We located 105 productive nests, mostly while you are operating much slower across the surroundings
During the for each breeding year we sought out nests intensively everywhere the research website. We then followed the destiny of each nest till the egg hatched or the nest were not successful. Nests were went along to ranging from 0900 and you may 1700 hours additionally the visits survived 2 hundred m away from the colony, between 1000 and you may 1700 times. Period of the fresh new focal findings varied from 30 min in order to seven h, while the overall duration of observation are 31.5 h. Given that our very own observations varied long there were cases in the which the male was at brand new nest all the time, to help you estimate this new part of nest attention we pooled the new focal findings of nests that were at the same stage out of incubation.
Since men will desert the nest when disrupted within an early stage of your own nesting period ( Fernandez and Reboreda 2000), we monitored a lot of the nests (nine of your 11 cases totaling 34 colony-days) during the middle- otherwise late 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 Kilde 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 increase in temperature produced by the Sun and one produced by males when they resume incubation.
We also mentioned adaptation within the eggs temperatures for the around three fresh nests (nests versus male notice). I put nests that had been in the past left behind because fresh nests. For the for each and every nest (clutch brands of sixteen, 21, and you can 23 eggs) we fixed one egg with an effective thermistor into the, on the cardio of one’s nest in a similar way that i performed to your energetic nests (discover above).