Contemporary birds: why are they so tuneful and colorful?

1. Contemporary birds: why are they so tuneful and colorful? Moedifah Adams Department of Biodiversity and Conservation Biology University of the Western Cape 2218311@uwc.ac.za

2. Introduction : • This presentation is based on courting and color within various bird species and the reasons for why this is so.

3. birds are more coloured than any of the other vertebrates, they are capable of flying from there enemies and nest in ,inaccessible sites. There are three types of pigments found namely:Melanins, Carotenoids and Porphyrins. Adult coloration in many birds coincides with the advent of sexual maturity ,it suggests that sex hormones may play a part in plumage coloration. Castrated males don’t loss colour but the females do, the female hormone inhibits male coloration. In Phaloropes the nuptial plumageis more colourful in the females than males. Bright colours of the female depends on the male hormone testosterone. There is a wide variation within plumage colour due to sex, age, diet, disease , temperature, humidity, solar bleaching. Species that are either social or fairly sedentary both of these situation are conducive to interbreeding. Color in birds: P, Davis Kenrick P (2004)

4. Melanism is also established within isolated populations of species that is capable of replacing normal coloration , Erythrism in birds result due to ,too much excess of the red pigments. • Two chief varieties of the normal plumage dimorphism : sexual and seasonal , many species are monomorphic and show neither sexual or seasonal changed in plumage coloration. • Heredity plays a major role in controlling feather colour,heredity genes in feather germ that determine color are very stable. • Birds of different orders are also capable of exchanging colour. • Genetic mutations occur which affect not only the color but the structure of feathers as well. • Mutations can cause a complete loss to feathers.

5. Colour in birds are important for their behaviour effects , it has intrinsic value towards the birds. Pigmented feathers are the stronger and wear better than unprigmented feathers, radiant eat is absorbed by the pigments. Evolutionary development of colours can be divided into 2 namely: Cryptic and Phanetic colours. Cryptic coloration I birds are related to protection against predators, which is linked to a birds habitat surroundings. Birds who live on fine grained, dusty or sandy soil have a smooth and even coloration, birds that are coarse grains have a disruptive pattern of coloration. Distinctive coloration serves as a quick mark for distinguishing friend and foe and holding a flock together. Recognition marks have sexual significance, bright coloured males have sexual significance of sexual selection. Coloration is used for courtship ceremonies to attract mates, stimulate them into sex readiness. The uses of colour: htp

6. A majority of bird produce vocal sound of 1 or many, more than half of all birds are song birds. Birds vocalization are of two kinds : the call and the song, calls are brief sounds with relatively simple acoustic structure, no clear organization patterns. Calls coordinate the behavior of other species in nonsexual, maintenance behavior like: flocking, migration, feeding and actions towards predators. Song are used for the defense of territory and maintaining the pair bond between mates. Species show greater variations in song than others. Males do the singing and some females like the tropical female also sing. Songs , calls and other sounds:

7. Songs are judged by the time put into it by the birds, can be divided into 3namely: Reproduction, Social and individual, but I will only specialize in reproduction. Reproductive functions: Proclaim the sex of the individual, to produce another individual to reveal its sex. To indicate vigor and dominance , advertise for and allure a mate. Territory , stimulate and synchronize sex behaviour, strengthen the pair bond. Song is basically for both territory and sexual function, 2 different songs, 1 for territory and the other for courtship. In many species of birds the male always sings vigorously until a mate has been found, the song will either stop a one time or will become less frequently. The male always sings the same number of songs a day , the equability of song influences its reproductive behaviour. Some of the large species of birds eg. Hawks and crows, don’t have a courtship call they depend on their large size and there courtship flights to impress the opposite sex. The function of voice: Kenrick P, Davis P (2004)

8. Bird vocabularies: • Many kinds of birds are able to recognize not only the different calls characteristics of the species but also the calls of individual birds, birds that arrive always emit landing calls. • Members of a pair recognize each other personally and transmitted information directed at only partners even over a distance. • Birds have voice vocabularies which enable them to talk. • Two or more species flock together when they are not breeding because natural selection has placed a premium on there distinctiveness in contact and there courtship calls. • Song is more complex structurally and functions a little in territory defends and when advertising for a mate. • Calls are associated with general behavioural situations like social contacts ,group movements, finding food, enemy avoidance and parent and young relations.

9. Some bird species use the wings in defending territory, the flapping is shared among the birds within local populations. Many species certain feathers are modified for the sound production in the wings. Example, Woodcock outer wing feathers are narrowed and stiffened, when spread apart the springtime courtship flight,the air rushing between them causes them to vibrate with a high whistiling sound. Some birds may make nonvocal sounds with there beaks. Songs are differentiated due to the loudness 2 types 1° songs & 2 ° songs: 1° songs are related to daily business of making aliving & also plays apart with genes, they are courtship songs, territory defense song & other signal songs. 1° songs are very high during territory & courtship. 2° songs are weak whisper group & only occurs over a short distance, 2° songs is a characteristic of young males & adult females. The song repertory of a pair is different from another pair, a isolated female will answer her mate but not another pair. Nonvocal sounds:

10. Cycles in song: High latitude birds have a seasonal variation in songs which is correlated with breeding activities & hormone production. Fullest song occurs in spring when birds are busy with territory establishment & courtship. Umated sings lower & more abundant than males. If male losses his partner. He will start singling again. Hormones play a role in when the singing should start. Birds active in the day start singing at dawn, vigorous singing occurs & slow s down in the afternoon & stops at night. All the start of breeding singing occurs all day & than afterwards it only occurs during the day & night.

11. Large birds have low pitched voices, while small birds have a high pitched voices. Birds are capable of distinguishing between 200 discrete sounds in a second. Families and genera of birds commonly exhibit similar characteristics in calls and songs. The difference between species and individuals in bird songs are more likely to be matter of sequence and there pitch of notes,songs are differentiated on the basis of loudness . The nature of song:

12. Mating season for birds starts during spring, the warmth & light plays a part not only with plumage & sex organs, but with their behavior as well as sex organs, but with their behavior as well. Reproductive behavior is divided into namely. Territory establishment, courtship, mate selection pair bond establishment, copulation & nest building There is great diversity among the species in the occurrence, timing & the duration of breeding activities, some choose mates before they establish territory. Sexual maturity occurs at different ages, in different species, sexual maturity does not appear full blown at a given age, but develops by stages. Courtship & mating habits

13. Pair Formation: • Coming together of two birds for the procreation is move or less durable bond that usually result in monogamy. • The duration of pair bond varies greatly between species & between individuals. • Pair formation is facilitated through an exchange of visual & auditory signals between potential mates. • A mated pair may remain together for life, for several years, for one year. • Birds are commonly attached by territory or personal recognition for each. • Compatibility between the pairs is a prerequisite to successful reproduction.

14. Durability of pair bonds • Not many birds species mate for life or for several successive years. • Females who retain the same mate from the season before will have a greater breeding season.

15. Types of mating • Mating systems may be divided into 4 namely: Promiscuity, Polygyny, monogamy & polyandry. • Promiscuity denotes a lack of choosiness by sexual partners & is used to describe polygyny systems in which pairs are non existent. • Polygyny is when a male mates with more than two females. • Polyandry is the opposite for polygyny because in this case is female mates with more than 2 males. • Monogamy is when the young leave the nest shortly after hatching.

16. Meaning of courtship display: • A courtshing male commonly ceases his signing & sheds his colorful feathers as soon as the female begins to incubate the eggs. • It reveals the biological costs of advertising either to defend a territory of to win a mate, the mate does all the courting & female selects the male. • He may posture so to reveal his gaudiest nuptial plumage & spread his tail & erects his crest, parade, fly with dizzying acrobatics singing his most fetching song & even collects food for his mate. • Plumage or behavior may broadcast a male’s genetic quality & influence a female’s choice of a mate. • Courtship stimulates sexual redness not only in the bird being courted but also in the bird doing the courting.

17. The reciprocal stimulation may be the chief function of the mutual courtship ceremonies of many colonial birds, this stimulus commonly results in the increase of sex hormones & frequently intensity courtship display behavior. • Courtship behavior originates from copulation with the female & the agonistic tendency to attack or escape. • Courtship have originated from 7 major behavioral elements: sexual, aggressive, fearful, alert, nesting, parental & juvenile begging for food.

18. Both sexes of a species are externally similar in appearances, the male & female often take equal parts in courtship activities. Sexual dimorphism provides striking differences between the male & female especially in nuptial plumage. The male with his conspicuous coloration, undertakes the courtship activities. It is significant that in may species the colourful feathers and often other structures used in courtship coincide in their period appearance. A female commonly invests much more time and energy in reproduction. The driving force resulting in extremes of sexual dimorphism are male to male competition and the female choice, mouth cavities of many birds are strikingly coloured and are prominently displayed in courtship ceremonies. Sexual Dimorphism & courtship

19. Song is employed in lovemaking as well as war or even in territory defence, courtship can be judged in some species by the amount of time the male devotes to song before and after he secures his mate. Courtship song is controlled by hormonal and psychic conditions. Often the injection of male hormones in birds will bring on courtship song and behaviours. Lovemaking male serenades his would-be mate not only with calls and songs but also with other songs. Contacts is another form of courtship, this is common amongst birds that lack sexual dimorphism, such courtship involve kissing, caressing, entwining necks, and nibbling each others feathers. There is a high correlation between courtship movements and the particular structures that are the males showiest ornaments. The dramatic effects of courtship displays in nearly all birds are enhanced by strangeness and frequently by their suddenness. Varieties of courtship display.

20. Courtship display may also take the form of dance rituals. Courtship displays in numerous species are performed in groups. Many primitive tribes throughout the world perform dances clearly derived from those of courting or fighting birds. The female approaches a male and perhaps nibbles at his ruff or head feathers , coition ensues. Courtship dancing not only occurs on land but also in the sea water. Many birds conduct their courtship activities in the air. The courtship consists merely in a fight that exposes the more colourful markings of the male to the eyes of the female. Fighting between males is accepted courtship practice in many species. If another male waddles to interrupt this lovemaking the pair will copulate and will establish a pair bond.

22. Everyday activities will become formalised and adapted to functions. When courtship feeling occurs the ale will always feed the female. Food is passed from the male to the female in various ways. Most commonly the male places it in the female’s gaping mouth. Courtship feeding are stylised ceremonies of billing, fencing, gaping, and similar forms of lovemaking. Symbolic courtship rites.

23. Baptista L., Welty JC .(1990) The life of birds 4th ed. Harcourt Brace Jovanovich College publishers. United States of America. References