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lunes, 25 de julio de 2011

Plots, physiology, and pair bond doubts

Research conducted by Greg Goodfellow, our behavioural intern, is not only beginning to bare fruit but has also thrown up some surprising, yet intriguing, records. He is working his way through the required data collection from each of the 9 measured locations within each of his 4 study groups. At present, although not yet statistically tested, it appears Greg is correct on some of his hypotheses over white-rumped tanager duets, territorial, and mate defence behaviours.
As there has been little, if any, previous work conducted on these birds it was always likely Greg would observe and record surprising incidences we would class as ‘unusual’. Of course these events are almost certainly not unusual. Rather it is a testament to how poorly we understand these Cerrado dwelling animals. For example, recently Greg observed and recorded some ‘unusual’ social behaviour within one of his study groups. On one occasion he recorded the resident male dueting with two different females at two different times. Furthermore, within the same group, Greg later recoded the same male dueting with two females at the same time. These observations underline not only how little we know about this species but also how flexible animal social systems can often be. Currently white-rumped tanagers are classified as a monogamous pair-bonded species. Greg’s recent records place question marks over the current opinion and may suggest higher and more direct levels of same sex competition or multiple group members taking part in synchronised song. Genetic data will cast more light on this issue.

Our botany intern Georgina Snelling is now two weeks into her field investigation on the factors affecting fern abundance, diversity, and distribution within the Para la Tierra reserve. Over the last 14 days Georgina has successfully measured and GPS’ed three 100m x 100m survey plots in each of her study habitats – Monte seco (dry forest), Atlantic forest, Cerrado, and riparian. This gives her a total of 12 plots to collect data from. Additionally, in the last two weeks Georgina has found two new fern species that she was previously unaware of, thereby adding to the known diversity within the reserve.

Aimee Oxley continues to press ahead with her Masters research into the affect of habitat disturbance on small mammals. Recently she has been trapping a higher than normal rate of the rarer species of Atlantic forest small mammals, for example Oligorysomys nigripes and Oligorysomys fornesi. Her research is also showing that weather and climatic conditions do have a distinct affect on her capture rate. During our recent warm and dry spell the number of daily captures fell from an average of over 15 to under 5. However, when we recently experienced a couple of storms the capture rate rocketed again. Currently the opinion is that during wet and/or cold conditions small mammals will be more likely to seek out shelter, and traps are a good form of shelter.


Behaviour among Cyanocorax chrysops (plush-crested jays)
As traditional methods of bird catching, such as mist netting, have failed with the Plush-crested jays we are now going to begin building custom cage traps. These will include bait at one end with a trigger system to close the door either when the bird pecks at the bait or steps into a trip wire. Furthermore we are honing in on what foods will tempt the jays into the traps. Our local forest guards have suggested that these jays have a particular liking for eggs and peanuts. So I will combine these two foods with the cultivated maggots to try and produce an irresistible plata.
I am now into the last two weeks of data collection for this initial phase of the project. Once this has been completed the focus for this project will switch to producing the first behavioural publication of Plush-crested jays and also catching and fitting individual leg rings to all group members. Then this project can progress to more complex issues.


Social and ecological factors among Clyomys laticeps (broad-headed spiny rat).

As I write the final round of root sampling is drying in the oven. In 3 days from now we will be in a position to either confirm or reject our hypothesis on water content as a factor for the apparent relationship Clyomys holds with a particular Cerrado bush. The root systems for all three of the sample bush species are unusual. None of these species, and hence probably many more Cerrado species, exhibit a tap root. What they do show is an extensive and large network of lateral long roots that sometimes stretch up to 5 meters away from the above ground section. This is seen even for very small bushes that appear to be in the primary stages of growth. A possible explanation for these observations is that many, if not all, of the Cerrado flora species can preserve their root systems during the natural fires that occur in this habitat. By doing this the plant essentially stays alive and can re-sprout once the fires have succumbed. Over a number of years of doing this the plants can continue to grow their roots without loosing them.
As I said in my last blog we are preparing to look at nutrient and compound levels in these bushes as an alternative explanation for the perceived preference Clyomys has for a particular species. Along with this we plan to dissect a Clyomys specimen from our museum to see if this species has a derived adaptation in the kidneys for retaining water. Trapping the Clyomys will begin in early August.

Until next time ill say goodbye.

Best wishes,

Luke

I’ve dug myself a hole…but have a tail with a happy ending.

Well actually I’ve dug myself 50 holes, and I have to be honest I didn’t actually do much digging (thanks boys!). However I am now the proud owner of 5 pit fall trap line arrays and I am finding some really cool herps. One of my newest lines is in a field of long grass and cacti (you know the sort, the wild wild west style cacti!) anyway within hours of digging in the buckets I caught an Amevia amevia – a lovely very colourful lizard - which is yet another new record for Laguna Blanca. And its not only reptiles and amphibians I’m getting in my new traps; yesterday I found a tiny baby opossum politely waiting for me to come along and let it go. The cute factor was quite high it has to be said!

It’s not only in the trap lines where I’m finding things though, in the last few days I have seen 2 massive snakes, neither of which we have in our museum… and neither I actually managed to catch either (sigh!). However I did manage to get the snake that was on Aimee’s transect and am happy to report that on closer inspection it wasn’t a deadly Bothrops but merely a rattlesnake (!), still highly venomous but not nearly as aggressive. Better still we have enough specimens of rattlesnakes so I was able to relocate it into another part of the forest where it can live out its days being no harm to anyone.

On a slightly sadder note we said goodbye to Claire, Jamie and Joe last night; three amazing, hardworking and flexible volunteers that will be sorely missed. It has to be admitted their departure could have gone a bit more smoothly. The car was all packed and we were ready to go when it became apparent a passport had gone AWOL! However, after much rummaging it was eventually found again (phew!). Then, as we were driving out of the reserve (its pitch black by now!) we bumped over something. “POP - FIZZ” is not a sound you want to hear when you are in the middle of nowhere with a flight to catch (or, in my case, get volunteers to). A front tyre had burst and our hearts sank. However all was not lost (it never is) and we had a plan B. A quick call to Karina and within ½ hour Luke arrived on the motoloco and sped off into the night with the volunteers all piled onto the back. Not the warmest or most comfortable of trips but they all got to the bus stop in plenty of time for their onward journeys. Which just goes to show that even when disaster strikes there is always a solution and never any need to panic!

I then returned to the house to find it over run with army ants- hurrah!

See you next time folks

Helen

lunes, 11 de julio de 2011

Mist nets, maggots, and moisture in roots

Here at Laguna Blanca we have finally come out of the prolonged cold spell we were enduring. It’s nice to have the sun back.
Greg Goodfellow’s investigation into aggressive reactions among white-rumped tanagers (Cypsnagra hirundinacea) is now in full swing. Each morning before first light he heads out onto the Cerrado to set up so that he can begin taking data as soon as his birds wake up. The dummy birds are also now making an appearance but there were a few slip ups when practicing launching them into trees.
Unfortunately Greg reported today that he thinks one of the females from one of his groups might have died. He did not see her and only the male was calling back to his vocal experiments. As sad as this is Greg may well be able to make something positive out of this change in demography. Having one of his groups with only one adult will provide an interesting opportunity for comparative analysis. However, perhaps she will return tomorrow.

Georgina Snelling begins her fieldwork tomorrow. Over the last few days she has been ‘keying out’ all of the species that she needs to be familiar with and able to identify. We also took a drive through all of the Cerrado to locate and finalise where she will measure out her plots so that she can begin surveying and recording the botanical dynamics of this little studied ecosystem. After some GPS training tomorrow morning she will be ready to launch the practical side of her study. Seeing as she has had her head in books for days now I think Georgina is looking forward to getting out in the field and executing her research.

Aimme Oxley’s research into the affect of disturbances on small mammal abundance and diversity has also been successfully launched. Her first capture-mark-recapture session was 6 days ago and she appears to be getting a healthy amount of individuals and data. As she began trapping while we still had the cold weather Aimme was concerned the captive animals would get too cold. Therefore she placed a good amount of bedding in each of her 260 traps.
Sex differences is one of the areas Aimme will compare. However these animals can be difficult to sex so Project Coordinator (and experienced small mammal trapper) Karina Atkinson had a session in the field with Aimme to teach her how to properly sex individuals. This was important to avoid mistakes in her data.

Behaviour among Cyanocorax chrysops (plush-crested jays)

My first paper for publication on the Plush-crested jays is under way. After this initial publication the project will move on to address more complex behavioural aspects of these birds. In order to investigate complex social dynamics each individual of each group will need a leg ring to distinguish themselves from others. This means I have to catch them. I was not looking forward to this task. Although hardly studied, these jays are regarded as having a very high level of intelligence. In fact in terms of their brain to body size ratio (a common way of assessing intelligence) Plush-crested jays are on par with great apes. This is why I wasn’t looking forward to trying to catch them. Nevertheless I though I would give it a go. With help from volunteers Jaime and Claire, and intern Aimme, we set up two mist nets in areas I regularly see the jays fly through. Then I played a series of vocalisations to attempt to attract them over. It certainly got their attention as 6 individuals turns up but, unfortunately, they did not take the bait and fly into the nets. Instead they proceeded to tease me for a couple of hours. Flying low and close to the net they would dip up or down at the last second to miss getting caught. Now I will probably have to switch to baiting cages where the door shuts when the bird pecks at the bait. Lets see how much success I have with that.
I have also started to try and cultivate some maggots. Not a nice job but I need them for the feeding stations. One of results that have come from the study thus far is that they are primarily insectivores. This may explain why they were not interested in my potato peelings. The battle of wits between man and jay continue.


Social and ecological factors among Clyomys laticeps (broad-headed spiny rat).

Initial results are in on the bush we suspect may be important to Clyomys. I have excavated 5 root samples from 5 of these bushes. As soon as I had the roots out they were put into sealable plastic bags. This was to prevent all the moisture from escaping. Once back at camp I weighed all the samples to get the weight of them when they are still holding water. Then I placed all the samples on a baking tray and put them in the oven on a low heat. I left them for 3 days so that all of the moisture would be taken out of the roots. After the drying period was finished I weighed all of them again to see what the differences was and to calculate what percentage of the roots are made up from water. Now, although the percentage of water in these roots was high – 49% - they contained only 2% more water than two other species I also tested. This means we need to look at other variables to try and work out what it is that is attracting Clyomys. So if we can reject our hypothesis that it is water content that attracts clyomys we will then start looking at nutrient levels.

Until next time I'll say goodbye.

Best Wishes,

Luke

domingo, 10 de julio de 2011

A new large mammal, a new lizard and a snake without a rattle in its tail!

Well I was going to start this post with after the excitement of my butterflies hatching things have been pretty quite here, however that was until yesterday morning!

You are not going to believe what I saw. I’m still reeling from the shock myself. 7am, walking along the beach, minding my own business and what should swim past me, casual as you like…? Only a capybara!!! It was just paddling along as calm as can be, diving and surfacing without a care in the world. And it was MASSIVE! It’s no wonder they are the worlds largest rodent it was HUGE! Not only was it amazing for me to see, as I have never seen one before, but it is the first sighting here at Laguna Blanca which means another large mammal species for our records. This place is incredible!

That’s not the only amazing thing to have happened in the last 24 hours. I recently caught a couple of lizards in one of my pitfall traps which look similar to a species we catch quite regularly here, Cercosaura schreibersii, but when I compared them there was something that just didn’t look right. And after much conflabbing and emailing of photos with Paul our scientific co-ordinator it turns out that they are different. They are in fact a species of which there is only one record of in Paraguay and that was from 1895 !! Another really important find at Laguna Blanca!

Other than all of that though, it has to be admitted its’ been pretty quiet. This is due to it being so cold all of my reptile and amphibian friends have been tucked up in their beds and refusing to come out. All except for the Bothrops – a highly venomous snake that doesn’t rattle to warn you its there - that Aimee one of our interns keeps running into on her small mammal transects. However it always manages to disappear whenever I am available to go and remove it! I am on call now, whenever she is in the field I am prepped and ready to drop everything and nab it. I fear its going to be a long wait!

That’s all folks

See you next time

Helen