Friday, June 5, 2009

Weather can directly impact productivity

In late May and early June, many eggs begin to hatch. Osprey hatchlings are considered semi-altricial at birth or are covered in down, blind and need close parental care (feeding and body warmth). For approximately the first 7-10 days the young are very vulnerable to extremes in weather conditions, especially cold and damp conditions. This spring has definitely been a cold and wet one. This week I have been constantly thinking of our osprey parents, closely brooding their eggs and young to keep warm. I hope this rain ends soon, and I also hope that it does not have too much of a negative impact on our population this year!

In 2003, productivity was below normal. Mainly caused by adverse weather conditions. It was a cold wet spring. In the 2003 Osprey Newsletter, Kathy Clark wrote:

"The most likely cause of this year’s nest failures is the weather during April and May, when ospreys were incubating and just hatching. It was unusually cool and wet, and those conditions can have several implications for ospreys: the high precipitation may have delayed fish migration and spawning, making prey harder to find; it may also have increased water turbidity, making it more difficult for ospreys to see fish. As ospreys spent more time hunting with less success, their
incubating partners may have been forced to leave the nest – exposing eggs or young chicks to
weather and predators – to hunt for themselves. In addition, we found that many young nestlings
died when they were just two to three weeks old in June and early July, most from starvation, so the
effects of the cool spring were far-reaching. Unlike previous years when nest success declined in one
region or another (primarily the Atlantic Coast), this year’s problems were statewide, which supports
the theory that weather was the predominant cause.

In approximately 2-3 weeks we will begin our annual ground survey where we collect data to help calculate the productivity rate and band young for future tracking. With this data we can determine the success of the breeding season.

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