Tara Tanaka (Vimeo site here, and Flickr site here) is back with a lovely video of inter-sibling rivalry between two Great Egret (Ardea alba) chicks. Her description of this avian Frog Fight is below.
Six days after videoing three young Great Egrets in this nest, I returned to find only two. The feeding process is brutal, and it’s a wonder that there aren’t a lot of one-eyed egrets. For a brief moment the chick with its back to the camera had the frog – but his joy was short-lived as the chick facing the camera immediately grabbed it from him, feet first. It was probably the backwards orientation that kept him from being able to quickly swallow it, and once again, when opportunity presented itself, the original chick quickly snatched it out of the beak and throat of his sibling. It’s not over until it’s over.
Watch on full screen and be sure to listen all the way to the end. See if you can figure out what’s supposed to be happening at the end.
And here’s an astronomy photo from reader Tim Anderson.
This is NGC5139 – the Omega Centauri globular star cluster. It is one of the glories of the Southern Hemisphere skies and is easily visible to the naked eye on a dark night. This image was compiled from eighty 60-second exposures taken with a 100mm refracting telescope and a colour astronomical camera.
Je egret rien…
https://www.cafepress.com/+egrets_ive_had_a_few_mousepad,1128043405
How different is the photo of the cluster from a photo from, say, 20 years ago – in terms of star positions? i.e. can the very slow motion of any objects in the photo be perceived if given enough years?
Jay Anderson & Roeland van der Marel of the Space Telescope Science Institute have done exactly that by comparing archived images that were recorded over four years. These were HST images taken from orbit 570 km above Earth. They measured the change in position & thus velocities [from our POV] of 100,000 or 1% of the stars in the cluster. You can find details in this 2015 article HERE
The article also says that no Earth-based professional telescope can detect this positional difference because of atmospheric blurring combined with the extreme density of stars in the cluster combined with the distance of around 16k light years. The more one zooms in, the more stars that are revealed [see image below] so it takes a mighty setup to be sure you are comparing one particular star between images & that the star is actually part of the cluster rather than something closer [for example]. I assume the article means that telescopes that error correct for variable atmospheric distortions also can’t resolve star positions accurately enough as of 2015.
https://flic.kr/p/2ek4LnV
Great narrative film, Tanaka. I watched feeding behavior at some great blue heron nests. The young grabbing the parents beak was very much the same as with the egrets, but, the result was a bit different. The parent regurgitated a load right into the nest and the chicks standing on the edge of the nest grabbed for bits seemingly without too much conflict.
Thank you Rick. They’re all similar but they all seem to have their unique styles.
Egrets and herons are, alas, well-known for their siblicidal behavior. Parents often produce more chicks than will survive, and will “permit” very severe aggression among the nestlings. Doug Mock, who was a professor at the University of Oklahoma, wrote extensively about this, and has a book on the topic called More than Kin, Less than Kind.
I recently read the same about sharks and Latimeria, where hatchlings eat their siblings (or yet-unhatched eggs) in utero. This is a cruel universe!
I think in several raptors, including some owls, it is the rule, isn’t it?
Thank you Marlene, I’ll look into that book. The parents do literally look the other way.
So do spotted hyenas and certain other mammals “Whereas siblicidal aggression is a common phenomenon in many birds (Mock 1984; Drummond et al. 1986; Mock and Parker 1997; Loughhead and Anderson 1999; Drummond 2001), the topic has been less studied in mammals, with its occurrence reported only among young pigs (Sus scrofa: Fraser and Thompson 1991), humans (Homo sapiens: Anderson 1990; Gebo 2002), Arctic foxes (Alopex lagopus: Macpherson 1969), and spotted hyenas (Crocuta crocuta: Frank et al. 1991; Hofer and East 1997; Golla et al. 1999). Reports in the literature disagree regarding whether siblicide occurs at all in spotted hyenas, and if so, whether it is facultative or obligate. Siblicide is considered “obligate” or “habitual” when aggression within a brood or litter is almost always fatal to subordinates, as is true in a number of avian species (e.g., some eagles, herons, egrets, and boobies: reviewed in Mock and Parker 1997). By contrast, in “facultative” siblicide, siblings adjust the intensity of intrabrood aggression as its costs and benefits vary with current environmental conditions (Mock and Parker 1997).” https://academic.oup.com/beheco/article/18/6/974/210999. Mick is cited several times here. But I think that the mention of humans refers to another kind or kinds of siblicide.
This abstract discusses siblicide in pigs and lynx kittens, and compares that to birds. https://www.ncbi.nlm.nih.gov/pubmed/17944114
Pronghorn antelopes also practice intrauterine siblicide. https://www.mtpr.org/post/terrible-twins-its-tough-being-pronghorn-utero
What a great trivia question – “What do pigs, spotted hyenas and humans have in common?”
Thanks for another amazing video by Tara.
Yes, thank you “for another amazing video…”; but I’m quite partial to frogs, so it was rather difficult ‘stomach’.
Thank you Nilou and Jenny, and my apology to Jenny – I love frogs too.