25

- Counter clockwise - Cold core eddies - Northern hemisphere - Cold water is upwelled - Prey is aggregated

Question 26

Anticyclonic eddies

Answer 26

- Clockwise - Warm core eddies - Cold water is downwelled

Question 27

What meso-scale oceanographic features can be measured from space?

Answer 27

- Satellite altimetry - Current measurements - Chlorophyll measurements

Question 28

Satellite altimetry

Answer 28

Measures height of sea surface

Question 29

Current measurements

Answer 29

Determines how rings of eddies are rotating

Question 30

Chlorophyll measurements

Answer 30

Measurement of biological productivity (more chlorophyl = higher productivity)

Question 31

Describe how Great Frigate birds utilize eddies

Answer 31

Target the edge of eddies where prey aggregated at the surface *Frigate birds cannot land on the water*

Question 32

Gulf Stream Rings

Answer 32

- As Gulf Stream moves offshore meanders form - Meanders drive formation of eddies (below Gulf Stream) - Eddies = cold core (cyclonic) - Results in upwelling

Question 33

Describe a fine scale oceanographic feature in Phalaropes

Answer 33

- Surface feeders - Spinning behavior - Generates upwelling of prey which is aggregated at the bottom *Only effective in shallow waters*

Question 34

Copepods

Answer 34

- Phalarope prey - Lots of lipids - Located at depth of 50 to 150 m in the Bay of Fundy *Why is this a problem*

Question 35

Bay of Fundy

Answer 35

- Largest tidal currents in the world - Tidal currents hit ledges creating vertical mixing - Creates upwelling and fast current speeds (above ledges) - Low surface temperatures (due to upwelling) - Aggregates copepods in surface water

Question 36

How do oceanographic features affect diving birds (ex King Penguins)?

Answer 36

- Associated with fronts - Feed on prey aggregated in frontal regions

Question 37

How are foraging skills learned in seabirds?

Answer 37

- Acquired gradually - Long period after fledging - Breeding is not attempted until foraging is successfully learned - Must learn to recognize physical biotic features of ocean as indicators of food

Question 38

How does age affect foraging proficiency?

Answer 38

- Adult birds = more proficient foragers than juveniles - Maturation = delayed until foraging skills = acquired - Foraging proficiency = gradually increased with age

Question 39

El Niño

Answer 39

- Trade winds (east to west) weaken - Warm water is pushed East - Pacific Jet stream moves south - Results in little to no upwelling of nutrient rich cold water

Question 40

La Niña

Answer 40

- Trade winds are stronger than usual - Warm water is pushed West - Pacific Jet Stream moves North - Results in increased upwelling but warmer temperatures

Question 41

Transition zone chlorophyl front (TZCF)

Answer 41

- Cold more productive waters in North - Warmer less productive water in South - Important foraging area for albatrosses

Question 42

How does the TZCF affect albatross breeding seasons?

Answer 42

- Location is further South during breeding season (closer to foraging area = shorter distance to travel) - North = longer distance to travel

Question 43

How does El Niño affect oceanographic features?

Answer 43

- Temperatures cool - North Pacific Gyre contracts - TZCF = further South (less distance for albatrosses to travel while foraging) - High reproductive success

Question 44

How does La Niña affect oceanographic features?

Answer 44

- Temperatures warm - North Pacific Gyre expands - TZCF = further North (larger distance for albatrosses to travel while foraging) - Low reproductive success

Question 45

How is albatross reproduction affected by La Niña?

Answer 45

- Reproduction decreases - TZCF = far North - Less food goes to chicks (longer foraging trips) - High sea surface temperatures (poor foraging conditions)