Effects of mycoplasmal conjunctivitis on the behavior

of house finches

Erin Hotchkiss,

Sonia Altizer, Andy Davis, John Cherry

Dept. of Environmental Studies,

Emory University

Fall 2003

House FinchCarpodacus mexicanus

• Native to southwestern North America

• Few individuals were released in New York in 1940 and spread rapidly

• Social flocks during fall and winter, feeder birds

• Human-altered habitats

Altizer

Mycoplasmal conjunctivitis

• Caused by the bacterium Mycoplasma gallisepticum

• Found in domestic poultry

• First sighted in winter of 1993-94

• Novel strain infects House Finches

• Easily recognizable symptoms

• Has been known to infect other birds

Altizer

(Years 1 – 3 following initial case reports)

Disease spread rapidly through eastern North America

Altizer

House Finch abundance declined after arrival of mycoplasmal conjunctivitis

Bird

s/H

our

1970 1980 1990 2000

01

23

Eastern VA, Eastern MD, DE

Year

Bird

s/H

our

1970 1980 1990 2000

02

46

810

Central PA, Eastern NY

Altizer

Biology of the host and pathogenCollaborative approaches

• Do epidemic patterns differ among regions?

• What triggers fall/winter epidemics?

• How do processes operating at the level of individual birds affect population-level processes?

• Is host movement, reproduction, or social behavior important to disease spread?

Altizer

Behavioral Studies

1. Does infection status correlate with feeding efficiency and duration?

2. Is aggression or displacement related to infection status?

3. How many feeder ports are contaminated and later visited by house finches and other species?

Study Design• Digital videotapes of feeder activity

• 4 – 14 October 2002

• At least 50 individuals were observed

• Behavior Tracker used to record feeding events

•Score, sex, band, social interactions, feeding (pecks and seeds), flock sizes, duration of feeding bout, number of ports visited, reason for leaving

1048 3314N =

INF

10

95

% C

I F

ME

AN

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

SEX

F

M

Effects of Infection on Flock Size and Feeding Duration

0

50

100

150

200

250

300

0 1 2

Infection Score

Ave

rag

e T

ime

at F

eed

er (

sec)

• Infected birds had longer feeding bouts• Uninfected birds fed in larger mean flock sizes compared to infected

Infection Status and Feeding

• Efficiency (seeds/pecks) was much higher for healthy birds

• Rate (seeds/sec) was also much higher for uninfected house finches

• The total number of pecks per bout increased with infection

• Total number of seeds eaten in a bout increased with infection as well (NS)

212157N =

SCORE

210

95

% C

I E

FF

.8

.7

.6

.5

.4

.3

.2

212157N =

SCORE

210

95

% C

I R

AT

ES

EC

.14

.12

.10

.08

.06

.04

Aggression

• Mostly infected females displacing healthy males

• No instances of healthy finches displacing infected finches

• G test and X2 test with p > x2.005 (d.f.=3)

0 10 5 01 17 3

Displaced

Dis

plac

ers

Port Contamination

Average number of ports visited per feeding bout for finches with a score of “2” was slightly higher than “0” and “1” finches

0

0.5

1

1.5

2

2.5

0 1

Infection Status

Av

era

ge

Nu

mb

er

of

Po

rts

Vis

ite

d

pe

r F

ee

din

g B

ou

t

More data needed

Implications

• Survival of birds infected with MG– Less efficient feeders and lower rates

– Time wasted on social interaction

– Smaller flock size

– Longer duration at feeders

• Uninfected house finches (and other bird species)– Displacement by infected birds

– Contamination of feeders

Future Studies

• Compare vigilance of infected and healthy finches

• The importance of seed handling time• Video data that is time-stamped for transmission study• Interactions with other bird species (especially those more vulnerable to MG)• Calculations of nutrition and energy expenditure

Acknowledgments

Thanks to Sonia and Andy for all of their ideas, help, and support

Thanks also to John Cherry for letting me take and add on to his house finch video data