Ospreys on the Tuolumne River

There's kind of a feeling of expectation along the Tuolumne River these last few mornings. The birds have been fewer in number, as the tropical species have started to disappear, and it's still early for many of the Arctic migrants to be appearing (but they're coming). On the other hand, some birds are here year-round, and one of the spectacular ones is the Osprey (Pandion haliaetus). Several of them have been hanging out along the Tuolumne Parkway Trail for the last week or two.

One can understand why they're around...the river is running clear, and it's full of fish, the favorite prey of the Osprey. I haven't had the chance to see one diving into the river yet, but the other evening we were on the bluffs waiting for the Harvest Moon to rise over the bluffs and saw one eating a meal.

Since it didn't fly off, I got a few moments of video as well...

The Problem of Scale and Zoom: What is That Up There?

I went out to Robert's Ferry Bridge on the Tuolumne River today to see if the Ospreys had returned to their platform on the south side of the river. It felt like time was passing without any Osprey sightings and I was worried whether they would be back at all. I was also curious if there were any birds nesting in the bridge structure, since I knew of several stick pile nests, but I couldn't tell if any birds were present.

It was really difficult to see the nests because they were in the eaves and framed by very bright skies. I had to depend on the camera to lighten up the darkness up in the eaves and I snapped a couple of shots. On the small screen of my camera the pictures seemed to show a bit of bird tail, and there was some kind of yellow thing, but I couldn't make out what it was, maybe part of the bridge superstructure, or a piece of plastic in the nest perhaps. It wasn't until I saw the pictures on my computer that I realized that my sense of scale was way off. It wasn't a bird tail at all! But at least I know who's on the nest ("who"...do you see what I did there? Do you get it?).

So, add a Great Horned Owl to the list of nesting birds in my area. Oh, and the Ospreys? They were there, both of them. They didn't seem too concerned about the herb garden growing in their nest. Now we watch and wait for all the babies to hatch!

Osprey on the Tuolumne Parkway Trail

Ospreys (Pandion haliaetus) are a regular sight on the foothill rivers coming off of the Sierra Nevada, but it's always kind of a thrill. I was walking along the Tuolumne River Parkway Trail the other day watching for small songbirds in the trees and all of the sudden I was aware that some kind of very large bird was staring at me. And they have very intense eyes. Luckily, they are far more interested in fish than they are in me!

The river runs low this time of year as the operators at Don Pedro Reservoir upstream are very sparing with their water releases. The water is shallow and clear, so I guess the fishing is pretty good for the Ospreys (and the salmon run will be starting soon).

Osprey Enjoying a Meal on the Tuolumne Parkway Trail

I'm seeing more birds along the Tuolumne Parkway Trail these days. I'm not sure of the reason, but I'm happy enough to try and photograph them. This Osprey (Pandion haliaetus) has been a fairly uncommon sight on this part of the river where it exits the Sierra Nevada and rolls into the Great Valley. They aren't rare as such. I've been monitoring a number of nests just upstream, so I know they are always around. I just don't see them on this section of trail.

This one had been successful at catching a fish of indeterminate species and was enjoying lunch in one of the dead cottonwood trees on the north side of the river. It kept an eye on me as I walked by, but didn't care enough to fly away (it was perched farther away than it looks; I was zooming in).

Ospreys Nesting on the Tuolumne River

It's spring and the big birds are nesting. We've kept an eye on four or five Osprey nests that we know of in our region on the Tuolumne, Stanislaus and Merced Rivers. One by the Roberts Ferry Bridge didn't have any occupants last we looked, but another nest between Turlock Lake and the Tuolumne River was certainly occupied last week. Both mom and dad were hanging out nearby. I'm sure we'll check up on the chick's progress as the weeks roll on.

The Osprey (Pandion haliaetus) is one of the few success stories in the bird world in the sense that we just about wiped them out with DDT last century and finally came to our senses. They have expanded their range and their population has grown, especially when posts have been provided where they can build their humungous nests.

It was certainly a pretty day last week when we went hunting birds in the foothills of the Sierra Nevada. The snowy high country contrasted strongly with the green slopes around the reservoir.

Ospreys Nesting on the Merced River

We made a quick afternoon trip a few weeks ago up the Merced River. We hadn't planned to, but we ultimately reached Yosemite Valley as the sun sank below the horizon. Along the way we stopped at Merced Falls, a Gold Rush era settlement built at the point where the Merced River flows from the Sierra into the Great Valley. It was nearly spring and we wanted to see if the Ospreys were doing okay.

Ospreys (Pandion haliaetus) nest high in sturdy trees or on telephone poles. In many areas, platforms on poles have been built just for these birds, and there is one near Merced Falls. We didn't see any birds on the platform, but an old telephone pole near the bridge serves as a second nesting site in the area. Much to our delight, a pair of Ospreys were there. One was guarding the nest and the other was soaring over the area, keeping an eye on things.

Ospreys feed almost exclusively on fish, so the Merced Falls site makes sense. There is a forebay (a shallow reservoir) that provides some excellent fishing opportunities for the birds. We've seen them do their graceful dive into the water and they usually come up with a meal.

Ospreys are a recovering species. They were almost done in by DDT back in the 60s and 70s, but once the pesticide was banned, they started returning to their old habitats. It would have been a shame to lose them. They're a beautiful sight soaring over our local lakes and rivers.

An Inventory of Osprey's Nests on the Tuolumne and Merced Rivers

We can't resist the urge to check the Mother Lode Osprey nests each week when we get a chance to go outdoors. There are at least four of them along the lower reaches of the Tuolumne and Merced Rivers that we've found so far, and a fifth hidden in the forest near Table Mountain in the drainage of the Stanislaus River.

The birds themselves are spectacular to watch, if they are out and about. They have a huge wingspan, and are graceful flyers.

Activity at the nests is pretty muted, as we have yet to see any chicks. They may very well be there, but the nests are huge and deep. They are used year after year, and each year brings new sticks and other nest materials. The largest nests can be thirteen feet deep and six or seven feet wide. They have been encouraged to use artificial poles and platforms in our region.

There is a nest at the south end of Roberts Ferry Bridge on the Tuolumne River east of Waterford.

There is another nest on an old telephone pole almost hidden in the trees just south of the Merced River near McSwain Dam. One of the biggest nests is on a pole at the junction of Merced Falls Road and Hornitos Road at Merced Falls (below).

The nearest nest to us is on Lake Road just east of Turlock Lake State Recreation Area. The Ospreys there have both the reservoir and the Tuolumne River to utilize as a source of fish.

Under the category of "what did they ever do before telephone poles?", here is an Osprey nest in the top of a conifer tree near Table Mountain and Jamestown that I saw on a hike last week.

I wonder how often such nests collapse under their own weight?

We'll keep an eye out for young Ospreys and let you know when we get some pictures!

Ospreys nesting near Turlock Lake

I did a brief little explore on Sunday to the area around Turlock Lake and the Joe Domecq Wilderness on the Tuolumne River in the Sierra Nevada foothills. There were a fair number of birds out and about, including Meadowlarks, Red-winged Blackbirds, and Western Kingbirds. The attention-getter of the day were the Ospreys (Pandion haliaetus).

The Ospreys are common in the area, as the Tuolumne River and Turlock Lake both provide plentiful fish. It's nesting season, and I saw two different nests as I explored.

The nests are massive. According to Cornell, they can reach 13 feet deep and 7 feet across. It makes one wonder how the trees or poles don't fall down (or maybe they do).

Bird of the Day: Ospreys at Merced Falls

Ospreys are great hunters of fish. There is a pretty good spot in our area to see them at work. It's along the Merced River near the village of Merced Falls. This is the place where the Merced emerges from the foothills onto the floor of the San Joaquin Valley. There are four reservoirs along this stretch, huge New Exchequer Dam, forming McClure Lake, and three much smaller dams, McSwain, Merced Falls, and Crocker-Huffman. The smaller lakes are wide and shallow, offering some good fishing possibilities for the Osprey population. We saw them at work yesterday, not so much fishing, but enjoying the fruits of their labor. Every Osprey we saw had a fish (there were at least three of them). To judge from the picture above, they saw us too.

It was easy to see why the fishing was good. Merced Falls lake was way down so the water was shallow, and the resident fish had much less shelter to hide in. In the picture below all the rocks in the background are usually submerged.

The Merced River is currently the southernmost Sierra Nevada River that supports salmon, but as of 2007, they were not able to get past Crocker-Huffman dam about three miles downstream of our location. There was a feasibility study in 2007 that explored the possibility extending their range, but I don't know if anything was done about it. I'm sure the Ospreys would be in favor of it!

Ospreys (Pandion haliaetus) are well-adapted to fishing, able to dive as much as three feet into the water to capture their prey (fish makes up 99% of their diet). They have barbs on their feet that allow them to grip their slippery targets.

The widespread use of DDT in the 1950s and 1960s nearly did in the Osprey. Their population crashed, and it was only after the use of the pesticide was banned that their numbers began to climb again. According to the Cornell Bird site, there are about 500,000 across North and South America.

There is a huge Osprey nest on a post near the reservoir. We'll be keeping an eye on developments there during the spring!