Автор: Guys transmitted once the estimated 53,000 kcal in order to egg while in the incubation, the same as 5 kilogram out-of lipids (up to 18–20% of the body weight). Those viewpoints are most likely a little overestimate of your own energy called for to possess incubation as we thought you to definitely incubation initiate at the time one and all of eggs is actually laid at the same time and tend to be similarly covered by a man (aforementioned presumption is in fact violated during the high handbags). As rhea males barely hop out brand new nest to pass through, the imagine brings a keen approximation of your web productive cost of incubation. This new estimated productive pricing having rheas is a lot like that mentioned in Emus (Dromaius novaehollandiae), a different sort of ratite varieties where in fact the men really works all of the incubation. Male Emus forgotten seven kg (regarding 17–20% of their pounds) throughout the 56 times of incubation ( Dawson ainsi que al. 1984). Likewise, Brown Kiwi (Apteryx australis) males forgotten ?23% of their fat while in the 91 days of incubation, in the event where types incubation try partly distributed to female ( Taborsky and Brugger 1994). This new effective financial support in adult care just after hatching is much more difficult in order to imagine. However, the lower percentage of date used on serving by the men that have chicks provides a relative estimate of your price of hottie care. Because the proper care of chicks continues until he or she is cuatro–6 months old, that costs will be more important than previously heading.
All of our show indicate that Higher Rhea guys want high quantities of effective supplies to begin with a breeding shot. You to energetic consult could describe why Fernandez and you can Reboreda 1998) that will additionally be accountable for the new high rate of early nest desertion that we seen ( Fernandez and you may Reboreda 2000). Variations in men condition might like polygyny in the event the female favor so you can partner which have guys having enough pounds supplies, as happens in most other precocial types where guys incubate ( Petrie 1983). An alternative cause on the amount regarding polyandry and you will polygyny during the Greater Rheas is that the price of eggs creation constrains the latest number of women that can set eggs. Queen (1973) projected you to definitely to have galliforms, each and every day limit cost of egg design is 21–30% of everyday time intake. Although cousin egg size in the ratites (with the exception of kiwis) is gloomier than in other communities ( Clutton-Brock 1991), egg installing would want new capital from ?50% of one’s energy spent by male throughout the incubation in a smaller several months (everything 10–15 days). When the lady was in fact restricted from the number of eggs they may be able lay, they need to get a hold of top quality guys and you may, thus, only a few males might have an opportunity to have mating.
The newest high-energy requirement may possibly affect the the total amount from polyandry given that a reduced proportion of men inside the adequate health may lead to a woman-biased operational sex ratio, that will like polygyny
According to you to definitely creator, the expense of nest safeguards for ladies (a decrease in producing eggs) might possibly be mail order bride real stories higher than the expense of chance for guys (extra matings). Ergo, ladies cannot offer after that adult care shortly after installing and really should produce most eggs, whereas males would be to suppose new adult commitments. Thus, uniparental male worry possess advanced as a result of the necessity of very early nest attendance crucial for egg otherwise colony success.
Ligon (1993, 1999) features proposed that very first particular parental care into the birds try defense off egg from predators
Our very own rhea research, as well as that from Ostriches, was in line with you to theory. Ostriches keeps large pricing regarding eggs and you may nest predation during putting ( Bertram 1992), and you may egg from inside the untreated nests is arrive at fatal temperature ( Bertram and you will Burger 1981). Highest egg heat during the unattended nests is likewise critical for almost every other ratites, such as for example Emus, that have black egg (contrary to rheas and you will Ostriches with white egg).
