Look for 2 adults on the nest. The adult pair will show pair bonding behaviors such as vocalizations, aerial sky dances, and the male feeding the female fish. You may see the pair copulating, which typically begins 14 days before laying eggs.
Females will lay 1 - 4 eggs at a rate of one egg every 1 - 2 days. After laying, incubation starts. Look for adults taking turns sitting low in the nest incubating eggs. The incubation period can last 35 - 43 days.
Chicks hatch ~39 days after incubation begins. Look for adults bringing food to the nest and making "head bows" into the center. Chicks typically can't be seen until they are 2 - 3 weeks old, so feeding behavior is the only way to know chicks are there.
Around 4 weeks after hatching, look for the heads of chicks to show over the rim of the nest, particularly when adults bring food to the nest. Other times they lie flat and are harder to see. Count the number of chicks in the nest before they learn to fly
Chicks begin flying around 7 - 8 weeks old, and are still fed by the adults. Count the number of chicks who have successfully fledged the nest and are observed flying.
Chick Last Observed
4 - 10 weeks after fledging, chicks begin leaving the nest area to migrate south, once they have learned to fly and feed themselves. Record the date that the last chick left the nest.
Look for signs of nest failure like adult abandonment, adults no longer incubating eggs or feeding young.
I got a text message today from Doreen, my contact at the township building. She said she sees the osprey pair regularly flying around and perching on the tower. So, they are still around the area but haven't been there the last several times I stopped and looked for them.
1:00 p.m. I was driving past this nest and stopped to look on route 94. I saw nothing. I pulled into the Knowlton Township municipal building, and still saw no ospreys at or near the tower. I guess this pair has moved on. I hoped they would actually lay eggs this year.
8:45 a.m. From route 94 I pulled off across from the tower and could hear and see the female loudly calling and sitting on the nest which was substantially built by the eagle pair on the second tier. I did not see the mate while I was there, nor after I moved to the Knowlton Municipal Building lot to watch. The entire time I watched, the female sat there.
The history is that this was traditionally an osprey nest but since I have watched (for the last 4 years) there has not been any nesting material nor ospreys, on this tower.
Then, last July, while riding my bike back to Knowlton Muni where we had parked, I was shocked to see the nest on the second tier.
I went into the building and met a woman who said she had watched an eagle pair build the nest in early July! She agreed to watch and report, and we exchanged emails during last summer including photos she took of the eagles. I also watched and once I even saw an eagle on the tower. The eagles moved on. It appears that an osprey pair may be staking a territory claim. The osprey seem to have added sticks to this nest since last summer.
9:30 a.m. We watched a pair of ospreys on this tower nest from the northbound side of route 94. We then moved to the Knowlton Municipal Building less than 1/4 mile away. We notice one of the adults fly off as we pulled into the parking lot. The other stayed longer, then it also flew off. This is surely a new, different pair than the pair which nested here some years ago. We do know that a pair of eagles built this nest in June/July 2022. They did not stay so it was just a "housekeeping" nest for the eagles.
9:15 a.m. Two adults were perched on the tower, next to the nest, which an eagle pair built beginning July 2022. Any nesting materials that ospreys used in the past had been cleaned off, I assumed by the cell company, when I began watching the tower in 2019. A Knowlton employee, who works in the municipal building, and I watched this eagle pair bring sticks to the tower, building a substantial nest for several weeks before they left for good. I have been watching this tower since 2019 and this is the first time I saw an osprey pair on the tower, near the nest. The nest itself appears to have been built up a bit more than it was last August.
9:15 a.m. When I arrived I saw at least half dozen ravens perched and flying around the tower, but no eagles! I spoke with Doreen at the township offices. She was sure she saw eagles yesterday and was very excited at the prospect of having nesting eagles near her office! I gave her an osprey brochure as I had already given her an eagle brochure when I gave her my card.
Doreen wrote to me at 10:53 a.m. that the eagle pair was at the nest. I was already at the osprey nest on Strykers Rd by the time I read the email. I requested that she send a phone photo next time she sees them at this nest, even if the photo isn't so sharp.
8:30 a.m. I received a call from Doreen at the Knowlton Twp building. She said there were at least three eagles at the nest on the tower! She said there may have even been a fourth flying around the area. These eagles might be two pair, and one of the pair has built a "housekeeping nest" on what had been an osprey tower! I will keep my eyes on what unfolds! It is an odd time of year for nest building!
2:15 p.m. After doing osprey nest checks in northern Warren County, I rode my bike in the area. We always meet and park in the large lot behind the Knowlton Municipal Building. As we finished the ride and were passing by the tower, I was shocked to see what appeared to be large birds on the posts and a nest on the second tier!!
Every year since I began surveying northwest Jersey osprey nests, I have checked this tower, and had never seen signs of any nest material nor any birds near the tower.
I set up my scope and sure enough, there was nesting material there although the nest did not look large nor "complete." The "birds" that I thought I could see either flew off, or I mistook part of the structure for a large, dark bird.
We meet in this parking lot to ride in the area quite frequently. In additon I drive right past this tower every time I do an eagle nest check in the water gap area--at least once a week. I always look at the tower! However, since mid-June I have not paid much attention to it since I had never seen any sign of nesting there.
I spoke with a woman (Doreen) who works in the building and goes out behind the building to smoke. She said about 3 weeks ago they were noticing large bird(s) carrying big sticks to the tower! Lately, this activity has not been observed. She seemed to feel that it was only about 3 weeks ago that the activity was initiated, and, indeed, on May 10 when I took my 2022 report photo, there was no sign of any nest material. This is very late for ospreys and eagles to be nest building. It must be a new pair building a "housekeeping" nest. It will be interesting to see what happens next season.
Doreen was not clear as to the type of bird, just that it was very large and carrying huge long sticks! Strangely, as we cycled into the parking lot, I heard an adult eagle calling (but not toward the tower, toward the other side of the building) but could not locate it in the dense foliage. I doubt an eagle would build a nest on the second tier of a tower. It is more likely ospreys that brought in the sticks!
I have been by this tower numerous times during the past two years as we often park at the municipal center to begin bike rides in the area. I have not seen any evidence of osprey nor any nesting materials on this tower.