Winona State University

BIOL 406/506 - ORNITHOLOGY

Lab Exercise

TERRITORY DEFENSE

AND ENERGY CONSERVATION



OBJECTIVE



Many birds establish and defend territories during the breeding season. These territories usually contain a variety of resources needed by the birds to successfully rear their offspring. Because some of these resources may be relatively scarce and consequently valuable, birds may attempt to protect them from other birds by defending the area in which they are located.



Defending a territory and its resources may require significant expenditures of energy on the part of the owner. Territorial birds should attempt to defend their territories by the most energy-conserving means possible. This exercise will examine the frequencies with which birds use various methods, differing in energy expenditure, to defend their territories.




HYPOTHESIS



Birds will use energy-conserving methods to defend their territories far more frequently than energy-demanding methods.

METHODOLOGY



The bird community in a Winona area habitat will be surveyed during a single morning to assess the frequency of use of various territory defense behaviors. All birds exhibiting one of four different territory defense behaviors will be counted regardless of species. The following behaviors will be recorded:

Song – Adult male bird singing on its territory (most energy efficient)

Posture/Approach – Threatening posture or movement by a territorial bird directed toward another bird

Pursuit – Territorial bird chasing (ground or aerial) another bird

Combat – Territorial bird engaging in physical attack of another bird (most energy expensive)

ANALYSIS



After data are collected, display the results in graphical form (percentage of total observations attributable to each of the four behaviors). Include a table listing all species (common and scientific names) observed exhibiting some type of territorial behavior. Compare the total frequencies of the various behaviors with the aid of a Chi-square test (Ecology lab manual), assuming (based on a null hypothesis) that all behaviors should be exhibited with equal frequencies.  In addition, use a paired t-test to compare the number of singing birds (energy-conserving behavior) to the sum of all other territorial behaviors (Posture + Pursuit + Combat) exhibited by birds (energy-demanding behaviors) across all observer groups.

EQUIPMENT



Binoculars

Data sheet


Ecology lab manual



_______________________________________________

Neal D. Mundahl


Department of Biology


Winona State University


Winona, Minnesota



Return to Ornithology Synopsis