Hi all, Yeah, I've often seen gallinules and coots beat up their young! At least in American Coot, studies using banded birds by Bruce Lyon and Daizaburo Shizuka, showed that parents are aggressive to the OLDEST chicks, not the youngest ones of which each parent picks a "favorite", (see "parental compensation" below), presumably to allocate food in a more fair way and thereby aid smaller chicks' survival, and ultimately optimize the brood size survival. Think of it like "Stop being a PIG, Freddy, and let your little sister have some grub too!"
**** Daizaburo Shizuka and Bruce E. Lyon Family dynamics through time: brood reduction followed by parental compensation with aggression and favouritism Abstract Parental food allocation in birds has long been a focal point for life history and parent–offspring conflict theories. In asynchronously hatching species, parents are thought to either adjust brood size through death of marginal offspring (brood reduction), or feed the disadvantaged chicks to reduce the competitive hierar- chy (parental compensation). Here, we show that parent American coots (Fulica americana) practice both strategies by switching from brood reduction to compensation across time. Late-hatching chicks suffer higher mortality only for the first few days after hatching. Later, parents begin to exhibit parental aggression towards older chicks and each parent favours a single chick, both of which are typically the youngest of the surviving offspring. The late-hatched survivors can equal or exceed their older siblings in size prior to independence. A mixed allocation strategy allows parents to compensate for the costs of competitive hierarchies while gaining the benefits of hatching asynchrony. http://lyon.eeb.ucsc.edu/files/3713/6634/2986/2013ShizukaLyonEcolLett.pdf **** And, here's my personal photo evidence: http://marieread.photoshelter.com/image?&_bqG=0&_bqH=eJxtUF1rgzAU_TX1ZS8KdWWFPKS5mVxaY0liN30JrhUrWLvWlf395UrZZFsgJ.ece0..yoO8RO_H4q18bU_xY__Z4qU9wbZ82i.jZRSGND2iAyNYU3Vd29.6.qFqmms9DO25D9AZ4FbO4lWazmJgEwOADICJVfhBJq3elr.j8m9U_h8VaIvxMOvLRESWK6sLhyYjmWmUytcwUyTROC03khsJd7mdapNpyzRX62B8quMK2IfnuZHaIbCcvuHldkjmIlyc53SBHWqb843jiVSioKbAiZVDv7GP3mn.TfXzD02JcmHZUFfX_THYjelkREH4BS1gdtk-&GI_ID= Marie Read Wildlife Photography 452 Ringwood Road Freeville NY 13068 USA Phone 607-539-6608 e-mail m...@cornell.edu Website: http://www.marieread.com Follow me on Facebook: https://www.facebook.com/Marie-Read-Wildlife-Photography-104356136271727/ ________________________________________ From: bounce-121641668-5851...@list.cornell.edu [bounce-121641668-5851...@list.cornell.edu] on behalf of AB Clark [anneb.cl...@gmail.com] Sent: Thursday, July 6, 2017 8:07 AM To: k...@empacc.net Cc: CAYUGABIRDS-L Subject: Re: [cayugabirds-l] Gallimule tough love (I hope) Hi John et al, this is well-known gallinule “parental” behavior. As many will know, birds often lay more eggs and hatch more young than they can rear. The theoretical explanation is that in a good year, when the healthiest as well as most young can be raised, parents benefit by being ready with that number in the nest. But food or conditions will be less than good in many years. Probably most such young die without direct parental actions, simply through feeding rules that favor larger chicks, or because smaller young run out of fat fuel sooner during lean patches and stop begging and die. But gallinules (moorhens in Europe) are known for directly reducing the number of young, using a behavior “touseling” (yes, it even has a name) in which adults start to peck at and drive off/down select young. According to the literature, they are likely to select less brightly colored young. The color is related to the health and immune status of the chick, so they appear to be selecting the lower quality young. In some raptors, pelicans, boobies, and egrets, larger siblings are usually the ones to peck and often kill their smaller siblings. Anne Anne B Clark 147 Hile School Rd Freeville, NY 13068 607-222-0905 anneb.cl...@gmail.com<mailto:anneb.cl...@gmail.com> On Jul 6, 2017, at 7:32 AM, k...@empacc.net<mailto:k...@empacc.net> wrote: At the Van Dyne Spoor wetlands yesterday we observed what seemed vey unusual gallinule behavior. An adult was swimming along up a small channel in the surface weeds while three young were sort of lazing around nearby. A second gallinule was a distance off. Suddenly, the adult accelerated and altered course toward one of the youngsters. When they were close, the adult came up out of the water and crash dived on top of the kid! The adult quickly surfaced and, despite watching for some time, we never saw the young reappear. The other two kids and the other adult ignored the whole affair. -- Cayugabirds-L List Info: http://www.NortheastBirding.com/CayugabirdsWELCOME http://www.NortheastBirding.com/CayugabirdsRULES http://www.NortheastBirding.com/CayugabirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/cayugabirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/Cayugabirds 3) http://birdingonthe.net/mailinglists/CAYU.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
