Cognitive Processing in Bird Song Development and Use

1. Cognitive Processing in Bird Song Development and Use Psych 1090 Lecture 11

2. Oscine birds learn their songs, just like human children learn their language….. Clearly, there are innate predispositions to learn both song and language and particular brain areas are involved in the processes for both birds and humans But learning does occur…..and usually involves some cognition

3. And, as we’ll see, it isn’t only what the bird learns that is important but also the way it chooses to use its vocalizations the choice of which song to sing or the way in which it is sung can have significant effects on other birds

4. But, with respect to acquisition, birds need to learn • what constitutes the communication code • which notes or songs to sing • what order in which to sing them • from whom to learn the code • from one’s father • from one’s neighbors • from a combination of tutors

5. And how to use the communication code • to recognize individuals • to attract mates • to defend territories And, it appears that all these behavior patterns involve, to some degree, some forms of cognitive processing

6. Specifically, the natural world is an extremely complicated place of myriad interactions-- some obvious, some hidden-- but all of critical importance if one is to understand its workings

7. Information must be processed, sorted, ignored or acted upon by all creatures And, as we’ve said before, fully programmed responses would be almost useless in dealing with a world of myriad situations Flexibility in processing in crucial for success

8. John Smith (1998) sums it up: “…an animal has become flexible when it can process individually acquired knowledge, seek further information and hold a range of options open as it works to anticipate the course of an event. Such an individual can fine-tune and modify its responses. It can evaluate unexpected information and cope better with variable environments than can the ‘releaser-driven’ individuals posited by early ethologists.”

9. We’ll start with acquisition and then go on to use But remember that these are going to be inter-related issues for some avian species

10. Looking at birds’ choice of from whom they will learn their songs…. doesn’t necessarily reflect cognitive any levels of processing… Many times birds just learn to sing from their fathers…

11. Simply because they hear their father’s song more frequently than any other song around… But then they do differentiate their song enough to allow themselves to be recognized individually So that they don’t sound like dad or their brothers

12. But in other cases, birds choose to learn from territorial neighbors particularly ones that appear most dominant in the area In such cases, cognitive processing is clear because they evaluate the various singers

13. But even then the issue isn’t entirely settled because there are factors involving whether the birds stay where they learned their song or disperse to another area with a different song tradition

14. And although “tradition” generally refers to a song dialect that is, a variation on the species-specific format it can also sometimes mean that the newcomer has to fit into dominance system in a given area

15. All birds do learn to something about song in their first year And some actually start to sing in that hatchling year Whereas most won’t actually come into full song until they are almost a year old…their next spring

16. In general, the pattern of song learning proceeds as was described by Marler and his colleagues in the 1960s:

17. The differences are in the details… Different species learn at somewhat different rates, different numbers of songs, and with more or less flexibility but the basic pattern is the same

18. Birds like indigo buntings put down song memories in their first year, but then migrate away and return to areas that are not necessarily those in which they were hatched they then switch their songs to replicate that of the most dominant male in the new area

19. Birds like chaffinches, however, try to sound different from their neighbors…. And appear to be able to learn songs in both their first and second years…. According to recent work, they sound like neighbors who are 3 or 4 territories away…. Given that actively learning songs at such a distance is unlikely,

20. What probably is happening is that birds sort each other out and choose to nest away from neighbors that sound like they do…. Now, given that some territories are better than others, one could begin to imagine the types of dominance games that must be played in such a situation!

21. Which, if nothing else, means that both species, in different ways, have to evaluate the interactions among at least some different males in the area The process involves the transitive inference work we’ll discuss next week and suggests at least some level of cognitive processing

22. We’ll talk more about such aspects in a bit… But you also need to know something about the flexibility in the song acquisition process that was not initially expected… Birds were once thought to have a critical period

23. and also a restrictive song template The idea was that the birds heard lots of song when they were first hatched because the adult birds in the area were still defending their territories from other birds

24. The idea of a template was to filter out all the allospecific songs so that they wouldn’t learn the ‘wrong’ song And the idea of a critical period was that they’d be sure to get song when dad was singing close to the nest, again insuring the ‘correct’ song

25. The template and critical period ideas came from studies done on white-crowned sparrows raised in social isolation and given tutor audiotapes so that researchers could control exactly what the birds heard and when they heard it

26. Under such conditions, white-crowned learned best between days 10 and 50 and ignored songs of other species that they heard on tape But, of course, the conditions did not replicate reality

27. It turns out that white-crowns are much more flexible when their tutors are live: If they hear only one tutor song to day 50, they sing that song….. But if they have social interactions with adult birds at least up to day 100, They will switch and sing more of the song they hear later

28. One can argue that what is occurring is simply an ‘overwriting’ of the earlier song by more recent material Or that learners are just ‘remembering’ song elements of the later tutors from some innate storage bin…. But those explanations are not entirely enough….

29. First, birds that do not hear any tutor sing a totally bizarre song, so they can’t just create songs from innately stored material That is, some memories have to be laid down before they can be recalled

30. Second, if white-crowned sparrows are put in situations with a bird that sings the original song it learned…. it will switch back to that song; that is, revert to the song it would seem to have forgotten….. and can actually switch back and forth between different songs depending on what it hears

31. Now, one might conclude that the bird is just reacting in a species-specific manner, replicating, tape-recorder like, what it has just heard…. But, given that white-crowned sparrows normally sing only a single song, such behavior is not likely to have been hard-wired in But rather the bird is processing what it has heard and reacting appropriately….

32. Other birds give clearer evidence of processing in terms of how they learn and sing their songs particularly when they have a very large repertoire large numbers of songs are both difficult to learn and difficult to maintain in a given order so as to retain immediate variety (not repeating what was just sung)

33. Some of the best studied birds in this regard are nightingales they learn strings of over 60 different songs and the sequence of songs in a their song bout actually represents a sequence of behavioral decisions after singing each song, the bird is making a decision about the next song in the sequence—

34. that is, the birds engages in some form of cognitive processing—and humans can abstract rules about these decisions Moreover, careful study has shown that the ordering of the songs is of biological importance to the singer and not just an artifact of the analysis done by a researcher

35. When singing, the nightingale actually chunks its repertoire into groups (or, as the researchers say, “packages”) of about 3-5 songs The birds maintain the serial order of the packages but not necessarily that of songs within each package So researchers see a pattern like the following in terms of learning and recall….

36. 1-5 6-9 Rendition #1 10-16 17 18 17-20 21-27 19 20 28-34 35-40 41-46 47-54 17 18 55-60 61-63 20 19 Rendition #2 64-70

37. Further studies show conclusively that storage and production process does not simply involve paired associations between song-types Otherwise, birds could not go from, for example, no. 19 in one packet to no. 22 in another packet at one time, and a different between-packet order at another time

38. Although Todt and Hultsch do not suggest that this intra-package ordering could be important in song-matching which we’ll see is a critical issue for other birds that we’ll discuss in this lecture the possibility exists

39. But how do the birds learn these long lists—particularly if they hear lots of birds singing around them? But what happens if you give a bird a long list—say, of 60 songs or several such lists in which songs closest to one another do not have any particular similarity…

40. And what if the songs were not separated in any special ways…. how would a nightingale form a repertoire of its usual 100 or 200 songs? To figure it out, you do a series of clever experiments like those of Todt and Hultsch

41. They began by exposing young nightingales to several different long series of songs in the laboratory, called master strings By permuting song orders in the different strings, the number of song repetitions, and other variable such as social interaction,

42. they determined what was needed for the birds to acquire the songs and how birds ordered these songs in their singing bouts Specifically, as would humans, the birds classified the large numbers of songs heard in master strings into smaller, more manageable chunks.

43. The size of these chunks or “packages” , of three to five songs, relates directly to the chunks seen in singing and is probably constrained by short-term memory

44. The songs in each package seem to be learned at about the same time and to arise early in the process of song development and, as in the final version, song order is quite variablewithin the packages

45. But even as the birds learn, the packages are themselves arranged in a stable order, and this order reflects the context, or the master string, from which the songs were learned This package ordering, however, in contrast to the structure of the packages themselves, emerges relatively late in the song development process

46. There are no limits to the number of packages that are strung together, and the number is determined by the length of the master string that the bird hears But that’s not all: often, late in development, a nightingale invents a new set of songs…

47. but the set derives from those already in a given package Interestingly, birds that hear the same master strings may have different package boundaries and thus somewhat different overall song order, maybe for individual identity

48. but the rigorous general form of the packages will be maintained that is, packages never vary from the 3-5 song limits Now, sometimes birds were given multiple master strings…

49. when such birds are practicing during the acquisition process, the intervals between imitations acquired from the same master string or context group were significantly shorter than the intervals between imitations acquired from different context groups.

50. That’s important, because it suggests how the birds store the strings…. That is, if the time needed to access the stored representation of song-types varies depending on whether retrieval is from within a given context group or from a different context group…