Mockingbird Morphing Music: Structured Transitions in a Complex Bird Song

The song of the northern mockingbird, Mimus polyglottos, is notable for its extensive length and inclusion of numerous imitations of several common North American bird species. Because of its complexity, it is not widely studied by birdsong scientists. When they do study it, the specific imitations are often noted, and the total number of varying phrases. What is rarely noted is the systematic way the bird changes from one syllable to the next, often with a subtle transition where one sound is gradually transformed into a related sound, revealing an audible and specific compositional mode. It resembles a common strategy in human composing, which can be described as variation of a theme. In this paper, we present our initial attempts to describe the specific compositional rules behind the mockingbird song, focusing on the way the bird transitions from one syllable type to the next. We find that more often than chance, syllables before and after the transition are spectrally related, i.e., transitions are gradual, which we describe as morphing. In our paper, we categorize four common modes of morphing: timbre change, pitch change, squeeze (shortening in time), and stretch (lengthening in time). This is the first time such transition rules in any complex birdsong have been specifically articulated.

Composition and Potential Function of Fecal Bacterial Microbiota from Six Bird Species

Gut microbial communities play a fundamental role in health and disease, but little is known about the gut microbiota of pet bird species. This is important to better understand the impact of microbes on birds’ health but may also be relevant in a context of zoonoses. Total genomic DNA samples from pooled fecal samples from 30 flocks (4–7 pet birds per flock) representing over 150 birds of six different species (two Passeriformes: Northern Mockingbird (Mimus polyglottos) and Zebra Finch (Taeniopygia guttata), and four Psittaciformes: Lovebird (Agapornis, different species), Cockatiel (Nymphicus hollandicus), Red-rumped Parrot (Psephotus haematonotus), and Rose-ringed Parakeet (Psittacula krameri) were used for 16S rRNA gene analysis. Several taxa were found to be different among the bird species (e.g., lowest median of Lactobacillus: 2.2% in Cockatiels; highest median of Lactobacillus: 79.4% in Lovebirds). Despite marked differences among individual pooled samples, each bird species harbored a unique fecal bacterial composition, based on the analysis of UniFrac distances. A predictive approach of metagenomic function and organism-level microbiome phenotypes revealed several differences among the bird species (e.g., a higher proportion of proteobacteria with the potential to form biofilms in samples from Northern Mockingbirds). The results provide a useful catalog of fecal microbes from pet birds and encourage more research on this unexplored topic.

A Mockingbird Mimus polyglottos (Linnaeus, 1758) found in a stomach of a blue shark Prionace glauca (Linnaeus, 1758)

Un cenzontle Mimus polyglottos (Linnaeus, 1758) encontrado en el estómago de un tiburón azul Prionace glauca (Linnaeus, 1758) Un cenzontle Mimus polyglottos fue encontrado en el estómago de un tiburón azul juvenil Prionace glauca capturado cerca de la costa de Bahía Magdalena, Baja California Sur, México. Este pájaro continental es un elemento raro como presa de un tiburón. Esta nota contribuye a enfatizar el papel de Prionace glauca como un depredador oportunista y/o carroñero.