Tempo and Pattern of Avian Brain Size Evolution.

Relative brain sizes in birds can rival those of primates, but large-scale patterns and drivers of avian brain evolution remain elusive. Here, we explore the evolution of the fundamental brain-body scaling relationship across the origin and evolution of birds. Using a comprehensive dataset sampling> 2,000 modern birds, fossil birds, and theropod dinosaurs, we infer patterns of brain-body co-variation in deep time.

Topographic Organization of Inferior Olive Projections to the Zebrin II Stripes in the Pigeon Cerebellar Uvula.

This study was aimed at mapping the organization of the projections from the inferior olive (IO) to the ventral uvula in pigeons. The uvula is part of the vestibulocerebellum (VbC), which is involved in the processing of optic flow resulting from self-motion. As in other areas of the cerebellum, the uvula is organized into sagittal zones, which is apparent with respect to afferent inputs, the projection patterns of Purkinje cell (PC) efferents, the response properties of PCs and the expression of molecular markers such as zebrin II (ZII).

Inferior olivary projection to the zebrin II stripes in lobule IXcd of the pigeon flocculus: A retrograde tracing study.

Zebrin II (ZII; a.k.a.

Is Cerebellar Architecture Shaped by Sensory Ecology in the New Zealand Kiwi (Apteryx mantelli).

Among some mammals and birds, the cerebellar architecture appears to be adapted to the animal's ecological niche, particularly their sensory ecology and behavior. This relationship is, however, not well understood. To explore this, we examined the expression of zebrin II (ZII) in the cerebellum of the kiwi (Apteryx mantelli), a fully nocturnal bird with auditory, tactile, and olfactory specializations and a reduced visual system.

Retinal anatomy of the New Zealand kiwi: structural traits consistent with their nocturnal behavior.

Kiwi (Apteryx spp.) have a visual system unlike that of other nocturnal birds, and have specializations to their auditory, olfactory, and tactile systems. Eye size, binocular visual fields and visual brain centers in kiwi are proportionally the smallest yet recorded among birds.

The anatomy of the bill tip of kiwi and associated somatosensory regions of the brain: comparisons with shorebirds.

Three families of probe-foraging birds, Scolopacidae (sandpipers and snipes), Apterygidae (kiwi), and Threskiornithidae (ibises, including spoonbills) have independently evolved long, narrow bills containing clusters of vibration-sensitive mechanoreceptors (Herbst corpuscles) within pits in the bill-tip. These 'bill-tip organs' allow birds to detect buried or submerged prey via substrate-borne vibrations and/or interstitial pressure gradients. Shorebirds, kiwi and ibises are only distantly related, with the phylogenetic divide between kiwi and the other two taxa being particularly deep.

A quantitative morphological analysis of the inner ear of galliform birds.

The function of the inner ear is dependent on its physical structure and there is therefore a strong correspondence between inner ear morphology and hearing capabilities. In this study, we examine the morphology of the inner ear and use this relationship to predict the hearing range and sensitivities of species within the Order Galliformes (chicken, quail and allies). All galliforms share a similar inner ear morphology, which is characterized by gradients in hair cell morphology that are similar to other birds.

Brain size and morphology of the brood-parasitic and cerophagous honeyguides (Aves: Piciformes).

Honeyguides (Indicatoridae, Piciformes) are unique among birds in several respects. All subsist primarily on wax, are obligatory brood parasites and one species engages in 'guiding' behavior in which it leads human honey hunters to bees' nests. This unique life history has likely shaped the evolution of their brain size and morphology.

Ecomorphology of eye shape and retinal topography in waterfowl (Aves: Anseriformes: Anatidae) with different foraging modes.

Despite the large body of literature on ecomorphological adaptations to foraging in waterfowl, little attention has been paid to their sensory systems, especially vision. Here, we compare eye shape and retinal topography across 12 species representing 4 different foraging modes. Eye shape was significantly different among foraging modes, with diving and pursuit-diving species having relatively smaller corneal diameters compared to non-diving species.

Aromatase expression in the brain of the ruffed grouse (Bonasa umbellus) and comparisons with other galliform birds (Aves, Galliformes).

The enzyme aromatase is important for regulating sexual and aggressive behaviors during the reproductive season, including many aspects of courtship. In birds, aromatase is expressed at high levels in a number of different brain regions. Although this expression does vary among species, the extent to which the distribution of aromatase positive cells reflects species differences in courtship and other behaviors is not well established.

Discovery of a lipid synthesising organ in the auditory system of an insect.

Weta possess typical Ensifera ears. Each ear comprises three functional parts: two equally sized tympanal membranes, an underlying system of modified tracheal chambers, and the auditory sensory organ, the crista acustica. This organ sits within an enclosed fluid-filled channel-previously presumed to be hemolymph.

Morphometric analysis of telencephalic structure in a variety of neognath and paleognath bird species reveals regional differences associated with specific behavioral traits.

Birds exhibit a huge array of behavior, ecology and physiology, and occupy nearly every environment on earth, ranging from the desert outback of Australia to the tropical rain forests of Panama. Some birds have adopted a fully nocturnal lifestyle, such as the barn owl and kiwi, while others, such as the albatross, spend nearly their entire life flying over the ocean. Each species has evolved unique adaptations over millions of years to function in their respective niche.

Interspecifc variation in eye shape and retinal topography in seven species of galliform bird (Aves: Galliformes: Phasianidae).

Eye morphology and the retinal topography of animals that live in either 'open' (e.g., grassland) or 'enclosed' (e.

Inner-ear morphology of the New Zealand kiwi (Apteryx mantelli) suggests high-frequency specialization.

The sensory systems of the New Zealand kiwi appear to be uniquely adapted to occupy a nocturnal ground-dwelling niche. In addition to well-developed tactile and olfactory systems, the auditory system shows specializations of the ear, which are maintained along the central nervous system. Here, we provide a detailed description of the auditory nerve, hair cells, and stereovillar bundle orientation of the hair cells in the North Island brown kiwi.

Evidence for an auditory fovea in the New Zealand kiwi (Apteryx mantelli).

Kiwi are rare and strictly protected birds of iconic status in New Zealand. Yet, perhaps due to their unusual, nocturnal lifestyle, surprisingly little is known about their behaviour or physiology. In the present study, we exploited known correlations between morphology and physiology in the avian inner ear and brainstem to predict the frequency range of best hearing in the North Island brown kiwi.

Anatomical specializations for nocturnality in a critically endangered parrot, the Kakapo (Strigops habroptilus).

The shift from a diurnal to nocturnal lifestyle in vertebrates is generally associated with either enhanced visual sensitivity or a decreased reliance on vision. Within birds, most studies have focused on differences in the visual system across all birds with respect to nocturnality-diurnality. The critically endangered Kakapo (Strigops habroptilus), a parrot endemic to New Zealand, is an example of a species that has evolved a nocturnal lifestyle in an otherwise diurnal lineage, but nothing is known about its' visual system.

MRI of postmortem specimens of endangered species for comparative brain anatomy.

Many of the 5,500 threatened species of vertebrates found worldwide are highly protected and generally unavailable for scientific investigation. Here we describe a noninvasive protocol to visualize the structure and size of brain in postmortem specimens. We demonstrate its utility by examining four endangered species of kiwi (Apteryx spp.

Evolution of brain size in the Palaeognath lineage, with an emphasis on new zealand ratites.

Brain size in vertebrates varies principally with body size. Although many studies have examined the variation of brain size in birds, there is little information on Palaeognaths, which include the ratite lineage of kiwi, emu, ostrich and extinct moa, as well as the tinamous. Therefore, we set out to determine to what extent the evolution of brain size in Palaeognaths parallels that of other birds, i.

Kiwi forego vision in the guidance of their nocturnal activities.

Background: In vision, there is a trade-off between sensitivity and resolution, and any eye which maximises information gain at low light levels needs to be large. This imposes exacting constraints upon vision in nocturnal flying birds. Eyes are essentially heavy, fluid-filled chambers, and in flying birds their increased size is countered by selection for both reduced body mass and the distribution of mass towards the body core.