It is generally approved the positioning, attendance, and you will safeguards of the colony may be the chief activities you to definitely influence this new stability regarding egg plus the rates away from colony predation ( Arnold ainsi que al. 1987, Martin 1995, Cresswell 1997). Constancy while in the incubation provides a good thermal ecosystem to the development of embryos and you can protects egg out of tall temperature which could apply to the hatchability ( Offer 1982). For the varieties where just one sex incubates, there’s a swap-out of anywhere between attendance and security of your own nest and you will restoration away from a good times balance ( Thompson and you may Ravelin 1987, Flint and you can Grand 1999). On top of that, colony attract can decrease the risk of eggs predation possibly from the active nest Korece kadД±n vs AmerikalД± kadД±n cover otherwise down seriously to a reduced total of the newest incubation age of eggs, and this a reduced amount of day he is confronted by predators ( Clutton-Brock 1991, Creswell 1997, Flint and Huge 1999).

Strategies

In the Deeper Rheas (Rhea americana), parental care is carried out only of the men, having ladies limiting the funding for the manufacturing and installing from egg. Rhea guys generate new colony, incubate the brand new egg, and you may care for the chicks just after hatching ( Muniz 1885, Bruning 1974, Fernandez and Reboreda 1998). Because kinds, brand new mating system brings together harem polygyny and you can sequential polyandry ( Muniz 1885, Bruning 1974). Early in the new breeding 12 months (August–September) males compete to have, and you can protect a team or harem of five to eight females. A man copulates for the women one or more times all the a few to three weeks. Females lay eggs the 48 h for 10–12 days during the a communal colony ( Bruning 1974, Fernandez and Reboreda 1998). Chicks hatch synchronously and their care and attention is completed only from the men ( Bruning 1974, Fernandez and you may Reboreda 1998). Following the females finish the putting toward earliest men they normally copulate and you will put egg for the next men ( Muniz 1885, Bruning 1974).

Here, i evaluated this new the quantity regarding Greater Rhea men adult care and attention throughout the eggs and you will chick degree. We counted nest attract by men and its own affect new stability and you can success regarding eggs. I checked-out whether male absences when you look at the incubation had been timed to help you avoid embryos getting together with deadly heat while in the invention, or perhaps to slow down the threat of egg predation. I examined the end result away from colony attract towards the viability out-of the brand new eggs by the comparing temperature from eggs during the day inside nests that have and versus men attract. Furthermore, we examined effectation of men care with the odds of egg predation because of the comparing the brand new success of eggs within the nests that have and you will as opposed to men care and attention. As well, we assessed new the total amount from parental worry after hatching and you may evaluated their cousin rates from the contrasting the time spent on feeding and you will vigilance by the men having chicks, nonreproductive solitary males and guys inside nonreproductive groups.

Data town

The research try conducted during the breeding (August–January) and you can nonbreeding (January–July) seasons from 1993–1997, in 2 spatially contiguous cattle ranches regarding step three,five hundred and you may 800 ha. Those ranches have been found around the city of General Lavalle in the state regarding Buenos Aires, Argentina (36°25’S, 56°56’W). A society regarding ?400 rheas is actually handled on that research city, which have a beneficial sex ratio biased a bit to your guys (55% males and forty five% females). The analysis town are a temperate grassland within the therefore-entitled flood pampa ( Soriano 1991). The bedroom was flat, lower, and you can marshy, with little to no of your homes ascending >ten meters a lot more than sea-level. Indigenous vegetation comprises of brief yard kinds having scattered patches away from woodland regarding the high areas. One to city is utilized nearly simply for cows husbandry but still has actually several crazy populations from Greater Rheas. Within our analysis webpages, mature rheas don’t have natural predators right now (we.age. cougars [Felis concolor]) however, Crested Caracara (Polyborus plancus), Chimango Caracara (Milvago chimango), grey foxes (Dusicyon gymnocercus), grisons (Galictis sp.), and opossums (Didelphis albiventris) prey greatly into the rhea chicks. Other low-local predators which will attack each other grownups and you will chicks was feral pet (Yards. Beade pers. obs.) however, i’ve zero evidence one to that kind of predation got took place for the research months.