As we enter in another breeding season characterized by the inherent challenges associated with predation, sibling rivalry (siblicide), and environmental stressors, the dynamics of osprey nesting and chick rearing will be scrutinized. It is essential to adhere to established guidelines during discussions, promoting a respectful and educational atmosphere conducive to observation and learning.
Historical data reveals the emotional complexity of observing osprey nests. Over the years, out of 18 hatched chicks, five succumbed to various natural pressures while 12 successfully fledged. In 2021, all chicks fledged; however, in 2022, two chick mortalities were recorded. These occurrences incite inquiries into the determining factors, ranging from parental care, prey availability, weather conditions, to intrinsic behavioral patterns.
During adverse weather conditions, observable aggressive behaviors amongst chicks, such as food monopolization, are noted. Siblicide, albeit distressing from a human perspective, is a natural and commonplace occurrence in raptors, including ospreys. This behavior is exacerbated during the chicks' rapid growth phase between two to four weeks of age when the demand for food peaks.
Ian Falkenberg, a noted authority in the field (more about Ian can be found at https://friendsofosprey.com.au/friends-of-osprey-committee/), asserts the natural occurrence of siblicide. He highlights the ospreys' non-interventionist approach to these survival struggles among their young. Falkenberg discourages human intervention due to poor survival outcomes and legal restrictions unless an imminent threat to the nest exists.
The observation of natural behaviors, including aggression and siblicide, is integral to our understanding of osprey ecology. It is incumbent upon observers to approach these phenomena with a scientific and objective perspective, abstaining from anthropomorphizing or prematurely drawing conclusions. This practice will facilitate a productive learning environment, reducing collective distress during challenging observational periods.
We reiterate the importance of respectful and informed discourse as we continue to observe and learn from these majestic raptors. Nature, in its raw form, presents opportunities for profound insights into osprey behavioral ecology, predation, and survival strategies. Observers are encouraged to embrace these learning opportunities, fostering a community of respect, curiosity, and shared knowledge.
Please read the following post by Ian Falkenberg after the sad situation last year when not one, but two chicks perished
"Whilst unfortunate and disappointing, as you are aware siblicide is a natural occurrence in many raptor species including Ospreys. The fastest growth period for the young is during the first 2 to 4 weeks and the highest demand for food. Given the egg hatching sequence and resulting genders with three young in the nest, two larger (probably female) and one smaller young (probably a male), it would be unlikely the smaller young would have survived. This is probably one of the reasons siblicide occurs very early in the development stage (higher demand for food) and is less likely during their feather development stage. This runty young would be at a serious disadvantage as the brood grows and matures. The adult male simply may not have been able to keep up the supply of food for all three very hungry young and as nature intended, the larger and stronger begging young, receives the most food, the result is a mortality of the weakest young to ensure the remaining two stronger young have the best chances of survival.
Any human intervention to save this young would be unlikely to result in a good outcome over the longer term and there is a wealth of evidence world wide to support this. This is one of the primary reasons intervention is discouraged as survival is very poor. In addition to the physical injuries the larger chicks inflict on the smaller young, there are likely to be psychological injuries and affects as well.
Whilst siblicide is difficult to understand from a human perspective, adult Ospreys and other raptors generally standby and do not intervene in these struggles for survival of their young. Sometimes extended brooding by the female can subdue siblicide behaviour for a time but rarely does it result in resolving conflict once the process has started. Its interesting siblicide is most prominent in the larger raptors (eg Eagles, Buzzards, Ospreys, etc) but uncommon in the Falcon group of raptors.
I believe there is no justification for human intervention and the removal of the weakest and smallest (runty) young from a nest. In this case the removal of the dead young from the nest was appropriate given the live webcam coverage and profile of the Osprey nest. In addition it is illegal to take a young from the nest without the appropriate authority and approval. The only situation I can think of where this type of action may be warranted, is where an Osprey nest is in danger from an imminent threat.
Cheers
Ian Falkenberg"