ORCID Profile
0000-0002-9142-6773
Current Organisation
Self Employed
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: California Digital Library (CDL)
Date: 03-05-2023
DOI: 10.32942/X2FG6R
Abstract: 1. Reproductive performance in birds can be affected by both social environment and small-scale environmental heterogeneity via food abundance, availability of nesting sites, and predation risk. However, to date, the best studies of effects of microhabitat variation on avian populations have been on northern hemisphere passerines using nestboxes, where birds have limited control over nest sites and have a comparatively simple social structure. 2. Here we utilise a multi-decade dataset on the superb fairy-wren, Malurus cyaneus, a southern hemisphere passerine with facultative cooperative breeding. We monitored territory characteristics, nest locations and breeding success, and used GIS to relate these to social organisation and a survey of vegetation characteristics throughout the study area.3. There was a long-term nearly two-fold decline in population density over the study period (1994-2015). This was associated with a corresponding decline in the mean number of helpers per group, and hence in the extent of cooperative breeding: in the first four years of the study (1994-1997), 56% of groups had at least one helper, but in the final four years (2012-2015), this was reduced to 28%. Mean territory size also increased (from 0.74ha in the first four years to 1ha in the final four years) such that on average, years with lower numbers of helpers per territory had larger territory sizes. However, helper number was positively correlated with territory size within years.4. Reproductive performance was related to microhabitat heterogeneity: fledgling production was lower and nest predation higher in territories with dense midstorey vegetation, possibly because avian predators using visual information to detect nests can conceal themselves from nesting birds. Predation during the nesting phase decreased over time, indicating that the population decline was not driven by increased predation.5. The causes of overall population decline remain to be determined, however our analyses have uncovered both microspatial patterns in nesting behaviour of birds, and temporal changes in population density and social group dynamics. From a methodological perspective, the study demonstrates the utility of GIS methods for investigating fine-scale habitat dynamics over time.
Publisher: Elsevier BV
Date: 03-2009
Publisher: Wiley
Date: 11-2003
DOI: 10.1111/J.1460-9568.2003.03017.X
Abstract: Principal neurons of the medial nucleus of the trapezoid body (MNTB) receive a synaptic input from a single giant calyx terminal that generates a fast-rising, large excitatory postsynaptic current (EPSC), each of which are supra-threshold for postsynaptic action potential generation. Here, we present evidence that MNTB principal neurons receive multiple excitatory synaptic inputs generating slow-rising, small EPSCs that are also capable of triggering postsynaptic action potentials but are of non-calyceal origin. Both calyceal and non-calyceal EPSCs are mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and N-methyl-d-aspartate (NMDA) receptor activation however, the NMDA receptor-mediated response is proportionally larger at the non-calyceal synapses. Non-calyceal synapses generate action potentials in MNTB principal neurons with a longer latency and a lower reliability than the large calyceal input. They constitute an alternative low fidelity synaptic input to the fast and secure relay transmission via the calyx of Held synapse.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Martine HAMANN.