| 1. |
- Weber, Thomas, et al.
(author)
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Flight feather shaft structure of two warbler species with different moult schedules: a study using high-resolution X-ray imaging
- 2010
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In: Journal of Zoology. - : Wiley. - 0952-8369 .- 1469-7998. ; 280:2, s. 163-170
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Journal article (peer-reviewed)abstract
- Plumage constitutes a significant component of the somatic investment of birds. A detailed investigation of feathers and moult can help to uncover trade-offs involved in somatic investment decisions, the sources of some of the costs birds have to pay and the potential fitness consequences. We used micro-computed tomography imaging to study the second moment of area, a structural parameter that is one determinant of bending stiffness and the cortex volume of flight feather shafts of two sister taxa, the willow warbler Phylloscopus trochilus, a migratory species with two annual moults, and the chiffchaff Phylloscopus collybita, a migrant with one annual post-nuptial moult. Juvenile and adult willow warbler and chiffchaff feathers, all grown on the breeding grounds, are structurally very similar to each other. Willow warbler feathers grown during moult on the wintering grounds, however, have a significantly higher second moment of area and a significantly larger cortex volume than all the other feather types. We discuss the possibility that the seasonal variability of willow warbler feathers may be an adaptive structural reflection of a moult-migration strategy that has allowed this species to occupy large breeding and wintering ranges.
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| 2. |
- Bowlin, Melissa, et al.
(author)
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Grand Challenges in Migration Biology
- 2010
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In: Integrative and Comparative Biology. - : Oxford University Press (OUP). - 1540-7063 .- 1557-7023. ; 50:3, s. 261-279
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Conference paper (peer-reviewed)abstract
- Billions of animals migrate each year. To successfully reach their destination, migrants must have evolved an appropriate genetic program and suitable developmental, morphological, physiological, biomechanical, behavioral, and life-history traits. Moreover, they must interact successfully with biotic and abiotic factors in their environment. Migration therefore provides an excellent model system in which to address several of the "grand challenges" in organismal biology. Previous research on migration, however, has often focused on a single aspect of the phenomenon, largely due to methodological, geographical, or financial constraints. Integrative migration biology asks 'big questions' such as how, when, where, and why animals migrate, which can be answered by examining the process from multiple ecological and evolutionary perspectives, incorporating multifaceted knowledge from various other scientific disciplines, and using new technologies and modeling approaches, all within the context of an annual cycle. Adopting an integrative research strategy will provide a better understanding of the interactions between biological levels of organization, of what role migrants play in disease transmission, and of how to conserve migrants and the habitats upon which they depend.
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| 3. |
- Bowlin, Melissa, et al.
(author)
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The effects of geolocator drag and weight on the flight ranges of small migrants
- 2010
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In: Methods in Ecology and Evolution. - 2041-210X. ; 1:4, s. 398-402
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Journal article (peer-reviewed)abstract
- 1. Researchers are currently placing hundreds of geolocators on migratory animals. Return rates for some small birds carrying these devices have been lower than expected, potentially because geo- locators increase drag during flight. 2. We measured the drag of three different geolocators (1 2g BAS-MK10, 1 0 g SOI-GL10 09 and 0 5 g SOI-GL05 10) in backpack-style harnesses on two preserved bird bodies in a wind tunnel.We then used these measurements to estimate the effects of this drag on the flight ranges of several small migratory birds. 3. Both theBAS-MK10 and SOI-GL05 10 significantly increased drag; the drag was also consider- ably higher when a geolocator was attached between the wings (wing harness) than on the rump (leg-loop harness). 4. The effects of the increased drag of these devices on the predicted flight ranges of birds were simi- lar to the effects of their weight and may thus explain the results of previous studies that showed decreased return rateswhen using geolocators and other tracking devices. 5. We recommend that researchers and manufacturers work to minimize the drag of geolocators and other externally attached tracking or data collection devices on flying and swimming animals. This can be accomplished with geolocators by attaching devices above birds rumps instead of between their wings and flattening the devices to reduce their height.
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| 4. |
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| 5. |
- Knudsen, Endre, et al.
(author)
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Challenging claims in the study of migratory birds and climate change.
- 2011
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In: Biological Reviews. - 1469-185X. ; 86, s. 928-946
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Journal article (peer-reviewed)abstract
- Recent shifts in phenology in response to climate change are well established but often poorly understood. Many animals integrate climate change across a spatially and temporally dispersed annual life cycle, and effects are modulated by ecological interactions, evolutionary change and endogenous control mechanisms. Here we assess and discuss key statements emerging from the rapidly developing study of changing spring phenology in migratory birds. These well-studied organisms have been instrumental for understanding climate-change effects, but research is developing rapidly and there is a need to attack the big issues rather than risking affirmative science. Although we agree poorly on the support for most claims, agreement regarding the knowledge basis enables consensus regarding broad patterns and likely causes. Empirical data needed for disentangling mechanisms are still scarce, and consequences at a population level and on community composition remain unclear. With increasing knowledge, the overall support ('consensus view') for a claim increased and between-researcher variability in support ('expert opinions') decreased, indicating the importance of assessing and communicating the knowledge basis. A proper integration across biological disciplines seems essential for the field's transition from affirming patterns to understanding mechanisms and making robust predictions regarding future consequences of shifting phenologies.
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| 6. |
- Liedtke, H. Christoph, et al.
(author)
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Alarm pheromones and chemical communication in nymphs of the tropical bed bug Cimex hemipterus (Hemiptera: Cimicidae)
- 2011
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:3, s. e18156-
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Journal article (peer-reviewed)abstract
- The recent resurge of bed bug infestations (Cimex spp.; Cimicidae) and their resistance to commonly used pesticides calls for alternative methods of control. Pheromones play an important role in environmentally sustainable methods for the management of many pest insects and may therefore be applicable for the control of bed bugs. The tropical bed bug, Cimex hemipterus, is a temporary ectoparasite on humans and causes severe discomfort. Compared to the common bed bug, Cimex lectularius, little is known about the chemical signalling and pheromone-based behaviour of the tropical species. Here, we show that the antennal morphology and volatile emission of C. hemipterus closely resembles those of C. lectularius and we test their behavioural responses to conspecific odour emissions. Two major volatiles are emitted by male, female and nymph C. hemipterus under stress, (E)-2-hexenal and (E)-2-octenal. Notably, nymph emissions show contrasting ratios of these compounds to adults and are further characterized by the addition of 4-oxo-(E)-2-hexenal and 4-oxo-(E)-2-octenal. The discovery of this nymph pheromone in C. hemipterus is potentially the cause of a repellent effect observed in the biotests, where nymph odours induce a significantly stronger repellent reaction in conspecifics than adult odours. Our results suggest that pheromone-based pest control methods developed for C. lectularius could be applicable to C. hemipterus, with the unique nymph blend showing promising practical properties.
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