Animals that breed seasonally show a variety of behavioral patterns during the mating season, the study of which provides qualitative insights into the nature of breeding in the natural environment. The present study sought to test the influence of morphological and physiological traits on the reproductive attractiveness of Junco birds. Specifically, the effects of two variables at once were evaluated: the proportion of white plumage on the brown coloration of male birds and the concentration of 2-pentadecanone in the reproductive secretion of individuals. It can be seen that each of the variables was quantitative, and its expression was represented by either a fractional value or a percentage (Soetewey). It was assessed to what extent these variables could be related to the number of offspring among male birds.
The results obtained showed compliance with the initially set statement; namely, they confirmed the relationship between the analyzed variables. However, it is fair to say that while the direction of this correlation was expected, its strength was unexpected. Specifically, linear regression and correlation models were used to test the relationship between the proportion of white areas on male bird coloration. The results showed well that an increase in the number of white spots on the tail of Junco birds was associated with an increase in the number of offspring produced by this individual. However, the quality of this association was weak, with a Pearson correlation coefficient of only 0.19, implying that the number of white spots and reproductive attractiveness were weakly-moderately related (Fernando). For the concentration of 2-pentadecanone, the positive correlation power was almost three times higher. It follows from this that in contrast to the coloration of birds, female Juncos could pay attention to the smell of males in the mating season first of all because the secreted secretion possessing the odor of “attractiveness” contained an increased amount of the organic component.
The results obtained are in excellent agreement with the evidence previously published by other authors. For example, Whittaker et al. confirmed that the volatile compounds of Junco birds are reliable predictors of reproductive success in male birds (698). In another paper released six years later, Whittaker and colleagues observed that the metabolic activity of symbiotic bacteria inhabiting the odor glands of animals was responsible for this success (1). Interestingly, however, this evidence is not unique to birds. A paper by Zhou et al. showed that the volatile compounds of animals, particularly pandas, are critical for reproduction during the mating season (652). In other words, the evidence gathered in the present experiment reflects well the agenda relevant to the academic community.
It is not difficult to understand that the findings are of high applied value to conservationists and biologists. Indeed, the fact that a consistent relationship has been found between the physiological traits of male birds and their reproductive attractiveness signifies the specific effects of natural selection. It can be expected that, over time, the number of male birds whose glands produce small amounts of 2-pentadecanone during the mating season will slowly decline. For communities, this means that artificial use of this substance could be useful in helping populations with problematic dynamics. For example, if Junco bird populations — although, as it turns out, 2-pentadecanone for breeding is not unique to birds — are experiencing environmental pressure and are unable to reproduce, artificial scent application to males could correct the situation.
Another possible use of the findings is to prevent excessive breeding of birds that hurt the population. In particular, if specific individuals are found to have inherited genetic defects, but the amount of organic component in their scent is prohibitive, conservationists can isolate such animals from the environment to improve the situation in the population. This then has a long-lasting consequence, as the patterns found may potentially save entire natural ecosystems.
It is already clear that the results obtained fully cover the need to study at least the minimal basics of the behavioral patterns of Junco birds during the mating period. Previously, it might have been mistakenly thought that the bird’s appearance was the predominant characteristic, but the evidence of this work has demonstrated the opposite results. Internal effects were three times stronger than external impressions. The work adds to how pair association works during the mating season and shows one possible reason that determines a female’s choice of a particular pair.
Although this proves useful for conservation purposes, there is still a lack of accurate understanding of the causal constructs that determine the pattern found. It is clear that the secreted secretion has an arousing effect on the central nervous system of female birds, but the details of this effect are still part of future research. In addition, it is not known for sure whether 2-pentadecanone is the only volatile compound with such an effect. If not, it can be assumed that there are several substances secreted by symbiotic odorant gland bacteria which may have similar effects. In this case, however, it is expected that the substances have non-identical but similar effects since the metabolic activity of several molecules cannot be identical. Thus, research into the specific causes of the detected phenomenon has yet to be realized.
Works Cited
Fernando, Jason. “Correlation Coefficient.”Investopedia, 2021, Web.
Soetewey, Antoine. “Variable Types and Examples.”Stats and R. Web.
Whittaker, Danielle J., et al. “Experimental Evidence that Symbiotic Bacteria Produce Chemical Cues in a Songbird.” Journal of Experimental Biology, vol. 222, no. 20, 2019, pp. 1-12.
Whittaker, Danielle J., et al. “Bird Odour Predicts Reproductive Success.” Animal Behaviour, vol. 86, no. 4, 2013, pp. 697-703.
Zhou, Wenliang, et al. “Seasonal and Reproductive Variation in Chemical Constituents of Scent Signals in Wild Giant Pandas.” Science China Life Sciences, vol. 62, no. 5, 2019, pp. 648-660.