Heavy metals and selenium in feathers of great tits (Parus major) along a pollution gradient.

We evaluated the use of great tit (Parus major) feathers as biomonitors for heavy-metal pollution and tested whether there were differences in metal levels in feathers as a function of location, age (first year or older), or gender. In 1998 and 1999, we collected the outermost tail feathers of 185 great tits from four sites along a presumed pollution gradient and one reference site in Antwerp (Belgium) and analyzed them for calcium, selenium, and 13 heavy metals (silver, aluminum, arsenic, cadmium, cobalt, chromium, copper, iron, mercury, manganese, nickel, lead, and zinc). Silver, arsenic, cadmium, cobalt, copper, mercury, nickel, lead, selenium, and zinc concentrations were significantly higher closest to the pollution source (UM site) compared with the other four sites. Heavy-metal and selenium levels were on average 2 to 40 times higher at the UM site compared with the reference site. Aluminum, calcium, and iron levels were not significantly different among sites. We found no general age- or gender-related differences in metal levels except for arsenic and iron, where a significant interaction between site and gender was observed. Our results suggest that feathers of great tits might be useful biomonitoring tools because they reflect the environmental contamination by heavy metals well.

Non invasive in vivo anatomical studies of the oscine brain by high resolution MRI microscopy.

We describe in this paper an in vivo Magnetic Resonance Imaging (MRI) procedure that allows one to obtain three-dimensional high quality images of the entire brain of small passerine birds such as the canary with a slice thickness of 58 micron and an image resolution of 78 microns. This imaging procedure was completed in 70 min on anaesthetised birds that later recovered uneventfully and could be reused for subsequent additional imaging. To illustrate the high resolution and anatomical detail that can be achieved, examples of coronal images through the entire hypothalamus are provided in the same sectioning plane as the previously published canary brain atlas. The data set can be used to create sections in any desired plane and the entire data set can be viewed from any point of view in a volume rendered image. This provides a useful tool in understanding the three-dimensional organisation of the brain. Similar procedures can also be applied on fixed brains and might allow an even better anatomical resolution of images because time constrains no longer limit the duration of image acquisition. The non-invasive MRI technique enables to study neuroanatomical features with a high resolution and without killing the animal subjects so that measures can be obtained in a same individual both before and after an experimental treatment.