By 11:44:36, Tiny Tot had precisely nine bites of fish and a piece of fish skin.
I have felt, like so many others, gutted. Tiny Tot has survived, well beyond the first couple of weeks, through food famines and intimidation. Neither 1 or 2 pecked it to death and, indeed, if they had directly wanted to kill Tiny Tot, it would have been easier when he was smaller. Instead, the need for more food on this nest has been the main driver of the pecks and the intimidation directly and indirectly on Tiny Tot.
There are general reasons for siblicide to occur and the one most common to Ospreys is when food either becomes scarce or is perceived to be scarce. On the Achieva Osprey, this takes the form of both direct and indirect aggression to Tiny Tot. #2 sibling hovers over Tiny Tot to frighten him even though Tiny Tot might have been the first up to be fed. Individuals might also have noticed that even though #2 sibling is full, it will come and demand that Diane, the mother, feed it, instead of Tiny Tot. So, instead of direct pecking leading to death, the threats from #2 might cause Tiny Tot to starve to death. The elimination of Tiny Tot just before the older siblings fledge has no benefit to them in terms of food competition. They are grown and will not starve to death if he eats.
What I have been fighting against is the simplicity of the argument that eliminating Tiny is advantageous to both 1 and 2. As Mock et al state in their article, Avian Siblicide (1990), ‘According to this simple analysis, natural selection should always reward the most selfish act, and siblicide is the epitome of selfishness.’ Even looking at the work of Mendel and that of several British geneticists, the authors understand that helping a sibling assists the entire family – in this case ospreys – to survive. They ask, ‘Since selection favours genes that promote their own numerical increase, what advantage might there be in destroying a sibling – an organism with a high probability of carrying one’s own genes?‘ To continue to understand what could be playing out on the Achieva nest, we have to look at the youngest sibling as the marginal individual. If Tiny Tot were to survive, Diane and Jack would congratulate themselves in the way birds do on raising three healthy chicks to fledge. It is parental success! And when everyone worried that chick #2 had crop rot, Tiny Tot would have been a replacement for that bird had it died. Tiny Tot is a kind of insurance policy.
Food shortages appear to persist at the Achieva Osprey nest and those food shortages along with periods of bad weather have certainly contributed to instability. In addition, the frequency of food deliveries appears to have stimulated the aggression on this nest. Indeed, Diane, the mother, has waited to feed her chicks with no fish arriving until late afternoons sometimes. She has taken it upon herself, like today, to go and fish in order that she has food herself. She has ignored Tiny Tot at times when he is screaming and wanting to be fed – feeding instead the two older siblings. Chick #2 has been aggressive towards the mother. When Diane was feeding Tiny Tot in the wind today, even though #2 was full, it heard Tiny Tot crying for food and came and interfered in the feeding. Does chick #2 intimidate Diane the mother who is hungry and tired? Chick 2 is larger now than Diane is. Diane has had to do all of the roles on the nest. Interestingly, for two days now fish have been left on the nest in anticipation that either 1 or 2 or both would begin self-feeding. The only chick to have done this is Tiny Tot – and that was for survival. I suggest that if allowed, Tiny Tot would be feeding itself from the fish brought onto the nest provided they were unzipped far sooner than its two older siblings who simply seem to not understand what to do with the fish attached to their talons when they step on it. Perhaps this has been a blessing in disguise as Diane has fed Tiny and if the bigger ones mantled all the deliveries and ate them, would Tiny get any food? We don’t know.
So today, five fish have now been delivered to the nest. At 3:55:01 Diane brings in one of her huge catfish. There is going to be a lot of bone and skin but, the other two had three other deliveries including a large fish coming in at 1:01:20. Surely to goodness both Diane and Tiny Tot will get some of this whopper.
Tiny Tot got himself right up by Diane. If he is going to be fed, this is the place to be. The two big siblings cannot be that hungry. Look at Diane’s thin legs. They say that the parents, especially the mother birds, lose weight taking care of the chicks. It is often cited as being at least 30% of their body weight. Some bird species only breed every other year so that the adults can get into good physical shape. A good example of are the Albatross. I wonder why evolution has not allowed for that in other species like the Osprey?
I love this image. Both 1 and 2 are still up at the rim of the nest but there is Diane feeding Tiny Tot. Yesterday, I wondered if she had decided to stop feeding him.
In reality, Tiny needs to survive the self-feeding and fledging of the two older siblings. Then Diane can feed him and her alone. He is determined and clever and I would hope that those qualities might trump selfishness. But that is me being human.
It is 5:11 and Diane has been feeding Tiny Tot and 2 has decided to get antsy and aggressive. Tiny is very aware of what is happening. That is one reason he has survived.
I wonder how much food Tiny Tot will get?
In the image below, 2 is walking away from Diane. 1 is still up wanting some bites and Tiny Tot has his eye open. He is listening and watching for a chance of more fish.
There is still more fish. You can see it between Diane’s legs above. It is hoped that Tiny will get another opportunity to feed. But, he got some nice big bites of fish, more than the nine that he had this morning. Everything helps him live for another day. Some people wonder why he doesn’t fight? My first response is it uses up too much precious energy. And being clever, Tiny would know that the others are too big now and could if they wanted kill him. So Tiny Tot is being smart and taking advantage of any opening for food he can – whether it is chewing a bone or sticking right up front with Diane as long as he can!
The fifth fish came in at 7:33:46. Diane fed the older siblings and at around 7:46 she began to feed Tiny Tot and did so for approximately eight minutes. So he has gotten food from at least three fish – not huge amounts but food nonetheless. Remember, Tiny Tot just has to survive the older two til they fledge and hopefully he will be fed well til he can fledge. It needs to be noted that the older ones will also require supplemental feedings after fledging so it could get a bit tricky.
Thank you for joining me on this update. Please send your warm wishes to this nest. At midnight the weather is showing a 40% chance of thunderstorms increasing to 80% during the day on Monday and 90% on Tuesday. Tiny needs all the food he can muster!
Thank you to the Achieva Credit Union in Dunedin, Florida for their streaming cam. That is where I took my screen shots.
Good article on siblicide comparing five bird species: Mock, Drummond, and Stinson (1990). ‘ Avian Siblicide.’ American Scientist, 78, pp. 438-449.