Principal Ecologist Matt Hobbs recently presented a talk entitled “An Introduction to Bat Migration” to the Spurn Migration Festival in East Yorkshire. The talk gave details of BSG Ecology’s ongoing research project to look at patterns of bat activity (potentially indicating migration) at coastal sites around England and Wales and, in 2014, on North Sea ferry / freight routes. The event at Spurn is the first of its kind in the UK and this is the second year that it has been held. Matt’s talk was incorporated into a programme of events between 5-7 September that included guided migration watches, sea-watching, bird-ringing demonstrations, moth-trapping and a number of illustrated talks. Matt’s talk provided an introduction to bats and what is known of their migratory behaviour, with a focus on Europe, and also provided a summary of the findings of BSG’s ongoing study.
During his stay, Matt also left bat detectors out for two nights at the Observatory and the Church Field, and recorded a number of Nathusius’ pipistrelle (a species of bat known to be a long-distance migrant in continental Europe) passes from both locations. A Nathusius’ pipistrelle was also found in the seawatching hut at Spurn on the morning of 4 September. The bat, an adult female, appeared lethargic / exhausted and was taken into care. The bat was examined and identified by Matt Hobbs following his arrival the same evening and found to be in torpor. However, the bat was apparently uninjured, became much more active, and flew off vigorously when released later the same evening.
During the two days prior to the Nathusius’ pipistrelle records at Spurn there were significant arrivals of continental bird migrants along the east coast associated with the prevailing easterly airflow and high pressure over Scandinavia. It is possible that the bats crossed the North Sea in the same conditions.
Some ongoing research has involved the deployment of bat detectors on two ferry routes across the North Sea. Recent records from the DFDS Seaways Felixstowe-Vlaardingen freight ship have provided context with regard to the Nathusius’ pipistrelle record at Spurn: the species was recorded at 06:11 on 4 September and at 05:15-05:26 (possibly two bats) on 5 September. The timing of these recordings indicates that the ship was 3-4 hours east of Felixstowe and mid-way across the North Sea on both these days. All of the Nathusius pipistrelle calls recorded in 2014 from this ship have been close to dawn, which may indicate that these bats had not managed to cross the North Sea during the night and were trying to find a roost on the ship in order to avoid diurnal predators. In addition, a Leisler’s bat was recorded from the ship close to Felixstowe on the evening of the 5 September. This species is relatively scarce in Suffolk, is thought to be resident in the UK but is known to be a long-distance migrant on the European continent. It is possible that this record may refer to a migrant bat, but its proximity to the coast does not provide as clear cut evidence of migratory behaviour as the records of Nathusius’ pipistrelle at sea from the same vessel.
The report detailing the results of the North Sea ferry and freight vessel bat detector studies should be released before Christmas.
More information on the Spurn Migration Festival is available here.
Top photograph: Nathusius’ pipistrelle taken by Matt Hobbs