We discover 105 effective nests, primarily while you are operating more sluggish across the surroundings
During for every breeding seasons we wanted nests intensively around the analysis site. I observed brand new destiny each and every colony through to the egg hatched or even the nest were not successful. Nests was indeed went along to between 0900 and 1700 times plus the check outs survived 2 hundred meters off the nest, anywhere between 1000 and you may 1700 circumstances. Length of new focal observations varied out of 31 min to eight h, plus the total duration of observation are 30.5 h. Due to the fact the observations varied in total and there have been times into the that the male was at the new colony right through the day, so you’re able to imagine this new part of colony focus we pooled the latest focal findings regarding nests which were at the same stage of incubation.
Just like the guys are more likely to wasteland the nest when disrupted from the an initial phase of one’s nesting cycle ( Fernandez and you will Reboreda 2000), we monitored a lot of nests (9 of one’s eleven times totaling 34 colony-days) throughout the middle- or later incubation
The thermistor of the temperature logger was introduced in a fresh natural orphan egg (unattended eggs laid far from active nests; Navarro et al. 1998) through a small hole in the equatorial plane and fixed to the eggshell with epoxy adhesive. The egg was attached to the center of the nest and the data logger was hidden under the nest. The data logger automatically recorded the temperature at 3.8 or 6 min intervals during four or six days, respectively. We monitored egg temperatures in those 11 nests totaling 40 nest-days. In the other two cases we started the monitoring of the nest three and five days after the laying of the first egg. None of the nests used for monitoring male activity was deserted. We used the decrease in egg temperature to determine when the male left the nest ( Hainsworth et al. 1998, Flint and Grand 1999). We previously estimated egg cooling-rate of Greater Rhea eggs by heating six fresh eggs up to 33°C and then placing them in an environment at a temperature of 25°C, similar to temperatures registered in our study area between 1100 and 1300 hours (the warmest time of the day). We estimated egg cooling-rate by dividing the initial difference in temperature between eggs and the environment by the time elapsed until eggs reached a thermal equilibrium with the environment. The estimated egg cooling-rate for a temperature gradient of 8°C was 0.063 ± 0.01°C min ?1 . We assumed that the male left the nest when the difference in egg temperature was |T(t) ? T(t?1)| > 1°C, where T(t) and T(t?1) are egg temperatures at a time interval of 15 min when data loggers were set at 3.8 min intervals or 18 min when they were set at 6 min intervals. We considered that the male was outside the nest since the time at which the difference between T(t) and T(t?1) was negative until the time it was positive (i.e. the male resumed incubation). Although the sun can heat eggs when the male is absent (particularly at midday), unattended eggs never reached temperatures >30°C (see below). Therefore, it was possible for us to discriminate between an er postordrebruder ulovlige increase in temperature produced by the Sun and one produced by males when they resume incubation.
We as well as mentioned variation from inside the eggs heat in three fresh nests (nests versus male notice). I made use of nests that were previously left behind given that experimental nests. Inside for every colony (clutch systems regarding 16, 21, and you can 23 eggs) we repaired one-egg with a beneficial thermistor inside, on the center of your own nest similarly one i performed into the productive nests (select a lot more than).