The variability of juvenile dispersal in an opportunistic raptor

The juvenile dispersal of raptors is a crucial stage that stretches from parental independence to the establishment of the first breeding area.Between 2012 and 2020,44 juvenile red kites Milvus milvus from the Spanish breeding population were tagged using GPS telemetry to study their dispersal.Juveniles left the parental breeding area at the end of their first summer and performed wandering movements throughout the Iberian Peninsula,returning to the parental breeding area the following year,repeating the same pattern until they settled in their first breeding area.We analyzed the mean distance from the nest,the maximum reached distances,and the traveled distances(daily and hourly)during the first 2 years of dispersal and compared them.Despite the high individual variability,variables describing the dispersal movements of juveniles showed a decreasing trend during the second dispersal year:80% of individuals reached a shorter maximum distance in the second year,70% decreased their mean distance to the nest,65% decreased their hourly traveled distances,and 50% decreased their daily traveled distances.On the other hand,the red kites usually combined wandering movements with the establishment of temporary settlement areas(TSA).The average duration of settlement in the TSAs was 75±40 days(up to 182 days)and was located at 182±168 km from the nest.In those areas,juveniles used 781.0±1895.0 km^(2)(KDE 95%).Some of the TSAs were used by several individuals,which suggests that these areas might be good targets for conservation in future management plans.

Telemetry research on elusive wildlife: A synthesis of studies on giant pandas

Telemetry studies that track animals through space and time can lead to advances in scientific understanding that are vital in conservation efforts.For example,telemetry studies of the giant panda(Ailuropoda melano­leuca)have shed light on many aspects of panda biology,but small sample sizes in each separate study make it difficult to draw broad conclusions.To overcome this problem we conducted the first synthesis of all 5 pan­da telemetry studies conducted to date.Using these data we investigated patterns in 6 main topics:home range,space-use interactions,core areas,movement patterns,seasonal migration and natal dispersal.We found that panda home range sizes do not vary between 2 main mountain ranges(Qionglai and Qinling),as was previously believed.Our results also suggest that female pandas increase their movement in the mating season:a behavior typically attributed only to males.We found and summarized telemetry and genetic evidence for female natal dispersal in the giant panda.Our synthesis highlights the need for additional research relating panda behavior to human disturbance factors,and can aid future studies on giant pandas as well as other species.

Research progress in avian dispersal behavior

Dispersal,defined as a linear spreading movement of individuals away from others of the population is a fundamental characteristic of organisms in nature.Dispersal is a central concept in ecological,behavioral and evolutionary studies,driven by different forces such as avoidance of inbreeding depression,density-dependent competition and the need to change breeding locations.By effective dispersal,organisms can enlarge their geographic range and adjust the dynamic,sex ratio and genetic compositions of a population.Birds are one of the groups that are studied intensively by human beings.Due to their diurnal habits,diverse life history strategies and complex movement,birds are also ideal models for the study of dispersal behaviors.Certain topics of avian dispersal including sex-biased,asymmetric dispersal caused by differences in body conditions,dispersal processes,habitat selection and long distance dispersal are discussed here.Bird-ringing or marking,radio-telemetry and genetic markers are useful tools widely applied in dispersal studies.There are three major challenges regarding theoretical study and methodology research of dispersal:(1)improvement in research methodology is needed,(2)more in-depth theoretical research is necessary,and(3)application of theoretical research into the conservation efforts for threatened birds and the management of their habitats should be carried out immediately.