Do Zebra Finch Parents Fail to Recognise Their Own Offspring?

Individual recognition systems require the sender to be individually distinctive and the receiver to be able to perceive differences between individuals and react accordingly. Many studies have demonstrated that acoustic signals of almost any species contain individualized information. However, fewer studies have tested experimentally if those signals are used for individual recognition by potential receivers. While laboratory studies using zebra finches have shown that fledglings recognize their parents by their “distance call”, mutual recognition using the same call type has not been demonstrated yet. In a laboratory study with zebra finches, we first quantified between-individual acoustic variation in distance calls of fledglings. In a second step, we tested recognition of fledgling calls by parents using playback experiments. With a discriminant function analysis, we show that individuals are highly distinctive and most measured parameters show very high potential to encode for individuality. The response pattern of zebra finch parents shows that they do react to calls of fledglings, however they do not distinguish between own and unfamiliar offspring, despite individual distinctiveness. This finding is interesting in light of the observation of a high percentage of misdirected feedings in our communal breeding aviaries. Our results demonstrate the importance of adopting a receiver's perspective and suggest that variation in fledgling contact calls might not be used in individual recognition of offspring.

High-dose intravenous corticosteroid pulse therapy in alopecia areata: own experience compared with the literature

BACKGROUND: Seven prospective studies including 193 patients have been published on high-dose intravenous corticosteroid pulse therapy in alopecia areata (AA).We compare these data with a retrospective analysis of our own consecutive patients. PATIENTS AND METHODS: Between 1998 and 2002,25 patients with severe AA were treated at the Department of Dermatology, University of Bern, with infusions of 500 mg methylprednisolone on 3 consecutive days.In addition to the inpatient records, in 2004 all patients were followed up by a questionnaire. RESULTS: Four of 10 patients with multifocal AA and 3 of 9 patients with ophiasis-type AA had full re-growth of hair, whereas all 6 patients with AA totalis/universalis failed to respond. CONCLUSION: Intravenous corticosteroid pulse therapy may be helpful in the treatment of multifocal and ophiasis-type AA. Patients with an initial episode of short duration have better chances for success.

Antipredator defences of young are independently determined by genetic inheritance, maternal effects and own early experience in mouthbrooding cichlids.

1. Predation is a prime force of natural selection. Vulnerability to predation is typically highest early in life, hence effective antipredator defences should work already shortly after birth. Such early defences may be innate, transmitted through non-genetic parental effects or acquired by own early experience. 2. To understand potential joint effects of these sources of antipredator defences on pheno- typic expression, they should be manipulated within the same experiment. We investigated innate, parental and individual experience effects within a single experiment. Females of the African cichlid Simochromis pleurospilus were exposed to the offspring predator Ctenochromis horei or a benign species until spawning. Eggs and larvae were hand-reared, and larvae were then exposed to odour cues signalling the presence or absence of predators in a split-brood design. 3. Shortly after independence of maternal care, S. pleurospilus undergo a habitat shift from a deeper, adult habitat to a shallow juvenile habitat, a phase where young are thought to be par- ticularly exposed to predation risk. Thus, maternal effects induced by offspring predators pres- ent in the adult habitat should take effect mainly shortly after independence, whereas own experience and innate antipredator responses should shape behaviour and life history of S. pleurospilus during the later juvenile period. 4. We found that the manipulated environmental components independently affected different offspring traits. (i) Offspring of predator-exposed mothers grew faster during the first month of life and were thus larger at termination of maternal care, when the young migrate from the adult to the juvenile habitat. (ii) The offspring’s own experience shortly after hatching exerted lasting effects on predator avoidance behaviour. (iii) Finally, our results suggest that S. pleuro- spilus possess a genetically inherited ability to distinguish dangerous from benign species. 5. In S. pleurospilus, maternal effects were limited to a short but critical time window, when young undergo a niche shift. Instead, own environmental sampling of predation risk combined with an innate predisposition to correctly identify predators appears to prepare the young best for the environment, in which they grow up as juveniles.