We found 105 energetic nests, primarily whenever you are operating much slower across the surroundings
Through the for each and every breeding year i sought after nests intensively around the analysis webpages. I accompanied new future of every nest before egg hatched and/or colony were unsuccessful. Nests were visited between 0900 and you can 1700 days in addition to visits live two hundred m from the nest, anywhere between 1000 and you can 1700 period. Amount of the focal observations varied out of 30 min so you can seven h, as well as the full lifetime of observation is actually 31.5 h. While the our findings varied in length so there was indeed instances in that the men is at this new colony from day to night, so you can imagine this new portion of colony appeal i pooled new focal observations of nests that have been at the same phase regarding incubation.
Given that guys are more inclined to desert the fresh new colony when interrupted during the an initial phase of your own nesting years ( Fernandez and you may Reboreda 2000), we monitored the vast majority of nests (9 of your own 11 times totaling 34 colony-days) during the mid- 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 Japansk brud 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 increase in temperature produced by the Sun and one produced by males when they resume incubation.
I as well as measured adaptation within the eggs heat for the around three fresh nests (nests versus men attract). I utilized nests that were in earlier times deserted just like the experimental nests. During the for each nest (clutch brands regarding 16, 21, and you will 23 egg) we fixed one-egg which have a great thermistor into the, on the heart of the nest similarly one to i did for the productive nests (look for significantly more than).