It is fundamentally approved the positioning, attendance, and shelter of one’s colony could be the head activities you to dictate the new viability out-of eggs in addition to rates out-of colony predation ( Arnold et al. 1987, Martin 1995, Cresswell 1997). Constancy while in the incubation will bring a great thermal environment with the advancement of embryos and protects eggs regarding significant temperatures that could apply at their hatchability ( Give 1982). For the variety where just one sex incubates, you will find a trade-away from between attendance and you may coverage of the colony and repairs from a good opportunity balance ( Thompson and you will Ravelin 1987, Flint and you may Huge 1999). On top of that, nest appeal can also be reduce steadily the likelihood of eggs predation often from the effective nest safety or down seriously to a reduction of brand new incubation age eggs, which a reduced amount of go out they are exposed to predators ( Clutton-Brock 1991, Creswell 1997, Flint and Huge 1999).
Methods
Within the Better Rheas (Rhea americana), adult care is completed only of the men, having ladies limiting the money on creation and you will laying out of egg. Rhea guys generate brand new colony, incubate this new egg, and look after the chicks immediately after hatching ( Muniz 1885, Bruning 1974, Fernandez and you may Reboreda 1998). Where kinds, this new mating program combines harem polygyny and you may sequential polyandry ( Muniz 1885, Bruning 1974). At the beginning of the brand new breeding 12 months (August–September) males contend getting, and you can protect a team otherwise harem of 5 to help you 7 people. A man copulates on ladies at least one time all of the two to three weeks. Lady place egg most of the 48 h to have 10–several weeks inside a communal colony ( Bruning 1974, Fernandez and you will Reboreda 1998). Chicks hatch synchronously as well as their proper care is completed entirely by men ( Bruning 1974, Fernandez and you may Reboreda 1998). After the people Vietnamesisk kone ordre finish the installing into earliest male they can also be copulate and you will set eggs for another male ( Muniz 1885, Bruning 1974).
Right here, we analyzed brand new the amount out-of Greater Rhea men adult care throughout the eggs and you may chick levels. We counted nest desire of the men and its effect on the newest viability and you will emergency off eggs. We tested if men absences inside the incubation were timed so you can stop embryos getting fatal heat through the development, or to slow down the danger of eggs predation. We analyzed the outcome off colony attention for the stability out of the new eggs by the contrasting heat from eggs during the day in the nests with and you may in place of male appeal. Furthermore, we evaluated effect of male worry to your likelihood of eggs predation by the researching the fresh endurance regarding egg for the nests which have and you may instead of male care. Additionally, i examined the extent out-of parental care just after hatching and you may evaluated their relative pricing by the comparing enough time used on feeding and vigilance from the males that have chicks, nonreproductive single males and guys for the nonreproductive organizations.
Study urban area
The research is actually used inside the reproduction (August–January) and you may nonbreeding (January–July) year off 1993–1997, in 2 spatially contiguous cows plantations regarding step three,five-hundred and 800 ha. Those individuals ranches was basically receive near the town of Standard Lavalle inside this new state out of Buenos Aires, Argentina (36°25’S, 56°56’W). A population off ?400 rheas is actually handled thereon research area, with a great sex ratio biased somewhat with the men (55% males and you can 45% females). The analysis city is actually a moderate grassland included in the therefore-called flooding pampa ( Soriano 1991). The bedroom is flat, low, and you will marshy, with little to no of your own homes ascending >ten m above sea level. Native flowers comes with quick grass kinds that have strewn patches regarding woodland regarding higher components. One to city is utilized nearly simply for cattle husbandry whilst still being keeps a number of insane communities from Higher Rheas. Within research site, mature rheas don’t possess absolute predators right now (i.elizabeth. cougars [Felis concolor]) but Crested Caracara (Polyborus plancus), Chimango Caracara (Milvago chimango), gray foxes (Dusicyon gymnocercus), grisons (Galictis sp.), and you may opossums (Didelphis albiventris) prey heavily towards rhea chicks. Almost every other non-local predators which could assault each other adults and you will chicks is feral pet (M. Beade pers. obs.) but we have zero evidence you to that kind of predation got happened inside investigation period.