Revisiting a classic hybrid zone: rapid movement of the northern flicker hybrid zone in contemporary times

Natural hybrid zones have provided important insights into the evolutionary process, and their geographic stability/instability over time can help to disentangle the underlying biological processes that maintain them. Here, we leverage replicated sampling of an identical transect across the hybrid zone between yellow-shafted and red-shafted flickers to assess its stability over ~60 years (1955-1957 to 2016-2018). Using a plumage scoring approach that we validate with independent multispectral photography, we identify a ~73 km westward shift in the hybrid zone center towards the range of the red-shafted flicker but no associated changes in width. By integrating previous work in the same geographic region, it appears likely that this movement has occurred rapidly in the years since the early 1980s, prior to which the hybrid zone had remained stable over the previous century. This recent, rapid movement may be related to changes in climate or land management in contemporary times.

All-Dielectric Meta-Surface for Multispectral Photography by Theta Modulation

The traditional theta modulator encodes input information by superimposing Ronchi sub-gratings, which is extremely easy to cause spatial channel overlap that results in bands mixing. In this case, we present an all-dielectric theta modulation meta-surface with a new encoding method, which separates red, green, blue, and achromatic spatial channels on the focal plane. The meta-surface ensures that the positions of focal points are relatively consistent while focusing energy into the sub-wavelength regions. Our study offers a way to facilitate device miniaturization and system integration, which may have an important application in compact multispectral photography only with one detector.

Progress of remote sensing in Australia

During the past year multispectral photography and thermal infra-red scanning have been introduced to the region. The Cartwright multilens camera and the Daedalus thermal scanner have opened entirely new remote sensing horizons to consumers including government agencies, mining companies, forestry departments and municipal authorities. Much of the introduction has been via comprehensive test programmes over well known and documented features. Multispectral photography has been successfully used in several Queensland and Tasmanian mining areas as an aid to geological mapping, and by highway authorities in New South Wales. Thermal infra-red scanning has been carried out in the Territory of Papua New Guinea in search for geothermal areas and has proved highly successful in the search for upwelling fresh water into the ocean along coastal areas ultimately for a source of fresh water. Pollution studies involving oil slicks, sewerage, thermal pollution and illegal releasing of industrial waste have taken place in and around major population centres on the east coast using thermal detection techniques. Undoubtedly one of the major contributions thermal infra-red scanning has achieved is in the mineral exploration field. The large arid regions of Australia lend themselves well to presunrise scanning, where as a direct result of the work undertaken, significantly large new mineral discoveries have been made. Additional research and development further into the remote sensing field are taking place in Universities, quasi-governmental agencies and in the private sector like ourselves. The future looks bright for remote sensing in this part of the world and through same are continuing to further improve the environment we live in.