LAB

Visual acuity. We estimate visual acuity using histological techniques. We are interested in two layers of the avian retina: photoreceptors (cones and rods) and retinal ganglion cells (communicate stimuli from the retina to the brain). We process retinas with two staining techniques and then take digital pictures on the microscope to later estimate the distance between neighboring cones and density of retinal ganglion cells.

Photoreceptor cell layer of House Sparrows

Retinal ganglion cell layer of European Starlings

Visual fields. We use an ophthalmic reflex technique to estimate the 3-D distribution of the different portions of the visual fields of birds (binocular, peripheral, blind area, and projection of the pecten). This technique has been used extensively by Prof. Graham Martin (University of Birmingham, United Kingdom). In fact, we recently acquired the visual field apparatus and got trained by Prof. Martin.

After a training session with Prof. Graham Martin

Megan Gall with our brand new Visual Field Apparatus

Distribution of motion detectors in the retina and avian color vision. We recently acquired a microspectrophotometer, which allows us to identify and map the different visual pigments in the avian retina that are associated to motion detection and the perception of colors (including UV). More info coming soon.

SEMI-NATURAL EXPERIMENTS

We conduct experiments in semi-natural conditions because they allow us to manipulate factors of interest while controlling for confounding variables and to record the behavior of animals (e.g., scanning, foraging, escape) from different angles (see video, 29 MB, Windows Media Player), which we use to measure targets of visual attention. We recently developed robot birds to investigate cause-effect relationships relative to the use of social information in foraging groups. We can manipulate the behavior of the robots with a computer and study the reaction of live individuals (see video, 2.6 MB, Windows Media Player). 

Experimental set-up to study the anti-predator behavior of species with different visual acuity

Our mobile "control room" to coordinate the different cameras.

Robots built with bird skins and connected to a digital control system

FIELD WORK

Despite the inter-disciplinary nature of our lab, we do considerable field work to survey bird and mammal populations and study their behaviors in natural conditions, such as vocalizations, anti-predator strategies, foraging, tolerance to disturbance, etc. We work with common as well as endangered species (e.g., South Western Willow Flycatcher, Belding's Savannah Sparrow). Here are some examples. 

Effects of the foraging behavior Western Gulls on the dynamics of sea urchins in the inter-tidal

Effects of recreational activities on Black-crowned Night Heron breeding behavior

Belding's Savannah Sparrow use of native and non-native vegetation in salt marshes in Southern California

MODELING

We are developing mathematical models to assess the effects of different types of visual systems in the transmission of anti-predator information in social contexts, and to predict the effects of recreational activities on the habitat use of species of conservation concern.