The effect of food quality during growth on spatial memory consolidation in adult pigeons

Poor environmental conditions experienced during early development can have negative long-term consequences on fitness. Animals can compensate negative developmental effects through phenotypic plasticity by diverting resources from non-vital to vital traits such as spatial memory to enhance foraging efficiency. We tested in young feral pigeons (Columba livia) how diets of different nutritional value during development affect the capacity to retrieve food hidden in a spatially complex environment, a process we refer to as “spatial memory”. Parents were fed either with high- or low-quality food from egg laying until young fledged, after which all young pigeons received the same high quality diet until the memory performance was tested at 6 months of age. The pigeons were trained to learn a food location out of 18 possible locations in one session, and then their memory of this location was tested 24 hours later. Birds reared with the low-quality diet made fewer errors in the memory test. These results demonstrate that food quality during development has long-lasting effects on memory, with moderate nutritional deficit improving spatial memory performance in a foraging context. It might be that under poor feeding conditions resources are redirected from non-vital to vital traits, or pigeons raised with low-quality food might be better in using environmental cues like the position of the sun to find back where food was hidden

A toxic diet: transfer of contaminants to offspring through a parental care mechanism

The transfer of maternal contaminants to offspring during oogenesis and gestation is documented in many animals, and in mammals, contaminants may pass from mother to offspring during lactation. Although other non-mammalian vertebrates provide parental care in the form of nutritive secretions for offspring to feed from, the potential for toxicant transfer during non-mammalian parental care is rarely considered. The discus fish, Symphysodon spp., employs an unusual parental care strategy where fry feed on parental epidermal mucus for several weeks after hatching. This strategy has the potential to act as a method of contaminant transfer. In discus adults, both waterborne and dietary toxicants are sequestered and secreted into their epidermal mucus, the food on which fry depend. To determine whether parents could channel these contaminants directly to offspring, we exposed parents to aqueous cadmium (Cd) and recorded the subsequent feeding behaviour and Cd content of fry. Fry continued to feed normally from contaminated mucus and accumulated significant tissue concentrations of Cd. In conclusion, this parental care mechanism of the discus fish can expose offspring to harmful contaminants during the sensitive early stages of life and highlights that parent to offspring contaminant transfer after birth may be more widespread than previously thought