Editing Moa (section)

===Reproduction===
[[File:Emeus egg and embryo.jpg|thumb|left|An egg and embryo fragments of ''Emeus crassus'']]
The pairs of species of moa described as ''Euryapteryx curtus'' / ''E.&nbsp;exilis'', ''Emeus huttonii'' / ''E.&nbsp;crassus'', and ''Pachyornis septentrionalis'' / ''P.&nbsp;mappini'' have long been suggested to constitute males and females, respectively. This has been confirmed by analysis for sex-specific genetic markers of DNA extracted from bone material.<ref name="Huynen" />

For example, before 2003, three species of ''Dinornis'' were recognised: South Island giant moa (''D.&nbsp;robustus''), North Island giant moa (''D.&nbsp;novaezealandiae''), and slender moa (''D.&nbsp;struthioides''). However, DNA showed that all ''D.&nbsp;struthioides'' were males, and all ''D.&nbsp;robustus'' were females. Therefore, the three species of ''Dinornis'' were reclassified as two species, one each formerly occurring on New Zealand's North Island (''D.&nbsp;novaezealandiae'') and South Island (''D.&nbsp;robustus'');<ref name="Huynen" /><ref>{{Cite journal |last1=Bunce |first1=M. |last2=Worthy |first2=Trevor |author2-link=Trevor Worthy |last3=Ford |first3=T. |last4=Hoppitt |first4=W. |last5=Willerslev |first5=E. |last6=Drummond |first6=A. |last7=Cooper |first7=A. |url=https://www.cs.auckland.ac.nz/~alexei/2003_Bunce_etal.pdf |archive-url=https://web.archive.org/web/20190128092134/https://www.cs.auckland.ac.nz/~alexei/2003_Bunce_etal.pdf |url-status=dead |archive-date=28 January 2019 |title=Extreme reversed sexual size dimorphism in the extinct New Zealand moa Dinornis |journal=Nature |volume=425 |issue=6954 |pages=172–175 |year=2003 |pmid=12968178 |doi=10.1038/nature01871 |bibcode=2003Natur.425..172B|s2cid=1515413 }}</ref> ''D.&nbsp;robustus'' however, comprises three distinct genetic lineages and may eventually be classified as many species, as discussed above.

Examination of growth rings in moa cortical bone has revealed that these birds were [[k-selection|K-selected]], as are many other large endemic New Zealand birds.<ref name="Turvey" /> They are characterised by having a low [[fecundity]] and a long [[wikt:maturation|maturation]] period, taking about 10 years to reach adult size. The large ''Dinornis'' species took as long to reach adult size as small moa species, and as a result, had fast skeletal growth during their juvenile years.<ref name="Turvey" />

No evidence has been found to suggest that moa were colonial nesters. Moa nesting is often inferred from accumulations of eggshell fragments in [[caves]] and rock shelters, little evidence exists of the [[bird nest|nest]]s themselves. Excavations of rock shelters in the eastern North Island during the 1940s found moa nests, which were described as "small depressions obviously scratched out in the soft dry [[pumice]]".<ref>Hartree (1999)</ref> Moa nesting material has also been recovered from rock shelters in the Central Otago region of the South Island, where the dry climate has preserved plant material used to build the nesting platform (including twigs clipped by moa bills).<ref name="Wood">Wood, J.R. (2008)</ref> [[Seed]]s and [[pollen]] within moa coprolites found among the nesting material provide evidence that the nesting season was late spring to summer.<ref name="Wood" />

Fragments of moa eggshell are often found in [[archaeological]] sites and [[sand dunes]] around the New Zealand coast. Thirty-six whole moa eggs exist in museum collections and vary greatly in size (from {{convert|120|-|240|mm|in}} in length and {{convert|91|-|178|mm|in}} wide).<ref>Gill, B.J. (2007)</ref> The outer surface of moa eggshell is characterised by small, slit-shaped pores. The eggs of most moa species were white, although those of the upland moa (''Megalapteryx didinus'') were blue-green.<ref name="Huynen, Leon 2010">Huynen, Leon; Gill, Brian J.; Millar, Craig D.; and Lambert, David M. (2010)</ref>
[[File:The skeleton of female upland moa.JPG|thumb|The skeleton of female upland moa with egg in unlaid position within the pelvic cavity in Otago Museum]]
A 2010 study by Huynen et al. found that the eggs of certain species were fragile, only around a millimetre in shell thickness: "Unexpectedly, several thin-shelled eggs were also shown to belong to the heaviest moa of the genera ''Dinornis'', ''Euryapteryx'', and ''Emeus'', making these, to our knowledge, the most fragile of all avian eggs measured to date. Moreover, sex-specific DNA recovered from the outer surfaces of eggshells belonging to species of ''Dinornis'' and ''Euryapteryx'' suggest that these very thin eggs were likely to have been incubated by the lighter males. The thin nature of the eggshells of these larger species of moa, even if incubated by the male, suggests that egg breakage in these species would have been common if the typical contact method of avian egg incubation was used."<ref name="Huynen, Leon 2010"/> Despite the bird's extinction, the high yield of DNA available from recovered fossilised eggs has allowed the moa's genome to be sequenced.<ref>Yong, Ed. (2010)</ref>