It’s generally recognized that the location, attendance, and defense of colony are definitely the main affairs you to definitely dictate this new viability of egg while the rates out of nest predation ( Arnold mais aussi al. 1987, Martin 1995, Cresswell 1997). Constancy throughout the incubation brings a good thermal environment toward advancement off embryos and you can protects eggs out-of significant temperature which will apply at their hatchability ( Offer 1982). When you look at the types in which one sex incubates, there is a trade-of ranging from attendance and you will safety of your nest and you can restoration regarding a great opportunity harmony ( Thompson and you may Ravelin 1987, Flint and you may Huge 1999). Additionally, colony appeal can reduce the danger of eggs predation often from the productive nest security otherwise right down to a reduced amount of the latest incubation age of eggs, and therefore a reduction of date he’s confronted with predators ( Clutton-Brock 1991, Creswell 1997, Flint and you may Grand 1999).

Measures

Into the Greater Rheas (Rhea americana), parental proper care is carried out entirely of the guys, that have ladies limiting their money towards creation and you may putting out-of eggs. Rhea guys create the newest colony, incubate the fresh new eggs, and look after the chicks once hatching ( Muniz 1885, Bruning 1974, Fernandez and you may Reboreda 1998). Because species, brand new mating program integrates harem polygyny and you may sequential polyandry ( Muniz 1885, Bruning 1974). Early in this new reproduction seasons (August–September) males vie getting, and you can guard a team otherwise harem of 5 to seven females. A man copulates for the ladies at least one time all a few to 3 days. Lady set egg the forty eight h having ten–12 days into the a public nest ( Bruning 1974, Fernandez and you can Reboreda 1998). Chicks hatch synchronously as well as their care is done entirely because of the male ( Bruning 1974, Fernandez and you can Reboreda 1998). After the females finish the installing towards first men it can copulate and you can lay eggs for the next men ( Muniz 1885, Bruning 1974).

Here, we evaluated brand new extent away from Greater Rhea men adult care and attention through the eggs and you will chick levels. I mentioned colony attention of the men and its particular affect brand new stability and emergency out of egg. We looked at if male absences inside incubation was in fact timed so you can end embryos reaching lethal heat during development, or perhaps to slow down the Almanca kadД±n bul risk of eggs predation. We examined the outcome away from colony appeal on stability out of the new egg by comparing temperature away from eggs throughout the day from inside the nests which have and you may instead of male attract. Furthermore, i analyzed effectation of male care and attention to the odds of egg predation by researching the new success out of eggs for the nests that have and instead male proper care. Simultaneously, i examined the fresh the total amount regarding parental care and attention shortly after hatching and you may examined the relative prices because of the contrasting committed allocated to giving and you can vigilance by males having chicks, nonreproductive unmarried guys and guys into the nonreproductive organizations.

Investigation urban area

The analysis was held into the reproduction (August–January) and nonbreeding (January–July) season out-of 1993–1997, in two spatially contiguous cattle plantations out of step 3,500 and you will 800 ha. Those people plantations was indeed discovered close to the city of Standard Lavalle within the the new province of Buenos Aires, Argentina (36°25’S, 56°56’W). A society away from ?400 rheas was handled thereon study urban area, which have an effective sex ratio biased a little on males (55% males and you may forty-five% females). The research town was a moderate grassland within the very-named flooding pampa ( Soriano 1991). The bedroom are flat, lowest, and marshy, with little to no of your homes ascending >10 meters more than sea level. Indigenous flowers comes with brief grass kinds with thrown patches of forest on high components. One city can be used nearly exclusively for cattle husbandry nonetheless has actually a few nuts populations of Deeper Rheas. Within our analysis webpages, mature rheas lack natural predators at the moment (we.elizabeth. cougars [Felis concolor]) however, Crested Caracara (Polyborus plancus), Chimango Caracara (Milvago chimango), grey foxes (Dusicyon gymnocercus), grisons (Galictis sp.), and you may opossums (Didelphis albiventris) prey heavily to the rhea chicks. Almost every other non-indigenous predators which will attack each other grownups and you may chicks is actually feral pet (M. Beade pers. obs.) however, i’ve zero research you to that kind of predation got taken place within the investigation months.