It’s a sad time for the Arboretum’s osprey cam fans, who were captivated by two, then three, osprey chicks that hatched last week.
Over the weekend, one chick likely died of starvation, and another appeared to fall on its back with a full crop (a special digestive chamber found in birds), making it too heavy to flip back over.
Viewers have been heartbroken, understandably, as these little lives ended so soon. Vanessa Greene with Twin Cities Metro Osprey Watch has documented most of the details of the nest on Facebook.
Lori Arent, the Assistant Director of The Raptor Center at the College of Veterinary Medicine at the University of Minnesota, explained some of what she observed about the bird that seemed to fall over: “Birds have amazing respiratory systems, so the fact that it was on its back overnight, should not have affected its breathing,” Arent said. “The fact that it also had a full crop, however, could have. The large crop could have put pressure on its trachea and/or the chick could have aspirated some food.”
The family seemed to be interacting the afternoon of June 28.
As of this writing, one chick remains, but challenges abound for it and its parents. Among the barriers to survival are two main issues:
1: The nest is in poor shape. The buildup of organic material has offered too little protected depth for sticks to be anchored to create a nest edge, Arent said, adding that the nest should be cleaned before the next breeding season. Vanessa Greene has made the same recommendation in the past. Arboretum staff are planning to work on the nest in consultation with Vanessa Greene in the fall. The state of the nest has exacerbated recent weather conditions for the birds, including high heat and high winds.
“This is a hard situation,” Arent said. “Chick mortality for a variety of reasons is a part of nature. The lack of a true nest structure creates several unique challenges that reduce the chances that the chicks will survive to fledgling. A nest structure supports the chicks not only to keep them contained, but also hidden a bit from aerial predators (at least when very young) and helps to prevent them from toppling over and not being able to right themselves or getting what is called splayed legs.”
2: The mother appears to be inexperienced. Both Arent and Greene have observed that the mother’s behaviors are consistent with a female who is new to parenting. She has struggled at times with feeding, brooding and connecting with all the chicks.
Arent, addressing the chick which appeared to have a full crop said: “It sounds like it was not brooded all night, and the drop in body temperature alone could have resulted in its death. The female is indeed acting oddly for a breeding female.”
Arent said although there are nesting behaviors typical of different bird species, a variety of factors can lead to individual variation.
"This female is not exhibiting typical osprey behavior," Arent said. "She did not remove the dead chick right away, she left the nest and the chicks unattended and not brooded when they should not have been, and she has been reported to brood the dead chick. She is a new female to this nest site and this could be her first nesting attempt.”
The remaining chick (bottom right) spends its share of time alone in the nest on June 28.
One viewer asked: Why didn’t the mother remove the dead chick sooner or do more to prevent the loss of the chick?
Arent said there are many reports of adult osprey removing dead chicks from their nest. She said: “It should be instinctive for them to know that decaying flesh will attract insects and potentially scavengers,” Arent said. “It is not that unusual in the raptor world for first-time nesters to miss the mark on some aspects of successfully breeding and raising a clutch. There is much to know and learn about being a first-time parent.”
Thank you to all those who are for watching the nest and learning about osprey behavior, even as tragic turns take place with the birds.
If you’ve fallen in love with osprey and are hungry for more, check out the PBS Nature show, Season of the Osprey, available for rent on Amazon Prime Video.
Narrated by Paul Giamatti, it shows incredible footage of osprey flying, fishing, fighting off eagles and in their nests raising chicks on the mouth of the Connecticut River, which contains one of the highest concentrations of breeding osprey along the southern New England coast.
An osprey could be seen brooding the chick in the early hours of June 28.