Bioology 460/560 Ornithology
Dr. David Swanson, Office: CL 180
** BEHAVIOR **
Behavior = an internally directed system of adaptive activities that ensure survival and reproduction.
- Experience and Inheritance (genetic factors) affect all behavior, so the innate vs. learned behavior controversy is somewhat artificial.
- Behaviors range along a continuum from those modified slightly by experience to those derived entirely from experience.
I. INNATE BEHAVIOR (Instinct) = behaviors appearing spontaneously (inherited via genetic information) serving to perform certain specific functions (e.g., Gull chicks peck at red spot on parent's bill to get food, chicks will also peck at artificial bills or even sticks with red spots - SEE HANDOUT).
* Example: Mobbing Behavior
II. LEARNED BEHAVIOR = adaptive modification of behavior by experience. Genetic constraints may limit what can be learned (e.g., Greenfinch can learn parts of Canary song, but sings them with a Greenfinch rhythm).
TYPES OF LEARNED BEHAVIOR
1) Imprinting = learning that occurs only during a restricted time period called the critical learning period. Once learned, it is not forgotten (e.g., ducklings will imprint most strongly on moving (and calling) objects when 13 -16 hrs old - establishes concept of parents and species-recognition.
- Imprinting also is involved in such things as adult habitat preferences, selection of nest sites and materials, etc.
2) Habituation = learning not to respond to meaningless stimuli (e.g., birds nesting near highways learn not to respond to traffic noise).
3) Conditioned Behavior = involves attaching a pre-existing response to a new or substitute stimulus (e.g., Pavlov's Dog). Important in modifying Fixed Action Patterns to fit environmental circumstances more precisely.
4) Trial and Error Learning = involves modifying response to stimuli or creating new responses (e.g., learning palatable and unpalatable foods). (SEE OVERHEAD).
5) Insight Learning = production of a new response upon reorganization of experience (commonly referred to as insight or understanding). A good example is tool using in birds. SEE PAGE 164, GILL.
SUMMARY: Much of bird behavior is innate, consisting of fixed action patterns, but fixed action patterns can be modified by conditioned learning to better match environmental conditions. Birds are also capable of "higher" learning to a greater extent than previously thought.
** BIRD VOCALIZATIONS **
- A few birds lack a syrinx and therefore have no voice, but are only capable of croaks and grunts produced by air passing through the respiratory tract (storks, vultures, some pelicans, Mute Swan).
- Most birds produce the voice with the specialized avian vocal organ, the syrinx.
- Vocalizations are one important means of communication in birds. Visual displays are the other major method. Communication = the actions of one animal convey information that influences the actions of other animals.
- Vocalizations in birds are of two major types:
1) Songs = relatively long and complex vocal displays with specific repeated patterns. Purpose = territory maintenance, pair bonding, and reproductive isolation between species (e.g., Willow and Alder Flycatchers).
2) Calls = short simple vocalizations. Purpose = enemy avoidance (distress and warning calls), flight calls, flock/contact calls, parent-young relations (feeding, nest).
LOCALITY INFORMATION IN BIRD VOCALIZATIONS - the physical structure of the sound produced influences the ability with which a listener can determine its source.
1) Short notes with a broad frequency range. A higher number of frequencies increases information about direction and distance. This type of call is good for contact calls or mobbing calls.
2) Faint, high-pitched, narrow frequency range, and long duration. This type of sound conceals the exact location of the sound-producer, but conveys information to conspecifics in the general area. This type of call is good for alarm or warning calls.
3) Low frequency sounds travel furthest - used for long-distance communication (e.g., owls, grouse booming, etc.).
Species Recognition = accomplished by acoustical structure of song and sometimes syntax (repetition of syllables, etc.); studies on aggressive response in male birds have revealed this information. Whether or not the same information is true for females is not certain.
Individual Recognition = accomplished via details of pitch, phrase structure, syntax, and composition of calls and/or songs. Important for pair-bonding and identification of young, parents, mates, etc., especially in colonial nesting species like many seabirds.
Repertoire = the number of different types of song that an individual is capable of singing. Varies from 1-2 in some birds to hundreds in other species (examples of the latter condition include wrens, thrashers, and mockingbirds).
- Large repertoires may increase male reproductive success (e.g., Great Tits with large repertoires sired heavier young than those with smaller repertoires). Resulted from: (1) large repertoires stimulated the female to a greater extent than smaller repertoires, or (2) males with a large repertoire acquired and maintained better territories than males with smaller repertoires.
Mimicry = imitating calls or songs of other species. The best mimics in North America are Northern Mockingbirds and European Starlings.
What is the purpose of mimicry? - The precise function is not known. It has been suggested that it may be involved in excluding competing species from the mimics territory, or it may assist in calling in other species to mob predators.