During a recent boat trip along the Connecticut River, the Captain who was very knowledgeable about the various species that reside and mate there. A member of a group of River Captains and professional agencies, he has been watching and cataloguing the details of many species that reside along the River. He focused a good deal of attention on the Osprey as they were at one time almost extinct, especially along the Connecticut River poisoned by their primary food source or unable to reproduce.
Ospreys
Ospreys are large raptors, brown on top and greyish or white on the head and breast with black winds and a black eye-strap resembling a mask. These large birds reach two feet in height with a five to six foot wing span. When in flight they hold their wings at an angle, a distinguishing feature from their cousin, the Bald Eagle who, in addition to being larger and heavier, hold their wings flat while in the air. Ospreys are considered raptors due to being diurnal hunting birds of prey in addition to possessing sharp talons used to catch their prey and sharp, hooked beaks to tear into their meal. Ospreys are considered unusual as these carnivorous birds of prey all belong to a single species yet live around the world, near bodies of water.
Osprey Nests
While we saw several large nests still intact we were informed most had been destroyed by the hurricane. However the Captain stated that many nests don’t normally survive a normal winter as they are not built as sturdily as that of the Bald Eagle. Passing an exceedingly large nest built on top of a marker, the Captain stated that the Coast Guard has to take it down every fall once the Ospreys have migrated in order to be able to access the equipment. But, he added, the same pair returns in spring to rebuild in the same location as do the other Osprey pairs that return to the river each year.
The Osprey Nears Extinction
This is another bird in addition to the Bald Eagle, we were informed, that is carefully watched due to its near extinction from an unexpected source. In the 1960’s, beaches were sprayed with the pesticide DDT. While prior to the spraying, there had been hundreds of Osprey with over 100 nests along the river, when the DDT polluted the water and the fish which were their main food source, many Osprey began to die and the ones who lived were unable to reproduce due to the thinning shells of their eggs. Before all was said and done, more than 90% of the Osprey along the New England shore had been wiped out.
By the time the effects of the DDT became known there were only two nests left downriver. Two events lead to the re-emergence of the Osprey population. First, when ornithologist Tory Peterson discovered what was happening in the 1960’s, he and his students instigated the “Osprey Egg Transfer Trials”, taking healthy eggs from Osprey in Maryland and using them to replace the unviable ones from the Connecticut birds. They did this for 5 years, and began to see a slight build up in the numbers of Osprey along the River.
However, it wasn’t until it was discovered that DDT was a carcinogen in the early 1970’s and spraying was banned in 1973 by the Clean Water Act that the true turnaround in the Osprey population began. While it took some time for the waters in the area to become free of the harmful chemicals, slowly the Osprey were able to produce increasing numbers of their own offspring and slowly they began to return to the area and increase in number. Yet they continue to be included as a protected species under the Migratory Bird Treaty Act of 1918, which prohibits the killing, wounding or capture of the species, taking part or all of its nest or removing/destroying any eggs or fledglings
While the numbers have increased over time, in the past year along the Connecticut River, we were told, the population was seen to decrease with no known reason. In 2009-2010, there were 137 active nests along the river while in 2010-2011 there were only 70. One hypothesis was that perhaps there were great horned owls, natural enemies of Osprey, that found their way into the area traveling from nest to nest killing off the fledglings and/or the adults to gain possession of the nests as these owls don’t build their own. While one such Owl had been seen in the area, none were noted to have taken over any Osprey nest prior to migration this year or last.
“We were keeping watch on all the nests and there simply weren’t more than 70 built this year. There wasn’t evidence of great horned owls attacking any of our Osprey last year either, which could have accounted for the decrease in the number of pairs who returned this season so this is unlikely,” the Captain said. “However, we have no other explanation for the decrease.”
Osprey Pairs
Similar to the Bald Eagle, Ospreys also mate for life, separating during non-mating season often ending up wide distances apart yet have no trouble reuniting with their mates as mating season approaches to travel back to their breeding ground. As opposed to Bald Eagles, however, many Osprey appear not to breed even when they are mature. This is usually due to the death of the mate or its failure to return. While Bald Eagles are said to “Mate for life but mourn for a minute,” (attributed to Julie Victoria, a member of Connecticut’s Department of Environmental Protection) it appears the Osprey does mourn a lost mate though no normal time span is known. This can be a concern especially for younger birds who lose a mate prior to being able to successfully reproduce since with each mating season that passes with an Osprey failing to breed increases the likelihood it will fail to reproduce before dying by an additional 9%.
The Effects of a Recent Hurricane on Osprey Stop-Overs
“Normally we would likely see at least a few of these birds this time of year, as some flying south from farther north will stop here to rest for a while and feed. "However,” the captain began and I sensed disappointing news,” this year due to the hurricane and the muddy water, any Osprey that may have stopped here, apparently didn’t do so. This is likely because of the inability to see the fish through the water as they flew over such that they were unable to feed.” This seemed likely, as no Osprey were spotted by anyone that day. Passing another huge nest that appeared to be close to six feet wide (we were informed that these nests are often over 5 feet wide, 3 feet deep and can weigh over 400 pounds) close enough so that we could practically reach out and touch it, I wondered if there was a silver lining to the cloud of not seeing one of these birds that day. After all, I’m not certain I’d want to get that up close and personal to a bird of prey that required a nest large enough to easily house a motorcycle!
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