Egg shell morphology of an amblyceran louse, Hohorstiella rampurensis (Phthiraptera) infesting ring dove, Streptopelia decaocta

Scanning electron microscopy (SEM) study showed that miniature rice grain like egg shell of Hohorstiella rampurensis was covered by obliquely placed opercular disc. The apophyses were present only on one side of the egg shell. There were 25-35 long elongated rod like apophyses (apically turned), which were arranged in 3-4 rows and occurred in pair. The nature of egg shell of H. rampurensis characteristically differed from that of H. lata (the only species of Hohorstiella studied, so far). The study further indicates about the role of egg morphology as a guide to louse taxonomy.

In vitro biology of Columbicola bacillus (Phthiraptera: Ischnocera)

An ischnoceran louse, Columbicola bacillus infesting Ring dove, Streptopelia decaocto was subjected to in vitro experimentation. The data obtained through in vitro experimentation was utilized to construct the life table and to determine its intrinsic rate of natural increase (rm). The value of rm appeared to be 0.054. At this rate, the population of C. bacillus is supposed to be double after 12.95 days, indicating that it is moderate breeder.

Biomechanics and control of vocalization in a non-songbird

The neuromuscular control of vocalization in birds requires complicated and precisely coordinated motor control of the vocal organ (i.e. the syrinx), the respiratory system and upper vocal tract. The biomechanics of the syrinx is very complex and not well understood. In this paper, we aim to unravel the contribution of different control parameters in the coo of the ring dove ( Streptopelia risoria ) at the syrinx level. We designed and implemented a quantitative biomechanical syrinx model that is driven by physiological control parameters and includes a muscle model. Our simple nonlinear model reproduces the coo, including the inspiratory note, with remarkable accuracy and suggests that harmonic content of song can be controlled by the geometry and rest position of the syrinx. Furthermore, by systematically switching off the control parameters, we demonstrate how they affect amplitude and frequency modulations and generate new experimentally testable hypotheses. Our model suggests that independent control of amplitude and frequency seems not to be possible with the simple syringeal morphology of the ring dove. We speculate that songbirds evolved a syrinx design that uncouples the control of different sound parameters and allows for independent control. This evolutionary key innovation provides an additional explanation for the rapid diversification and speciation of the songbirds.