determining the dominant bird species among the northern ...tufted titmouse •is a medium-sized...

Determining the Dominant Bird Species among the Northern Cardinal, Dark-

eyed Junco, Tufted Titmouse, and the American Goldfinch in Lonaconing,

Maryland

Bird Communication

• Transmit information – Food

– Mates

– Attacks

– Escapes

– Territory

– Identifications

• Displays – Visual Displays

– Vocal Displays

Agonistic Behaviors

• Behaviors used when two birds interact – Hostile – Cooperative

• Threat Displays (TD) – Display wings and beak – Move towards – Attacks

• Submissive Displays (SD) – Turn head and beak away – Move away – Flee

Dominant Bird

• Use more TDs

• Assert status

• Move without hesitation to feeders or perch

• Rank higher

• Reserve access to mates, space, and food

• Take fewer risks

• Survive longer

Subordinate Birds

• Use more SDs

• Move tentatively

• Attacked by dominants

• Have less access food

• Displaced by dominant birds

• Move to new locations

• Have higher risk of death

Dominant Interactions

• Intraspecies Interactions

– Older dominate younger

– Males dominate females

– Larger dominate smaller

• Interspecies Interactions

– Larger dominate smaller

– More dominant depending on brain chemistry

Purpose of the Study

Look at the interactions between four different species of birds (Northern Cardinal, Dark-eyed Junco, Tufted Titmouse, and American Goldfinch) to determine which species is the most dominate in these interactions.

Northern Cardinal

• Is the largest bird – 42-48 g

– 21-23 cm

• Is sexually dimorphic – Males red

– Females brown with red tinges

• Eats seeds and fruit

• Flock with other cardinals in the winter

Dark-eyed Junco

• Is medium-sized – 18-30 g

– 14-16 cm

• Vary in color – gray to brown

– white underbelly

• Eat mainly seeds

• Flock with sparrows and bluebirds for protection

Tufted Titmouse

• Is a medium-sized bird – 18-26 g

– 14-16 cm

• Is a soft silvery gray color

• Eats seeds, nuts, and berries

• Flock with chickadees, nuthatches, kinglets, and woodpeckers

• Is assertive to smaller birds

American Goldfinch

• Is the smallest bird

– 11-20 g

– 11-13 cm

• Is sexually dimorphic only in summer

• Eats mostly seeds

• Flock with pine siskins and common red polls

Rationale

• Analyze video footage

• Examine interactions among the four species

• Use TDs and SDs to calculate an average Bird Threat Score (BTS) for each species

• Determine which species is dominant

Null Hypothesis

There will be no difference in the average bird threat score among the four bird species.

Alternate Hypothesis

There will be a difference in the average bird threat score among the four bird species.

Study Site

• January 21, 2014

• Lonaconing, Maryland

• Dan’s Mountain

• Snowfall- 12.7cm

• Temperatures- from -10 to 2.7°C

Study Site

• Project FeederWatch site – 2013 counts

– 11 winter feeder species

• Multiple feeders – Platform feeders with black-oil

sunflower

– Tube feeder with Nyjer seed

– Tube feeders with black-oil sunflower

– Suet feeders

Our Feeder and Seed

• Platform feeder

– Easy for birds to access

– Attracts large variety of bird species

• Black-oil sunflower seeds

– Has thin shell and easy to eat

– High in fat

– Favored by most bird species

Study Subjects

• Four bird species

– Northern Cardinal (NOCA)

– Dark-eye Junco (DAJU)

– Tufted Titmouse (TUTI)

– American Goldfinch (AMGO)

Interspecies Interactions

1. NOCA x DAJU

2. NOCA x TUTI

3. NOCA x AMGO

4. DAJU x TUTI

5. DAJU x AMGO

6. TUTI x AMGO

X

X

X

X

X

X

Video Footage

• 63 minutes

• Uploaded on YouTube

• Divided into groups

• Divided footage into 12.5 minute increments

Examining Agonistic Behaviors

• Threat Displays (TD)

– Attacking (AT)

– Moving Towards (MT)

• Submissive Displays (SD)

– Moving Away (MA)

– Fleeing (FL)

• No reaction (NR)

Bird Threat Scores (BTS)

• Record presence or absence agonistic behaviors

• Look at both birds in an interaction

• Threat Displays- – AT = 1

– MT=1

• Submissive Displays- – MA= 0

– FL=0

• No Reaction = 0

Calculating BTS

• Minimum score= 0 – No presence of TD

– Presence of SD and/or NR

• Maximum score= 2 – Presence of both TD (AT & MT)

– SD may be present

• Score =1 – MT is displayed

– SD may be present

BTS Example

Bird 1 Bird 2

MT = 1 MA= 0

AT= 1 FL= 0

BTS = 2 BTS=0

Calculating an Average BTS

Sum of all the Bird Threat Scores

for one species

number of interactions that

species was included

Average BTS Example

Bird 1 BTS

2

1

1

2

0

1

2

• Sample size 7

• Sum of BTS = 9

• Average BTS= 1.3

Calculating Interaction Scores

• Interaction Score = BTS Bird 1 + BTS Bird 2

• Maximum score= 4

– Both birds showed both TDs

• Minimum score= 0

– Both bird showed SDs or NR

Interaction Score Example

Bird 1 Bird 2

MT = 1 MT= 1

AT= 1 MA= 0

FL= 0

BTS = 2 BTS=1

Interaction Score = 3

Calculating the Average Interaction Scores

Sum of the Interaction Scores for one type of Interspecies Interaction

The number of interactions for that type of Interspecies Interaction

Total Interaction of a Species

• DAJU had the most interactions

• NOCA had the least interactions

0

10

20

30

40

50

60

NOCA DAJU TUTI AMGO

Nu

mb

er

of

Inte

ract

ion

s

Bird Species

Total Number of Interactions for Each Bird Species

Average BTS for a Species

0.10

0.48

0.63

0.32

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

NOCA DAJU TUTI AMGO

Ave

rage

BTS

Bird Species

Average Bird Threat Scores for the Bird Species • TUTI had the highest

average BTS

• NOCA had the lowest average BTS

• NOCA average BTS is different from DAJU and TUTI

0

0.5

1

1.5

2

2.5

3

3.5

NOCAx DAJU

NOCA xTUTI

NOCA xAMGO

DAJU xTUTI

DAJU xAMGO

TUTI xAMGO

Ave

rage

Inte

ract

ion

Sco

re

Bird Species Interactions

Average Interaction Scores for Bird Species Interactions

Average Interaction Scores

• DAJU x TUTI average was higher than NOCA x DAJU

• TUTI x AMGO had the highest average

Paired BTS

• NOCA the only interactions to have 0 scores

• All species had overlapping CI’s

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Ave

rage

BTS

Bird Species Interactions

Average BTS for Each Bird in Each Interaction Type

Species 1

Species 2

Hypotheses Revisited

• Null- There will be no difference in the average bird threat score among the four bird species.

Rejected

• Alternate- There will be a difference in the average bird threat score among the four bird species.

Accepted

Alternate Hypothesis Accepted

• NOCA average is lower than DAJU and TUTI

– 95% CI do not overlap

• AMGO average was not different

– Large 95% CI

• Dominant bird not determined

Problems with our Sample Size

12

4 5

29

13

7

0

5

10

15

20

25

30

35

NOCA xDAJU

NOCA xTUTI

NOCA xAMGO

DAJU xTUTI

DAJU xAMGO

TUTI xAMGO

Nu

mb

er

of

Inte

ract

ion

s

Bird Species Interactions

Total Bird Species Interactions • Sample sizes were low

• Confidence Intervals large

• NOCA interactions had low sample sizes

• DAJU interactions had larger sample sizes

Improving Our Study

• More data needed to reduce CI size – Longer videos

– More days of video

– More feeders with video

– More sites with feeders and video

– More populated sites

• More research and experience identifying different bird behaviors

• More practice identifying bird species

Problems with Zero BTS

00.20.40.60.8

11.21.41.61.8

Ave

rage

BTS

Bird Species Interactions

Avgerage BTS for Each Bird in Each Interaction Type

Species 1Species 2

• Zero scores

– No Reaction (NR)

– Submissive Displays (SD)

• Could zero scores indicate dominance?

Possible Cardinal Dominance

• Do other species already know the cardinal is dominant? – Once a species is considered dominant, the

number of challenges may be lower from other species (5)

• Do cardinals naturally avoid other species? – Only flocks with other cardinals (1)

• Do female cardinals behave differently? – No males viewed at our site

Additional Questions

• How do birds learn who is dominant and when do they cease to challenge dominant species?

• What makes a bird species dominant? – Is brain chemistry impacting the way these four

species behave?

– Do age or gender play any role in interspecies interactions?

– Do species behave differently depending on food source?