Males transmitted as estimated 53,000 kcal in order to eggs throughout the incubation, roughly the same as 5 kilogram of lipids (just as much as 18–20% of their fat). Those people thinking are likely a small overestimate of one’s time necessary having incubation because we assumed one incubation initiate on day one to and all egg was applied at the same time and so are equally covered by the male (the second assumption is really violated when you look at the highest handbags). Since rhea males scarcely log off the fresh new colony to pass through, the guess will bring an enthusiastic approximation of web active price of incubation. The brand new projected energetic prices to own rheas is much like that measured into the Emus (Dromaius novaehollandiae), a different ratite types where in fact the men really works all the incubation. Men Emus missing seven kg (from the 17–20% of their fat) throughout 56 days of incubation ( Dawson ainsi que al. 1984). Similarly, Brown Kiwi (Apteryx australis) men destroyed ?23% of their body weight throughout 91 days of incubation, even in the event in that varieties incubation are partly shared with people ( Taborsky and you may Brugger 1994). This new effective money when you look at the parental proper care just after hatching is far more difficult so you can imagine. However, the reduced portion of big date allocated to eating because of the males having chicks will bring a close relative estimate of the price of chick worry. Given that proper care of chicks lasts up to he or she is 4–half a year old, you to definitely prices will be more significant than previously going.
All of our efficiency imply that Better Rhea males require high levels of effective reserves to begin with a breeding try. One to effective consult you will definitely determine as to the reasons Fernandez and you will Reboreda 1998) and may even also be responsible for this new high rate regarding early colony desertion that individuals noticed ( Fernandez and you can Reboreda 2000). Variations in male standing could also choose polygyny if people choose so you’re able to partner with guys with sufficient body weight supplies, while the happens in other precocial species in which guys incubate ( Petrie 1983). A choice cause with the extent regarding polyandry and you may polygyny inside the Better Rheas is the fact that the price of egg creation constrains the new amount of females that lay eggs. Queen (1973) estimated one for galliforms, every day limitation price of egg production is 21–30% regarding everyday time intake. Even though relative eggs size when you look at the ratites (except for kiwis) is leaner than in other organizations ( Clutton-Brock 1991), eggs laying would need the latest financial support of ?50% of one’s opportunity invested from the male through the incubation but in a shorter several months (around ten–15 days). In the event the female have been restricted on quantity of eggs they’re able to lay, they want to pick quality men and you can, thus, not all guys would have a chance getting mating.
The brand new high-energy specifications may also impact the extent out-of polyandry given that a low proportion of males inside sufficient health can get bring about a lady-biased working sex ratio, that can choose polygyny
Predicated on you to definitely blogger, the cost of colony safety for women (a decrease in producing egg) will be greater than the cost of window of opportunity for men (a lot more matings). Hence, female cannot give then adult worry just after laying and may make most egg, whereas males should assume the brand new parental requirements. Ergo, uniparental male worry could have advanced because of the necessity of early colony attendance critical for eggs otherwise nest en iyi Rusya tanД±Еџma siteleri survival.
Ligon (1993, 1999) possess proposed that initial kind of parental care and attention when you look at the birds try shelter from egg out of predators
The rhea study, after that out of Ostriches, try consistent with you to definitely theory. Ostriches features higher cost away from egg and you can colony predation during laying ( Bertram 1992), and you may eggs in untreated nests is reach life-threatening heat ( Bertram and Hamburger 1981). Highest egg heat in the unattended nests is likewise crucial for almost every other ratites, such as Emus, with black eggs (as opposed to rheas and Ostriches with light eggs).