Just to show how weather and food shortage (that more likely was related to a brutal weather - Osprey parents could not find enough accessible fish) can impact life in the Osprey nest check this video taken this spring.
And an important note: this particular Osprey pair had no problems during last 5 years fledging even 3 chicks during two different years. Female almost never hunted during nesting seasons in past years – this year she was providing at least half, if not more fish than male, and the pair was only able to raise one chicks that was often left alone for many hours as both parents were trying to catch fish at that time. Two younger chicks did not survive sibling rivalry and died from starvation, dehydration and probably overheating. I don’t expect anybody to enjoy watching this video, quite appositive, but I think it is interesting to see the event that is very rare to witness in person. I know only about one documented case of Osprey cannibalism. Brood reduction - cainism (siblicide – obligate and facultative) is well documented in raptors (and not only), but again, rarely witnessed. There are 4 major hypotheses trying to explain sibling aggression and siblicide: The Food-Amount Hypothesis (FAH) - the most generally accepted hypothesis, the Prey-Size Hypothesis, the Brood-Size Hypothesis and the Challenge Hypothesis. All have been supported by evidence but, however, no single hypothesis can fully explain the cause of avian siblicidal aggression. At least I could learn a lot this year when collecting observations during atypical weather/food accessibility conditions.
A few still photos illustrating the Osprey cainism are in a few folders here:
http://www.pbase.com/mbb/from_the_field - I should add more photos in the near future.