Female Zebra Finches smell their eggs

Golüke S, Dörrenberg S, Krause ET, Caspers B. Female Zebra Finches smell their eggs. PLOS ONE. 2016;11(5): e0155513.Parental investment in unrelated offspring seems maladaptive from an evolutionary perspective, due to the costs of energy and resources that cannot be invested in related offspring at the same time. Therefore selection should favour mechanisms to discriminate between own and foreign offspring. In birds, much emphasis has been placed on understanding the visual mechanisms underlying egg recognition. However, olfactory egg recognition has almost been completely ignored. Here, we investigated whether female zebra finches (Taeniopygia guttata) are able to discriminate between their own and a conspecific egg based on olfactory cues alone. Zebra finches are colonial—breeding songbirds. Eggs are monomorphic, i.e. without any spotting pattern, and intraspecific brood parasitism frequently occurs. In a binary choice experiment, female zebra finches were given the choice between the scent of their own and a conspecific egg. After the onset of incubation, females chose randomly and showed no sign of discrimination. However, shortly before hatching, females preferred significantly the odour of their own egg. The finding that females are capable to smell their own egg may inspire more research on the potential of olfaction involved in egg recognition, especially in cases where visual cues might be limited

Higher taxes on less elastic goods? Evidence from German municipalities

German municipalities have substantial autonomy in setting taxes on two distinct tax bases: business profits and property values. We use this setting and a two-step approach to explore whether implemented tax policy is consistent with the seminal inverse-elasticity rule. First, we estimate the tax elasticity of the two tax bases using event-study and generalized differences-in-differences methods based on the universe of municipalities in 1995–2010. Second, we compare the ratio of the observed tax rates for the two tax bases to the ratio of their estimated elasticities. We find that property is not very responsive to variation in tax rates, whereas business profits respond significantly. While this would suggest that property should be taxed at a higher rate, the data show that this not the case: most municipalities impose relatively higher rates on business profits. This suggests that municipality-level taxation in Germany is inconsistent with the inverse-elasticity rule. We provide suggestive evidence that this finding is explained by politician's imprecise expectations about revenue elasticities as well as re-election concerns

Data from: Female zebra finches smell their eggs

Golüke S, Dörrenberg S, Krause ET, Caspers B. Data from: Female zebra finches smell their eggs. Dryad Data; 2016.Parental investment in unrelated offspring seems maladaptive from an evolutionary perspective, due to the costs of energy and resources that cannot be invested in related offspring at the same time. Therefore selection should favour mechanisms to discriminate between own and foreign offspring. In birds, much emphasis has been placed on understanding the visual mechanisms underlying egg recognition. However, olfactory egg recognition has almost been completely ignored. Here, we investigated whether female zebra finches (Taeniopygia guttata) are able to discriminate between their own and a conspecific egg based on olfactory cues alone. Zebra finches are colonial - breeding songbirds. Eggs are monomorphic, i.e. without any spotting pattern, and intraspecific brood parasitism frequently occurs. In a binary choice experiment, female zebra finches were given the choice between the scent of their own and a conspecific egg. After the onset of incubation, females choose randomly and showed no sign of discrimination. However, shortly before hatching, females preferred significantly the odour of their own egg. The finding that females are capable to smell their own egg may inspire more research on the potential of olfaction involved in egg recognition, especially in cases where visual cues might be limited

Data Egg recognition

Raw data of the olfactory choice test.This file contains the time individuals spent in each preference zone, the ID of the test subjects, weight and origin of the used eggs

Time scale of the experiment.

<p>The time period of egg laying (4–5 days in this dataset) is followed by the time of incubation. Zebra finch chicks hatch after an average of 14 days. The odour preference test was performed on day 3 and 10 after clutch completion.</p

Do infants understand false beliefs? We don't know yet – A commentary on Baillargeon, Buttelmann and Southgate's commentary

The commentary by Baillargeon, Buttelmann and Southgate raises a number of crucial issues concerning the replicability and validity of measures of false belief in infancy. Although we agree with some of their arguments, we believe that they underestimate the replication crisis in this area. In our response to their commentary, we first analyze the current empirical situation. The upshot is that, given the available evidence, it remains very much an open question whether infants possess a rich theory of mind. We then draw out more general conclusions for future collaborative studies that have the potential to address this open question