The environmental determinants of dispersal and migratory behaviour of long lived birds

In recent years, evidence has grown that the migratory behaviour of many bird species is changing in response to changing environmental conditions. In particular, non-migratory individuals have been reported in previously wholly migratory populations. These rapid changes in migratory behaviour provide an opportunity to understand the ontogeny of migratory behaviour and identify the mechanisms through which complex and highly evolved behaviours respond to changing environmental conditions. Changes in environmental conditions and in resource availability can alter the selection pressures operating on migratory behaviour, and individual strategies may differ according to the conditions individuals will experience. Long-lived birds may experience considerable changes in environment and resource availability during their life-time, hence it would be advantageous for individuals to be flexible and adopt the migratory strategy that best takes advantage of changing environmental conditions. This has rarely been observed and individuals tend to be consistent in the migratory strategy they adopt in early life. This project will examine the environmental conditions that determine the establishment of different individual migratory strategies. Individual level data is difficult to obtain since the environmental data is not available at the scale individuals experience it.

This project will involve tracking white storks (large, long-lived birds) and simultaneously monitoring the environmental conditions which individual birds experience. Our current GPS/GSM loggers can record accelerometer and temperature data but new sensors are needed to monitor other environmental parameters that may affect dispersal and movement (wind speed, direction, humidity). We will monitor how changes in environmental conditions will affect the movement, migratory behaviour and mortality of resident and migratory white storks.

Methods:
This project will benefit from the experience of previous work done with tracking white storks in Portugal and Spain and will be linked to an existing NERC POC for the development of new tracking devices to monitor the movement behavior of animals.
White storks are a good study system because they are large long-lived species likely to have adaptable behaviour because they experience variation in environmental conditions through their lives. We will track the movement of 40 juveniles and 20 adults and their movement in response to changes in environmental conditions. The birds will be trapped at the nest, their fitness, sex and age will be recorded. Movement characteristics (speed, direction, flight type and distance moved) will be related to the data obtained by the environmental sensors on the tracking devices and to ground cover on the locations where birds land.

Objectives:
- Identify the environmental determinants of dispersal and migratory behaviour, controlling for individual fitness, age and sex;
- Incorporate new sensors in existing dataloggers and create new prototypes that simultaneous monitor bird movement (GPS), behavior (accelerometer) and environmental parameters (e.g. temperature, wind speed, barometer)
- Determine the influence of environmental parameters in the demography of white storks including migration and over-winter survival, arrival date, nest-site selection, and breeding success.