An investigation of syrinx morphometry and sound frequency association during the chirping period in lovebirds (Agapornis fischeri)

Abstract

Background: In the issue of biodiversity, the domestication of birds as pets and trade animals requires special attention as a conservation effort. Lovebirds (Agapornis fischeri) are popular birds worldwide, due to their varied ornamentation and melodic chirping sound. Syrinx structure is suspected to be the main source of sound production during the chirping period. This study aimed to investigate syrinx morphometry and its correlation with sound frequency produced in lovebirds. Methods: A total of 24 lovebirds of different ages and gender were investigated. Polymerase chain reaction method was performed to determine lovebird gender, meanwhile bird age was identified based on post-hatch recordings at the breeding farm. Thus, we enrolled male (n=12) and female (n=12) lovebirds aged 2 (n=4), 3 (n=4), and 4 (n=4) months in the investigation group, respectively. Fast Fourier Transform (FFT) was performed to evaluate sound frequency during chirping period. Then, syrinx morphometry was identified using a topographic approach and methylene blue staining. Each variable was evaluated with Image J software and vernier caliper. Results: Based on a topographical approach, we reported the general cartilage structure of the tracheosyringeal, bronchosyringeal, paired protrusions, tracheolateral muscles, sternotracheal muscles, and syringeal muscles in lovebird syrinx. In particular, the tympaniform membranes lateral lead a crucial role in modulating the frequency of male lovebirds more significantly (p=0,009) compared to female. On the other hand, the tympaniform membranes lateral dexter (p=0,02) and sinister (p=0,05) in females showed wider compared to male. We also reported a negative correlation between sound frequency compared to tympaniform membranes lateral dexter (y = -913,56x + 6770,8) and sinister (y = -706,16x + 5736). Conclusions: It can be concluded that the tympaniform membranes lateral produced the lovebirds’ primary sound. The sound frequency of male lovebirds was higher compared to female, however negatively correlated with the area of tympaniform membranes lateral.

Morphology of the syrinx of three species of birds from Brazilian cerrado (Psittacara leucophthalmus, Rhynchotus rufescens and Cariama cristata): Gross anatomy and light microscopy study

“…The superficial and deep syringeal muscles are examples of intrinsic muscles and, in this study, they were found only in the white‐eyed parakeet, similar to what was described for other parrots (Dewi et al, 2023; Gaunt & Gaunt, 1985). According to Casteleyn et al (2018), the most domestic bird species had no intrinsic syringeal muscles.…”

“…In this study, the pessulus was observed in red‐legged seriema and red‐winged tinamou. No pessulus is present in the white‐eyed parakeet, similarly to reported for other Psittacidae family birds such as monk parakeet and Patagonian parrot (Dyce et al, 2010; Gaunt & Gaunt, 1985) and loverbirds (Dewi et al, 2023). The composition of pessulus, dividing the airway within the syrinx, varies significantly in the avian species (Frank et al, 2006).…”

“…Probably, the absence of the medial tympaniform membrane in parrots does not harm them, as it seems that the lateral tympaniform membrane plays an important role in the production of sounds (Elemans et al, 2008). Moreover, Dewi et al (2023) cited only the lateral tympaniform membrane in the lovebirds that also belongs to the Psittacidae family. To these authors, the lateral tympaniform membrane produces the lovebirds's primary sound.…”

“…The syrinx is the organ that produces sounds in birds (Casteleyn et al, 2018; Dewi et al, 2023) and is located close to the tracheobronchial junction (Goller, 2022). It is of great importance for territorial marking, recognition of family members, socialization of the offspring in female birds and the luring of a mating partner in male birds (Casteleyn et al, 2018; Eens & Gorissen, 2005; Marler & Hamilton, 1966).…”

“…The morphology presented by the trachea and syrinx has already been described in several birds species, such as ostriches (Yildiz et al, 2003), Mallard duck (Frank et al, 2007), passerines and columbidae (Casteleyn et al, 2018; Ibrahim et al, 2020; Warner, 1972a, 1972b), long‐legged buzzard (Kabak et al, 2007), Japanese quail (Çevik‐Demirkan et al, 2007), greater rhea (Picasso & Carril, 2013), southern cassowary (Mclerney et al, 2019), domestic fowl (Casteleyn et al, 2018; Ibrahim et al, 2020; King, 1986) and in lovebirds (Dewi et al, 2023). However, to the best of our knowledge, there have been no previous studies describing the morphology of the trachea and syrinx in the red‐winged tinamou, white‐eyed parakeet and red‐legged seriema.…”