Workshop in insect monitoring techniques in South Africa!

Mikkel Brydegaard, Anna Runemark and I have been collaborating over the last few years to study animal colour, dispersal and movement patterns, and to develop novel techniques for insect monitoring. We have compiled our knowledge and experience on these topics to create a 1-day workshop on Insect Monitoring Techniques at Stellenbosch University in South Africa.

 In the morning, Anna and I gave a lecture about what sort of questions biologists can answer using remote and optical sensing techniques. After this introduction, we went to the nearby nature reserve where Mikkel had two monitoring experiments prepared. 

Both setups consisted of a telescope, black termination box, and high frequency sampler (for wing beat detection), but differed from one another in that one made use of a quadrant detector with three spectral bands, which allows to estimate insect flight trajectories, while the other one was connected to a spectrophotometer for detailed colour assessment. These setups are attractive alternatives to the expensive laser radar equipment previously applied by our team for insect monitoring and can thus be used even by laboratories with less funding. 


The course participants got to take an active part in each step of the monitoring exercise, from the calibration of the instruments, interpretation of the data signals, to the catching and releasing of insects. After a hot but successful field exercise, we all went back to the university building to start a data analysis exercise. The course finished at 5pm, after which we gathered for a photo session outside. The activity got considerable local attention. The local newspaper will be covering the event monitoring and a passing high school teacher spontaneously brought his class to visit the experiment and let the students ask questions on the topic. In the next weeks, we will evaluate the data that we recorded during the day and share this with the park officials and all people that took part in the course. We think that the biologists and physicists that participated in this workshop found it useful and interesting to see how something like this can be carried out in practice, and this made it a rewarding experience all around. Greetings from Stellenbosch!

//Maren Wellenreuther 

 

Under-water and over-water foraging behaviour of a deep diving seabird

Common guillemots (N. Am. common murres, Sv. sillgrisslor, Uria aalge) are remarkable in their abilities to live at the interface between land, sea, and sky. During the breeding period, in pairs they raise a single chick on a rocky ledge, with each parent making many foraging trips out to sea to catch fish to feed their chick. A typical foraging trip may consist of a flight of over 10 km, followed by sequences of exceptionally deep dives to over 50 m water depths, followed by a flight back to the colony carrying a single fish in their bill for their hungry chick! Following this behaviour in detail has been challenging. Devices must withstand the great water pressure found deep down. Device weights and dimensions must be kept low to avoid impairing the guillemots' flight and diving too greatly. Then to observe these remarkably both aerial and aquatic birds, one must both track their geographical positions and their vertical movements underwater.

Fig. 1. GPS tagged guillemot brooding its chick (not visible) with partner to left.

In a new study (Evans et al. 2013) just published in Marine Ecology Progress Series, we give a detailed account of the foraging behaviour of guillemots breeding at the Swedish Baltic Sea island of Stora Karlsö, located off the west coast of Gotland. We used small GPS loggers in conjunction with time-depth-recorders (TDRs), allowing the tracking of both the guillemots' foraging flights and their remarkable dives.

We found a strong temporal pattern in activity (see figure). Foraging trips overnight were of longer duration than daytime foraging trips, this corresponded with crepuscular diving activity, with higher diving frequency around dawn and dusk, and reduced dive depths at these times. This likely corresponding to prey availability, with the birds' main prey species, herring (sv. sill, Clupea harengus) and sprat (sv. skarpsill, Sprattus sprattus) displaying a diel vertical migration, moving to surface waters at night. The longer duration overnight trips may allow the guillemots to fly out to a good foraging site in the evening, with some 'self-provisioning' (feeding for the adult) in the evening, followed at dawn by foraging for fish to return to the chick.



Fig. 2. An example trip from Figure 2 in the paper. By combining GPS and time-depth-recorders (TDR) we gained very detailed insights into the guillemots' foraging behaviour. (A) GPS track with different activities coloured (orange -flight, blue - water surface resting, purple - diving periods), (B) Diving, (C) Wet or dry state of TDR tag, (D) distance from nest, (E) GPS recorded speed.

Flight behaviour appeared to be strongly affected by winds, with outward flights having much greater ground-speeds (the speed that the murre moves relative to the land surface, cf. airspeed, the speed relative to the air) than the return inward flights. This pattern most likely owing to outward flights being aided by tail winds and inward flights by head winds. Most of these flights were along the same axis as the wind direction (i.e. either head- or tail-winds, but not side-winds), this may reflect a strategy to reduce wind-drift. For over the sea detection of wind drift is difficult, with the lack of fixed land marks. As with head- or tail-winds there will likely be lateral drift.

Finally foraging intensity, as measured by number of dives per a trip, and the number of dives per a diving bout (dives occur in sequences with short inter-dive interval), measure for Stora Karlsö guillemots was lower than that found in studies at other colonies, suggesting good foraging conditions.

This study was a collaboration between CAnMove researchers, Tom Evans and Susanne Åkesson, and researchers at the Stockholm Resilience Centre of Stockholm University; Olof Olsson and Martina Kadin.

/Tom

Evans TJ, Kadin M, Olsson O, Åkesson S (2013) Foraging behaviour of common murres in the Baltic Sea, recorded by simultaneous attachment of GPS and time-depth recorder devices. Mar Ecol Prog Ser 475:277–289.

Interesting and stimulating symposium on dispersal!

From Jan 30th to Feb 1st 2013, the symposium on "Causes and Consequences on Organism Dispersal" was held at Lund University hosted by BECC and CAnMove. We were honored by a large number of motivated participants (90 people) including 9 international speakers, 8 national speakers and 15 poster presenters. They introduced different approaches to understand, monitor and model the impact of dispersal, of a diverse range of taxa (from microbes to fish and marsupials), in a changing environment.

Some of the participants during the symposium - Group Picture (photo: Inger Ekström)

Discussions and talks highlighted the key role played by dispersal on the biodiversity and distribution of organisms on Earth. Discussions took place formally in the auditorium and continued during two dinners and a quiz on organism dispersal.

  

Organism dispersal is complex and depends on different parameters. For example, it is shaped by life history (Beth Okamura from Natural History Museum), animal personality (Julien Cote from University Paul Sabatier), and the interaction/competition between dispersers and native species (Wim van deer Putten from Netherland Institute of Ecology). It varies among scales (temporal and geographical scales, Wim Vyverman from Gent University). It also occurs during migration flight in birds Clark Rushing (Smithsonian Institution) and may be influenced in microbes by mass effect and/or species sorting (Eva Lindström from Uppsala University). The dispersal of an organism is often link to the dispersal of smaller attached organisms with important consequences on health (e.g. malaria, Staffan Bensch, Lund University) and community diversity (e.g. propagules dispersed by waterbirds, Andy Green, Doñana Biological Station). A theorical approach to integrate these parameters was presented by Jörgen Ripa (Lund University).

  

Monitoring dispersal is sometimes tricky and different approaches were discussed related to the size of the organism that disperses and the habitat: the use of airborne sampling (Jakob Löndahl from lund University), environmental DNA (Alice Valentini from Spygen), high polymorphic genetic markers to measure gene flow and population structure (Paul Bentzen from Dalhousie University) and the use of next generation sequencing (Sylvie Tesson from Lund University).

Landscape plays a crucial role on the movement of an organism (Paul Caplat from Lund University), acting as a resistance against free dispersal (Rachael Dudaniec from University of Queensland), and impacting the distribution, the survival and the persistence of populations (Johan Ekroos from Lund University). Zones of conservation and protection of some organisms are nowadays established based on models (Per Jonsson from Gothenburg University). However, one needs to integrate the life cycle, biology, animal personality, and the interactions with the environment and the native species, in order to delimit ‘real’ and ‘reliable’ reserves to save biodiversity.

Audience room during the symposium – Session I (photo: Giuseppe Bianco)

Overall it was a very informative and fun symposium, which brought together different domain of research questions in the area of organism dispersal. We ended the symposium with a world-cafe  - a series of discussions around a cup of coffee.

The organization committee - Sylvie Tesson, Karin Rengefors and Katarina Hedlund - would like to thank all of the participants of the symposium for their active discussions on organism dispersal in a changing environment, and all delegates who helped us during the symposium!

We will now begin to work on Summary and Forum papers in order to share our discussion with the scientific community, including some of the exciting researches we heard about at the symposium and novelties and future issues we judged important to pinpoint. Please keep in touch to discuss and read the upcoming papers…

//Sylvie Tesson

Post-doc position in Denmark: analysis of animal movements and distributions

Aarhus University in Roskilde is seeking a highly talented researcher with strong analytical skills to conduct statistical/computational analysis of animal tracking data for birds and marine mammals in arctic and temperate areas. Read more