Feral Pigeon Project PDF

Preview

Summary

Download Feral Pigeon Project PDF

Description

STUDENT ID: 14096343

Feral Pigeon Project STUDENT ID: 14096343 Word count: 911

1

STUDENT ID: 14096343 INTRODUCTION Sexual selection in birds requires a communication between males and females. Whether it is the song, plumage colour, size, morphology, or social dominance that provides the information about the optimal mate choice, depends on the species (Cotton, et. al 2006; Ferrer, et. al 2002). If the signalling features are not the preferred ones by the opposite sex, this can result in members of the population possessing the lower quality features not being recognised (Price, 1998, p. 252) and therefore the chance to mate and produce offsprings decreases. It has been suggested that the selectivity of the individuals should be affected by their own quality (Burley, 1977), therefore the individuals of better quality should be more selective than the low quality individuals (Burley, 1977; Hawkins, 1918). During this experiment the plumage colour preferences were observed in mating feral pigeons to determine whether they mate in a random matter or whether they are selective and the discrimination and the choice of mate is based on the phenotype, thus the assortative mating is taking place (Galipaud, et. al 2012; Johnston, 1989; Bortolotti, et. al 2008). To determine whether a random or a non-random mating is taking place in feral pigeons, two hypothesis were tested: (1) Male pigeons select their female mates independently of their colour; (2) Female pigeons accept the courtship and select their mates independently of their colour.

MATERIALS AND METHODS Feral pigeons were observed throughout January and February 2016, at Canterbury train stations, Canterbury High Street and Rochester High Street. Data of male courtships, mating attempts and female acceptance were collected and the number of successful matings noted. However, due to an unfavourable weather conditions during the time of observation (cold, windy, rainy) not enough mating activity was observed. Instead, the data provided were used. The population (N = 111) was composed of both sexes and divided into three groups based on their colour - melanic (N = 35), wild type blue/grey (N = 54), and ‘others’ (N = 22) including all different colours of pigeons. Plumage types were noted and mating attempts of males were recorded. Female acceptance of the courtships were recorder. To examine how the mate choices were made the expected frequencies of plumages for mating pairs were generated if they mated in a random matter. These were compared to the observed frequencies. Non-random mating based on plumage colour was analysed using the Chi-square test of independence to determine whether there is an association between a mate choice and the plumage colour.

2

STUDENT ID: 14096343 RESULTS During the experiment period, the most frequently observed plumage colour (48.65%) was the Wild type blue/grey (WT). This phenotype is the most common amongst feral pigeons. WT males preferred WT females; melanic males preferred melanic females for courtship (Table 1). Mating attempts Melanic males WT males ‘Other’ males Total

Melanic females 16 12 8

WT females 14 13 10

‘Other’ females 11 9 4

Total courtships 41 34 22 97

Table 1: Behavioural and plumage displays were considered a male courtship towards female pigeons. Males seem to prefer females of the same colour as their own.

Females of different plumage categories showed higher selectivity when choosing their mate; they did not accept all attempts for mating (Table 2). Female acceptance Melanic females WT females ‘Other’ females Total

Melanic males 2 4 2

WT males 6 3 1

‘Other’ males 5 6 2

Total matings 13 13 5 31

Table 2: Not all male courtships were accepted by females. Only around 1/3 of mating attempts were successful.

Results of the Chi-square test show that male choice of mate is not dependent on the plumage colour of females (X2 = 5.018875, DF = 4, p > 0.25); the hypothesis (1) is not rejected, and therefore males choose their mates independently on the plumage colour. However, in female feral pigeons the results show that females are more selective with their mates than males (X 2 = 10.203821, DF = 4, p< 0.05); the hypothesis (2) is rejected.

DISCCUSION Assigning the plumage categories was straightforward as the two main groups (WT, melanic) are common amongst the population. However, the ‘other’ category contains all other colours, such as white, red, pied and grizzled, that did not fit in any other group. During this experiment, two types of mating pairs were observed: (a) pairs of identical plumages that mated homotypically (Johnson, et. al 1989); (b) pairs of unlike plumages mated heterotypically ( Johnson, et. al 1989). According to the

3

STUDENT ID: 14096343 results, most of the mating pairs were homotypical, thus it shows that pigeons mostly prefer individuals of the same colour as their own. This experiment suggest that females are relatively more selective than males when it comes to the plumage colour. This suggestion is supported by results of experiment done by Burley (1977), which agrees that females choose their mates based on colour. Females are more selective in their mate choice because they can obtain benefits when choosing the high quality male (Cooke, et. al 1985; Moller, 1997). Benefits acquired from the right choice can be a protection of a nesting site, more success at feeding stations, and better and more offsprings. This usually results in high quality females pairing with high quality males, and therefore low quality individuals are left to pair together. Although in this experiment males do not seem to choose their mates based on the colour that does not mean that they are not selective with their mates. There are many other different factors that might affect the mate choice (Johnson, et. al 1989), such as social dominance that is associated with fitness (Cotton, et. al 2006), body size, various behaviour of each individual, etc. However, completely different results were obtained by Warriner, Lemmon and Ray (Seiger, 1967). These suggest that the mate selection based on colour is dominant in males, not in females. Many experiments show that bird females are selective, however, many studies on feral pigeon are inconsistent, and some show no plumage preferences at all (Johnson, et. al 1989).

CONCLUSION From this experiment, it can be said that female feral pigeons are more selective than males. Plumage colour is one of the secondary sexual traits. However, it is not the only criterion by which the mate choice is made amongst pigeons (Burley, 1977). There are many other factors that affect the choice and need to be considered when observing the mating preferences of birds. To determine all these criteria and factors used when choosing mates, more research needs to be done.

4

STUDENT ID: 14096343

REFERENCE LIST 

Bortolotti, G. R., González, L. M., Margalida, A., Sánchez, R., Oria, J. (2008), ‘Positive assortative pairing by plumage colour in Spanish imperial eagles‘, Elsevier, 78, pp. 100-107.



Burley, N. (1977), ‘Parental Investment, Mate Choice, and Mate Quality’, PNAS USA, 74 (8), pp. 3476-3479.



Cooke, F., Findlay, C. S., Rockwell, R. F., Smith, J. A. (1985), ‘Life History Studies of the Lesser Snow Goose (Anser caerulescens caerulescens). III. The Selective Value of Plumage Polymorphism: Net Fecundity’, Evolution, 39 (1), pp. 165-177.



Cotton, S., Small, J., Pomiankowski, A. (2006), ‘Sexual Selection and Condition-Dependent Mate Preferences’, Elsevier - Current Biology, 16, pp. 755-765.



Ferrer, M., Penteriani, V. (2003), ‘A process of pair formation leading to assortative mating: passive age-assortative mating by habitat heterogeneity’, Elsevier - Animal Behaviour, 66, pp. 137-143.



Galipaud, M., Bollache, L., Dechaume-Moncharmont, F. X. (2012), ‘Assortative mating by size without a size-based preference: the female-sooner norm as a mate-guarding criterion’, Elsevier - Animal Behaviour, 85, pp. 35-41.



Hawkins, C. J. (1918), ‘Sexual Selection and Bird Song’, The Auk, 35 (4), pp. 421-437.



Johnston, R. F., Johnston, S. G. (1989), ‘Nonrandom Mating in Feral Pigeons’, The Condor, 91 (1), pp. 23-29.



Moller, A. P. (1997), ‘Immune Defence, Extra-Pair Paternity, and Sexual Selection in Birds’, Proceedings: Biological Sciences, 264 (1381), pp. 561-566.



Price, T. (1998), ‘Sexual Selection and Natural Selection in Bird Speciation’, Philosophical Transactions: Biological Siences, 353 (1366), pp. 251-260.



Seiger, M. B. (1967), ‘A computer Simulation Study of the Influence of Imprinting on Population Structure’, The American Naturalist, 101 (917), pp. 47-57.

5...