2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
Carolina gait (Poecile carolinensis)
American ornithologists have found that representatives of two species of titmice (black-capped and Caroline tit) can use olfactory signals to attract partners. To do this, they caught several individuals of both species in the zone of increased possible hybridization. It turned out that males and females prefer the smell of the secrets of individuals of the opposite sex of their species. An article describing the study was published in the journal Ecology & Evolution.
In the places where the habitats of two adjacent species intersect, the process of hybridization can occur, that is, the offspring of a hybrid of a new species can be obtained. Most often, this is not the most effective strategy for breeding, which is why representatives of a species are evolutionarily predisposed to choose partners from their own species. Various reproductive signals, which are manifested in both appearance and behavior, help in this. They help not only to attract individuals for mating, but also effectively drive away representatives of other species.
Among birds, the most common strategies for attracting mates are considered to be plumage color (in males it is usually much brighter than in females) and singing (moreover, as recent studies have shown, most often one species uses either one or the other strategy). It is also known that birds can use the smell of their own secrets to attract partners for further mating.
Olfactory signals are used by many species as a possible obstacle to hybridization (for example, it is found in insects and mammals), but such a strategy has remained poorly understood among birds. Alex Van Hyunh and Amber Rice from Lehigh University decided to fix this. They focused on two species of titmice, Poecile atricapillus and Poecile carolinensis, native to North America and covering one common hybrid zone from New Jersey to Kansas.
Scientists captured several individuals (both females and males) of both species and extracted samples of their secretions from the coccygeal glands. The presence of various substances in the secrets was assessed using gas chromatography-mass spectrometry, a method that combines gas chromatography and mass spectrometry. The analysis showed that the composition of secrets significantly differs from each other depending on the type of bird, the sex of the individual, and the date of collection: in particular, for example, the ratio of esters to other components (without ether) significantly (p = 0, 001) depends on the species.
Further, for a separate behavioral test, scientists captured 20 males and 9 females of black-capped tit, as well as 20 males and 10 females of Caroline. Scientists built an experimental setup in the form of a Y-shaped labyrinth: in each of the arms there were samples of the secretion of birds of the opposite sex, and in one - the same species, and in the other - another. Analysis of the behavior of birds in the maze showed that both males and females were more attracted by the secret of their species, and not another.
Time spent by males of different species with the secretion of females of different species
Time spent by females of different species with the secretion of males of different species
The authors of the work concluded that olfactory signals among titmice may be an important aspect that ensures not only the absence of hybridization in areas of increased opportunity, but also generally affects their reproductive success. At the same time, such a strategy - using a secret to attract individuals for mating - is rarely studied among titmice: scientists, nevertheless, hope that more attention will be paid to it in the future.
The reproductive success of birds can also be influenced by individual behavior patterns. Last year, for example, bird watchers showed that it is easier for courageous male tits to choose a female and form a mate with her, while shy individuals spend much more time on this.