Niche lab (complete) PDF

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Biodiversity Niche lab...

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Samara Betty 11/13/2020 Professor K. Johnson Biology 115: ecology and evolution laboratory

Feeding Behavior in Wintering Birds

Research question: Do birds at a feeder exhibit different feeding niches? This lab will demonstrate how animals use behavior to avoid competition for scarce resources by observing birds in their natural environment. We will study how seed-eating birds avoid competition by how they use the resources at a feeding station. Objectives: To develop an understanding of behavioral ecology and to gain experience in observing animal behavior in a natural setting Important background information: 

Ecological niche: all the environmental and physiological requirements for an organism to survive, including environmental factors and physiological and behavioral traits



Resources needed for survival are often limited leading to competition between species (interspecific competition) and between different individuals of the same species (intraspecific competition)

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Competitive exclusion principle: If two species compete for the same resource at the same time, one will go extinct

Materials: Binoculars, field guide Procedure: 1. Observe bird feeder on campus. Stay back at least 15 meters, remain as still as possible so that you do not disturb the birds. Observing from inside is ideal. 2. Identify birds seen. This is easiest using a field guide. For each bird- write the common name on a row label on the calculation page at the end of this exercise. Add new species as they appear. 3. There are at least 3 feeding niches around a sunflower seed feeder. Birds may eat seeds while perched on the feeder. They may pick up seeds at the feeder and fly somewhere else to remove the hulls and eat the seeds, or they may feed on the seeds that have fallen on the ground under the feeder. Write brief descriptions, “at feeder”, “away from feeder”, and “on ground” on the column headings in the calculation page. 4. 30 minutes or more- note each bird that visits the feeder. 1-minute intervals, note birds sitting at the feeder at this time, birds feeding on the ground at this time, and birds that have taken a seed and flown away in the past minute. Make a tally mark for each bird in the data table, indicating species and feeding niche for that feeding event. You may count the same bird twice if it is occupying the niche for more than one interval of time. Altogether, you should have at least 30 feeding events recorded. 5. To test null hypothesis that birds occupy feeding niches at random, use data from 3-5 of the most common bird species in your survey. Complete the data table at the end of this

chapter and follow the directions to perform a Chi-square contingency test. Interpret your results by answering the questions.

Table 1: Field observations of bird behavior Feeding Behavior On ground

At feeder

In trees

Species Northern cardinal

1

6

0

Dark eyed junco

0

1

7

Carolina chicadee

8

0

0

House sparrow

2

0

0

Blue jay

0

4

0

Tufted titmouse

1

0

4

1) Interpret results of Chi-square test. If it shows significance, what does this mean in terms of feeding niches for birds at your feeder?

a. Northern cardinal- more dominant feeders; beak design was most likely better suited for direct feeding out of the feeder. b. Dark eyed junco- Passive feeder; avoids conflict by waiting c. Carolina chickadee- Dominant feeders; beak design was most likely better suited for direct feeding out of the feeder. d. House sparrow- Advantageous feeders, willing to settle for scraps; not too fond of seeds used. e. Blue jay- Northern cardinal- more dominant feeders; beak design was most likely better suited for direct feeding out of the feeder. f. Tufted titmouse- Passive feeder; avoids conflict by waiting

2) How does a bird’s beak influence the way it eats sunflower seeds? Do differences in beak shape help to explain any differences in feeding niches you observed? a. For eating sunflower seeds birds ought to have short, thick, and pointed beaks which help them to crack the seeds .The fowls with slim bill might want to eat unshelled seed, as they find trouble in opening the shell. Evolution is one of the major reasons for the change in beak shape and evolution mostly occurs due to competence in the feeding between different genus or species or different animals. It was proved that the social learning is important than the hereditary learning. Therefore, the differences in beak shape is very useful in finding out the differences in feeding niches. 3) Are some species more aggressive in defending a place at the feeder than others? How do less aggressive birds manage to obtain food?

a. some bird species are more aggressive in defending a place at the feeder than the others. Aggressive bird may chase others away from the feeding area. Lesser aggressive avoid the aggressive birds by simply eating the seeds that have fallen to ground. 4) Position of birds eating sunflower seed is the niche dimension we explored in this exercise. In what other ways do birds seem to partition niche space at a bird feeder or series of feeders? a. Some birds eat the seeds at the perch of the feeder. Some more birds pick up the seeds at the feeder and fly away. Few more birds pick up the seeds fallen near the niche at the bottom of the feeder. In this way niche space (within, bottom and away the feeder) is partitioned at the bird feeder by the birds. 5) Behavior can be instinctive (genetically programmed) or learned. Birds at feeder exhibit both kinds. How could you determine whether a bird’s exploitation of a particular feeding niche is learned or instinctive? a. Instinctive or learned behavior for bird's exploitation of a particular feeding niche can be determined by performing a statistical test - "Chi-Square Test"

Chi-Square Contingency Table

Niche A Species 1 observed: 1

Niche B 6

Niche C 0

Row Totals 7

(expected): (2.47) Species 2 observed: 0

(2.26) 1

(2.26) 7

8

(expected): (2.82) Species 3 observed: 8

(2.59) 0

(2.59) 0

8

(expected): (2.82) Species 4 observed: 2

(2.59) 0

(2.59) 0

2

(expected): (0.71) Species 5 observed: 0

(0.65) 4

(0.65) 0

4

(expected): (1.41) Species 6 observed: 1

(1.29) 0

(1.29) 4

5

(expected): (1.76) Column totals: 12

(1.62) 11

(1.62) 11

Grand total:

(expected):

34

Chi-Square Calculation Table Cell Label

Observed

Expected

niche,

number (O)

number (E)

species A1 A2 A3 A4 A5 A6 B1 B2 B3 B4 B5 B6 C1 C2 C3 C4

1 0 8 2 0 1 6 1 0 0 4 0 0 7 0 0

2.47 2.82 2.82 0.71 1.41 1.76 2.26 2.59 2.59 0.65 1.29 1.62 2.26 2.59 2.59 0.65

(O-E)

-1.47 -2.82 5.18 1.29 -1.41 -.76 3.74 -1.59 -2.59 -0.65 2.71 -1.62 -2.26 4.41 -2.59 -0.65

(O-E)²

(O-E)²/E

2.1609 7.9524 26.8324 1.6641 1.9881 0.5776 13.9876 2.5281 6.7081 0.4225 7.3441 2.6244 5.1076 19.4481 6.7081 0.4225

0.87486 2.82 9.51504 2.3438 1.41 0.32818 6.1892 0.9761 2.59 0.65 5.6931 1.62 2.26 7.50892 2.59 0.65

C5 C6

0 4

1.29 1.62

-1.29 2.38

1.6641 5.6644

1.29 3.4965 52.8057...