If you ever doubted the value of some mundane sounding citizen science projects, this story from Cornell Lab E-news is for you. Gerald Clark, a retiree who spends time enjoying birds in his backyard, was monitoring the nests of Eastern Bluebirds in Pennsylvania. A member of Project NestWatch he reported 3 normal eggs beside one large one in his bluebird box. A few days later he had 5 chicks. This is the first documented occurrence of bluebird twins!
With the frequent finding of double yolked eggs, I would not have thought it would be that rare, but apparently twins among wild birds are very rare. It turns out that the odds in wild birds are one in a billion. An article in CitizenSci describes the reasons for the rarity of twins in the wild. The twins are crowded in and one has to be able to pip the shell to hatch. In addition, both have to have access to the air cell where oxygen and carbon dioxide are exchanged through pores in the shell.
This citizen science finding was published in PeerJ, a peer reviewed journal. Details and pictures are at blog.allaboutbirds.org. All citizen science begins by being aware of the opportunities and reporting findings. Like the Christmas Bird Count and Project Monarch, getting involved is simple. Check out the Cornell Lab of Ornithology's NestWatch at this link.
Thanks to Becky Erickson of MONPS (Missouri Native Plant Society) for the lead.