Respect other species - Field trip to Don Luis March

COLLETT TRUST FOR ENDANGERED SPECIES - Respect other species

FIELD TRIP TO DON LUIS 08-29 MARCH 2011

In March 2011, we spent 3 weeks at Don Luis with some experts from Durrell Trust who came to help with counting species. Dr. Amy Hall, the registrar from the Jersey trust was helping us and one of her fields of expertise is small mammal trapping. Kate Sharma who worked with Tamarinds at the trust and who is also chairman of the Jersey Bat Group was here to help us with particular accent on bat identification. We were also fortunate to have along Gregory Guida who is a wildlife photographer with many interesting techniques. He used a FLIR infra red camera to help us see mammals at night amongst his other gadgets.

We saw Marsh Deer in the garden most days as well as Grey foxes which were becoming a bit too regular. The water level was very low during the 3 weeks of survey due to the fact that there had been little rain since January. This made travel around the land easier for us and the amount of Caymans that we saw was staggering due to their being confined to small areas where there was water. As a result when the temperature was right we could see dozens of these iconic reptiles. We set up about 30 small/medium mammal traps but all we caught in them was one young fox. We had more success with the bat mist netting in which we caught 3 small/medium bats over the length of the survey.

We were puzzled by the fact that there were so many healthy looking predators such as foxes, raptors, caymans, crab-eating racoons, Geoffroy's cats, large snakes and potentially Maned Wolves but we rarely saw any prey. There must be mice and rats around (although fortunately not the introduced black or brown rats). We did come across a nest of young rats in a small island surrounded by water with the help of our ranger who has a keen eye and ear for these things. We put up a remote camera in this place but unfortunately later witnessed a fox finding the nest.

During the survey we were fortunate to have some welcome visitors - 2 young Marsh deer which were probably related. They stayed in our garden for about an hour, resting and eating and we managed to get some good photos. They were totally unbothered by us. We also had a Spectacled Cayman come and lie in our garden which was strange but it was probably looking for water.

Marsh Deer juveniles, Ciervo de los Pantanos - juveniles

We spent a day and night at Rincon del Socorro toward the end of March. This is a reserve 170km away by dirt road ,but only about 70km in a direct line. We tracked one of the Giant Anteaters and saw photographic evidence of Maned Wolves from the remote cameras that we have donated, which is encouraging. Report to follow and see page on photos taken by Gregory Guida.

Whistling Heron (Chiflon)

Please see below report from Kate Sharma and Dr Amy Hall.

The mist netting for bats yielded 3 bats which is less than we had hoped but these mammals are very difficult to trap. The first night we managed to catch a Hoary bat (Lasiurus spp) which was interesting. We were able to disengage it from the net relatively easily and release it safely after measuring and weighing it. Kate also caught 2 more bats - one was probably Eumops species and the other needs some work to identify.

We caught amphibians, interesting insects, and fish with a net.

Gregory is a fantastic photographer and has taken many pictures of bugs, fish as well as birds and mammals.

Results from the camera traps have been good and we have seen several Grey foxes, Crab-eating racoons, Capybara, Armadillos and Marsh Deer. We have one shot that looks very like a Maned Wolf but we would be very lucky indeed to come across such an illusive creature. See some of these infra-red photos on our webpage entitled 'Results from infra-red cameras'. See a selection of Gregory's photos on our webpage entitled - 'Photos from Gregory Guida'

We have had a lot of luck with reptiles which Gomez our ranger seems to regularly find. During the trip we saw and photographed a Parrot Snake, a Yellow Anaconda, a Leopard Keelback, a Cat-,eyed snake, a Bothyrops alternatus (very venemous) and a Boa constrictor. Have a look at our new webpage entitled Reptiles of the Ibera wetlands.

Bothyrops alternus

Pilot Study

- Bats Estancia Don Luis, Ituzaingo, Corrientes.

by Kate Sharma

Purpose of study

Estantica Don Luis is a former cattle ranch which has been reclaimed for conservation purposes. With the field station operational, we were invited to conduct a preliminary survey to identify the species of the immediate area.

A bird expert herself, the owners request was to focus on the mammal species present. This report covers the findings of the mist net study conducted immediately around the field station and immediate woodland.

The Study was conducted by Dr Amy Hall and Kate Sharma during the period of the 16th - 28th of March

All bat photographs were taken by and copyright to Gregory Guida.

Equipment

Series 700P (Polyester) Mist Net: Height 2.5m, Length 3m in combination with Telescopic mist net poles and Mist Net Mounting Set: Set A (for nets 3 to 15m long) produced by Ecotone from NHBS.comGloves (thick leather)Bat box Duet Bat detector

Method

Positioning of the nets and preparations (ie digging holes for the poles and putting in pegs for guide ropes) were done during the day.

Half an hour before sunset the net was erected and secured using guide ropes. This should not be done any earlier so as to minimise the risk of catching birds.

Depending on the position of the netting – if it was in view of the house continuous monitoring was implemented, but when in the wooded area, the net was checked approximately every 10 minutes in combination with the use of a bat detector pointed towards the net to ensure quick notification of catches between checks.

During the course of the study the net was placed in five positions around the main house. These are shown Diagram A.

The study was conducted over a 2 week period with trapping starting half an hour before sunset and finishing 3 hours after.

Upon capture, bats were realised by hand (although in extreme instance, sometimes cutting the net was essential for the swift and safe release of the bat.

The bat was then weighed, measured and photographed, with emphasis on any defining characteristics, (see below) to enable identification. This was conducted as swiftly as possible to ensure the animal suffered the minimum distress and released immediately afterwards.

Diagram A – Sketch Map indicating locations of mist net in numerical order

Results

Although a number of bats were seen around the site (both visually and using the detector) Only three individuals (all adults) were caught – they are as follows (all measurements are in mm)

Bat 1 - Male Lasiurus blossevilli or Hoary Bat

IUCN – Least concern (2008)

Caught in net 1

Forearm – 40mm

Weight – 10g

Distinguishing features: Furry tail Bright colouring

Bat 2 - Female Eptesicus furinalis – Argentine Brown Bat

IUCN – Least concern – 2008

Caught in Net 3

Forearm – 32

Weight 10g

Distinguishing features: Small feet Bald bottom Big ears with pointed tragus Free tail Dark colouring with frosted underbelly

Bat 3 – Female Eumops patagonicus – Patagonian Dwarf Bonneted Bat

IUCN – Least concern – 2008

Caught in net 5

Head & Body – 60

Total Tail - 29

Free Tail – 20

Hind Leg – 27.7

Forearm – 45

Ear – 12

Weight 17.5g

Distinguishing features: Dark Brown with pale underbelly Hairy Large feet Long free tail Large fleshy ears that meet in the middle

Conclusion

The Estantica don Luis is an exceedingly rich area for bats. In just a short amount of time three bats were caught in the mist net, but many more were seen flying around the field station and picked up on the detector. All three species are listed are of Least Concern on the IUCN Red Data list however that does not preclude the presence of rarer species. The forest fragments contain a number of mature trees suitable for roosting and the surrounding matrix of wetland provides an abundance of insect prey. The three bats caught were all insectivorous. It seems unlikely that fruit bat species would could be supported on the number of fruit trees available, however this should not be ruled out as groups of howler monkeys (Aloutta caraya ) do live in the same copses and rely on fruit as a large part of their diet.The study has shown that a variety of species, from different families coexist in the area and further study is definitely recommended.

Recommendations

Using a high quality bat detector, recordings can be made which would enable a non-invasive method of analysing species presence. We suggest using either a Peterson with a recording device attached, or for more inaccessible locations, an Anabat may be used for taking unmanned readings.

The recordings can then be analysed using appropriate media and using sound banks, identifications can be made.

This can be done with basic training and no licence would be required. If experienced personnel are available and a licence is issued, continuation of the mist netting would continue to provide interesting information. Suggestions for continuation of mist netting are as follows;

Initially we would suggest starting in the darker areas to the south coming around the west to the north of the house. These would be set up as per the pilot study; however we would suggest that the monitoring should continue throughout the night until the morning to allow the maximum chances of capture. This will require at least 2 scientists being present who are not also involved in daylight trapping regimes for other species as they were during the pilot.

Further positions could include the forest interior or during wetter months, around the pond (this was dried out during the majority of the survey). Nearby copses could also be investigated which would involve camping at the location.

If these are attempted however extreme care must be taken as these situations would increase the likelihood of encountering venomous snakes. The higher levels of insect activity should also be taken into account.

We would also suggest that a longer net may be advantageous, many bats were observed to be swerving out of the way of the net at the last minute. Whilst their ability to echolocate means that bats are usually quite good at avoiding nets, however a longer net maybe an advantage. A great increase in length would make it difficult to manage and would require more people for monitoring, however upgrading from a length of 3m to 6m (maybe having 2x 3m nets for greater flexibility) may increase catch numbers.

In terms of long term goals, the location of individual roosts although difficult maybe advantageous, as well as enabling counting of individuals in a group, it would enable informed decisions about species preferences. It could also be important if any trees need to be felled at any time.

In terms of landscape improvement, the creation of linear corridors between the copse behind the field station and adjoining patches of woodland would be particularly advantageous to a number of species including bats.

References

Barques, Giannini and Mares - Guide to the Bats of Argentina Oklahoma Museum of Natural History (1993)

Emmons L H - Neotropical Rainforest Mammals 2 edition University of Chicago Press (1997)

Redford K H & Eisenburg JF - Mammals of the Neotropics: Southern Cone - Chile, Argentina, Uruguay, Paraguay v. 2 (Mammals of Neotropics) University of Chicago Press; 2nd edition (1992)

Sutherland W - Ecological Census Techniques : A Handbook Cambridge University Press; 2 edition (2006)