Recently it has been discovered that Black Larks, living on the Eurasian steppes in Kazakhstan, transport dung to their nests to build large 'pavements' . Weird and almost dirty behaviour, but what is the use of it? This spring a team of researchers from the Universities of Wageningen and M√ľnster and the Association for the Conservation of Biodiversity in Kazakhstan (ACBK) will try to answer this question, doing fieldwork in the Korgalzhyn area in Kazakhstan. On this blog we will post on our findings and adventures.

Friday, 26 April 2013

Few days to go - equipment modifications


All is set! Equipment is ready, the visas have been arranged and within a week we'll be searching for Black Lark nests in Korgalzhyn, Kazakhstan. Johannes leaves a bit earlier and will meet Ruslan and Gera in Astana on Saturday. Thijs and Thomas will follow on Monday.

We did some interesting modifications on the equipment. The Ibutton temperature loggers we use to investigate incubation patterns and a possible isolating effect of dung are tiny (about the size of a penny or a 5-cent-piece, 16 mm) and very light. No chance that we would find them again in the steppe if the bird decided to remove it, and why wouldn't they. The larks for sure are capable to remove it, as carrying pieces of horse dung is not a problem for them! Digging into the literature we found some clever ideas to overcome this problem. What we now did (at least for one temperature logger for the moment) is to attach Velcro to the top of the button and to the top of a 16 cm long nail. We will push the nail into the soil beneath the nest, so that only the button sticks out. For sure the larks will not remove it now, at least that's what we hope. By using Velcro we can easily detach the buttons to be able to read them more easy.


Ibutton temperature logger with velcro



They fit snugly to this nail!

We were wondering if the metal of the nail had an influence on temperature measurements, so we tested temperature logging with loggers mounted on nails versus loggers put on the soil. There seems to be a small temperature buffer effect of the velcro/nail combination when compared to loose Ibuttons, i.e. temperatures were approximately 0.5 degrees higher when using our construction. So we decided to mount all Ibuttons on nails, also those that are used outside nests. In this way the buffering applies to all Ibuttons and won't cause any problems in comparative analyses.


The green and blue lines (which largely overlap) are temperature curves from loose Ibuttons
put on the ground, the red and purple lines (also a large overlap) of Ibuttons attached to nails
 with velcro. As you can see, the temperature logged by Ibuttons on a nail is about 1° celcius higher,
a little more than the variation expected in these Ibuttons (half a degree).

For our planned experiment that looks into whether dung helps to avoid nest trampling by cattle, we would need to use an aweful lot of eggs! Using chicken eggs might be a good idea, but this is very wasteful. That's why we decided to try something with small (water) balloons and papier-mache. Easy to make, low costs, and no eggs are harmed in the process. Here the first try-out: They are pretty solid but still easy to "trample". Now we only need to make sure they are not blown away by the wind! We also discussed using plasticine eggs, since this material is heavier and can be molded / re-used more easily. It does increase the costs, so we might stick with the idea of using papier-mache eggs.

The papier-mache eggs before...
...and after a herd of students passed trough!

Using small wooden sticks to pin the "eggs" into the soil so they are not blown away.

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