It’s fundamentally accepted the position, attendance, and you can protection of your own colony will be main points one to dictate the new viability away from eggs while the price out of nest predation ( Arnold et al. 1987, Martin 1995, Cresswell 1997). Constancy during the incubation will bring a favorable thermal ecosystem on innovation out of embryos and you will covers egg of high temperatures that may connect with the hatchability ( Give 1982). Within the types where one sex incubates, there is certainly a trade-regarding between attendance and you may coverage of your own nest and maintenance out of a good time harmony ( Thompson and you will Ravelin 1987, Flint and Grand 1999). Concurrently, nest interest is reduce steadily the chance of eggs predation often because of the energetic nest protection or right down to a reduced amount of the brand new incubation ages of egg, and this a decrease in time he’s confronted with predators ( Clutton-Brock 1991, Creswell 1997, Flint and you will Grand 1999).
Procedures
Within the Higher Rheas (Rhea americana), adult worry is accomplished entirely by the men, having people limiting the investment on development and you will laying of egg. Rhea guys build the new colony, incubate the fresh eggs, and you will look after the chicks once hatching ( Muniz 1885, Bruning 1974, Fernandez and you will Reboreda 1998). Where varieties, the latest mating program brings together harem polygyny and you may sequential polyandry ( Muniz 1885, Bruning 1974). At the beginning of the newest reproduction 12 months (August–September) men compete getting, and you will protect a group otherwise harem of five to help you 7 females. The male copulates toward lady one or more times all a couple to 3 months. Ladies place egg the forty eight h to have 10–several weeks into the a communal colony ( Bruning 1974, Fernandez and you can Reboreda 1998). Chicks hatch synchronously and their care is completed exclusively of the men ( Bruning 1974, Fernandez and Reboreda 1998). Pursuing the ladies finish the laying for the basic men they is also copulate and you can lay egg for the next men ( Muniz 1885, Bruning 1974).
Right here, we evaluated this new extent away from Greater Rhea men adult proper care through the eggs and you can hottie amounts. We mentioned nest focus by the men and its own influence on the newest viability and you can endurance out-of egg. I looked at if men absences inside incubation was timed to help you avoid embryos interacting with deadly temperature throughout advancement, or even slow down the likelihood of egg predation. We analyzed the result out of colony desire towards the viability out of the eggs from the evaluating temperatures out-of eggs throughout the day in nests having and you may without men attract. Likewise, i evaluated aftereffect of male worry towards the likelihood of eggs predation because of the researching the fresh new emergency out-of egg when you look at the nests which have and instead of male proper care. As well, i reviewed the latest the quantity of adult care and attention once hatching and you will evaluated the relative pricing of the evaluating the full time allocated to serving and you can vigilance because of the guys that have chicks, nonreproductive solitary males and men during the nonreproductive teams.
Study urban area
The research try used from inside the breeding (August–January) and you can nonbreeding (January–July) seasons out of 1993–1997, in 2 spatially contiguous cows ranches of step 3,500 and you may 800 ha. Those plantations was in fact receive close to the city of General Lavalle inside the the brand new province out-of Buenos Aires, Argentina (36°25’S, 56°56’W). A society away from ?eight hundred rheas is maintained on that investigation town, which have an excellent sex ratio biased a bit on men (55% males and you will forty five% females). The analysis area try a temperate grassland included in the very-entitled ton pampa ( Soriano 1991). The space is flat, lowest, and you will marshy, with little of your house lovingwomen.org bunu buradan Г¶Дџrenin ascending >ten m above sea-level. Native flowers is made of quick grass species with thrown spots from forest throughout the high section. One to urban area can be used nearly exclusively for cattle husbandry nonetheless enjoys a few crazy communities out-of Greater Rheas. Within our analysis website, mature rheas don’t possess absolute predators currently (we.age. cougars [Felis concolor]) however, Crested Caracara (Polyborus plancus), Chimango Caracara (Milvago chimango), gray foxes (Dusicyon gymnocercus), grisons (Galictis sp.), and you can opossums (Didelphis albiventris) sufferer greatly to your rhea chicks. Almost every other low-indigenous predators which will assault both grownups and you may chicks is actually feral animals (Yards. Beade pers. obs.) however, you will find no facts you to that sort of predation had happened inside study months.
