are osprey birds dangerous to humans

Peter Cairns/2020VISION In this blog, I touch upon the threats Ospreys still face today, as well as why it is still important to report sightings to necessary parties, in light of receiving some tragic news about one of our birds.

If allowed, Ospreys are a species that has the ability to live alongside humankind peacefully and is also a species that ignites our imagination. There is nothing quite like the thrill of watching an Osprey diving, hitting the water feet first, with its talons outstretched, primed to catch a fish. It is a moment of awe and admiration for the sheer power and grace of the species. These days, Ospreys are slowly becoming more widespread across the country, with strong populations in Scotland, Wales, northern England (Cumbria and Kielder Forest for example) and of course here in Rutland.

Thankfully, these days Ospreys are relatively ‘safe’, in comparison to other raptors in the UK, for example Hen Harriers, which are still facing heavy persecution to this very day. Of course, there are a few exceptions to this, but as a whole, they face little threat from human influences. There are some predators, like corvids, which may prey on unhatched Osprey eggs if given the chance, or there was that video that went round a while ago of a Common Buzzard snatching a young Osprey chick from the nest, but as the third largest bird of prey in the UK, Ospreys don’t have many natural threats aka predators when they are here. And even if they did have more natural threats – natural threats being those uninfluenced by human activities – at least it would be natural.

Like with any migratory species, an Osprey faces more natural threats whilst they are travelling on their migrations, which could be related to things such as weather or even predation. But there is also an increased risk of falling foul to human imposed dangers. Ospreys are seen as competition to fish stocks and persecuted in some areas; in some areas; they are at risk to getting tangled in discarded fishing nets and the ingestion of plastic – similar to many other species which rely on water bodies; and also, the chance of colliding with human built structures, such as power lines or wind turbines.

As many of you will be aware, all of the Ospreys, which fledge from the nest sites in and around Rutland, are ringed as chicks at around six weeks old. We fit each individual with two rings. The first one, on their left leg, is a metal ring, and the second on their right leg, is a blue Darvic ring. Each ring carries a unique set of numbers or codes, that act as a form of identification and work a bit like our passports do. As it wouldn’t be appropriate to recapture adult Ospreys to read the ring number on the metal ring, the number on the blue ring is enlarged enough to be read using a telescope or a camera with a suitable lens. Since each ring number is exclusive to each individual, we can build up a picture of that particular bird’s movements: for example we can learn when and where the individual travels to, their favourite fishing spots and, potentially, learn about their migration and wintering areas. But it is vital to remember all of this is only possible if sightings are reported to us, which can be done by submitting a sighting record to the Roy Dennis Wildlife Foundation by following the link below, or by contacting ourselves via email or social media.

Over the years, we have had many sightings of some of the Rutland Ospreys elsewhere in the UK and also, incredibly, abroad. This has enabled us to learn more about Ospreys’ movements, understand how Rutland Ospreys are influencing populations at other locations in the UK, as well as informing us of where some spend the winter months, and more simply, it is always fantastic to hear. Because of our ringing project, we have learnt that Rutland-fledged male, S2(15) is successfully breeding in the Netherlands; the 150th chick to fledge from Rutland, male 056, overwinters in Gambia; female CJ7 is holding territory down in Poole Harbour in Dorset; and, most recently, we have learnt that one of the juveniles from 2020, female 078, has established a wintering site at the Saloum Delta in Senegal.

We usually make the assumption that all UK Ospreys migrate to the coast of West Africa for the winter months, but because individuals are identifiable by the ring numbers, and are being reported to necessary parties, our knowledge of where Ospreys from the UK migrate to have widened. We now know that Ospreys don’t always migrate to West Africa, but spend the winter months in Spain and Portugal. I cannot really say it enough – and this is going to be a running theme for the rest of the blog – that we only are able to find out this information if people report sightings to us!

A very good example of this, is young male Osprey, 2AA, which fledged in 2016 from an offsite nest. His father was 28(10) and we know he migrated to Portugal for the winter. We would be completely oblivious to where he overwinters if it weren’t for one of our key supporters, Valerie Webber, who has been brilliant at keeping us informed of Osprey sightings, both in the UK and abroad over the years.

Valerie has very kindly written the following piece for us on how the first sighting of 2AA in Portugal in 2016, has led to new appreciations and interest in Osprey conservation in Portugal.

“Myself and Alison Elder have been running our Osprey Facebook group since 2014 (Loch Garten and Other Ospreys). We first got a sighting of Blue 2AA in September 2016 at Vila Franca de Xira, Leziria, Portugal, we thought he might move on as Ospreys often use it as a stopping off place on their way to Africa, but Blue 2AA stayed and he was seen several times that year. This sighting has led to friendships with many Portuguese people who told us of sightings of Blue 2AA and many other Ospreys. Our group now has 120 members from Portugal and they share their photos with us every winter. In 2018 I took over helping the Portuguese ID Ospreys they see, not just UK but also French, German and Finnish etc. In January 2020 myself, Alison and Kenny McGowan decided it was time we visited Vila Franca de Xira and the EVOA nature reserve which is a fantastic area for Ospreys to spend their winter, sadly we did not see Blue 2AA, but we met a lot of our Portuguese friends.”

More information about EVOA’s Tagus Estuary Birdwatching and Conservation Area, can be found by clicking here.

Of course, like with anything, there is unfortunately a flip side to this when we receive news of one of our birds being injured or worse. At this point, I would like to emphasise it is still just as significant we hear about incidents of this note, because how else can we build up a full, non-biased picture of the ecology and other factors surrounding Ospreys?

On Tuesday afternoon, we found out some devastating news, that male 2AA, which had been returning to Rutland since 2018, sadly died, as a result of – what was most likely after post mortem examinations – colliding into a high voltage power line, where he holds territory in Portugal. This danger to Ospreys is shared by many species, and is considered to be a major cause of death for other large-bodied species, from raptors, such as Bonelli’s Eagles and vultures, through to low-flight manoeuvrability species such as swans and cranes. Although, this is an awful event, it has indeed highlighted a key issue Ospreys face in the modern day world and offers us an opportunity to help raise some awareness of a shared threat Ospreys and other species face.

To leave this blog on not just a good note, but a brilliant one, is we have literally just heard that one fo the four Manton Bay juveniles from 2020, male 081, has survived his first year and has seemingly established a territory at Veta la Palma, Cota Doñana, which is one of the best places for Ospreys in Spain, after being spotted there for the first time last year on the 8th October! The area is renowned for its wetlands, as well its pine forests and the migratory species it hosts, and having visited the area myself I have to say the birdlife is absolutely incredible.

Overall, the ringing and reporting of Osprey sightings is continuing to be a success and there is no denying the majority of the observations sent in to us are the exciting news-pieces we all love to hear about and I think that can be a promising and hopeful realisation in itself. So, we ask you to please continue to send in all your sightings of Ospreys via the methods outlined above, as the more information we gather, the more the picture grows and therefore the more we can learn about the movements and habits of this fascinating bird!

The graph below is from a study done by our researchers. It shows concentrations of arsenic, cadmium, copper, lead and zinc. Contaminant concentrations are shown in the blood of osprey chicks raised along the Clark Fork River (left panel) and tributaries (right panel). Each dot represents the average of one nest over the years, and the vertical bars show the range of measurements among all chicks and years from the same nests.

In summary, no one has really tracked chicks that were raised in high-mercury environments, so we are unsure of the exact amount of mercury that ospreys can withstand. The worst-case scenario for osprey in the Clark Fork River is that they might not live very long and might occasionally be replaced by birds from less contaminated areas. By banding the osprey chicks, tracking their movements, and keeping an eye on nests along the Clark Fork River, our study attempts to close this gap.

These levels are compared against contamination in river sediments to discern patterns. Generally, concentrations in sediment decrease in the downstream direction away from the areas of higher contamination. See this study (Can a river heal itslef?) from one of our researchers about heavy metals in the Clark Fork River.

Some researchers assume that the toxicological effects of mercury in humans and birds are the same, so there must be some health effect on these ospreys. On the other hand, fish-eating predators such as ospreys must have evolved with higher mercury exposures than others, because rivers and the ocean are naturally higher-mercury environments. There is not enough scientific evidence to prove either suggestion right or wrong. For example, 3000 µg/L is in line with concentrations where researchers have found decreased reproductive success or behavioral abnormalities in birds (NPS; Bio One). Others have not found any drop in the number of chicks fledged from nests with similar or higher blood mercury concentrations (AECT).

Because the Clark Fork River ecosystem is a part of a sizable Superfund complex, people are concerned about its health. Arsenic, cadmium, copper, lead, and zinc were among the toxic elements found in waste material originating from large-scale copper mining and processing operations near Butte and Anaconda. By the middle of the 20th century, the fish had virtually disappeared from the impacted headwaters of the Clark Fork River, severely damaging the aquatic ecosystem. The Anaconda Smelter’s poisonous air fall is said to have killed cattle in the Deer Lodge valley, demonstrating that environmental harm wasn’t just restricted to the rivers.

All things considered, the reporting and ringing of Osprey sightings is still going strong, and most of the observations that are sent in to us are the exciting news stories that we all enjoy reading about. That, in and of itself, can be a hopeful and promising realization. Therefore, we kindly ask that you keep reporting all of your osprey sightings using the above-mentioned methods. The more data we collect, the more the picture expands, and the more we can learn about the habits and movements of this amazing bird!

We learned with great sadness on Tuesday afternoon that the male 2AA, who had been visiting Rutland since 2018, had tragically passed away after—likely following postmortem investigations—collision with a high-voltage power line near his Portuguese territory. Many species share this threat to ospreys, and it is thought to be a primary cause of mortality for other large-bodied species, including raptors like Bonelli’s Eagles and vultures as well as low-flying maneuverability species like swans and cranes. Even though this is a terrible incident, it has brought attention to a significant problem that ospreys face in the contemporary world and gives us a chance to help spread awareness of a threat that ospreys and other species face in common.

Fortunately, compared to other raptors in the UK, such as Hen Harriers, who continue to face severe persecution to this day, ospreys are comparatively “safe” these days. They are generally not threatened by human influences, though there are a few exceptions. The third largest bird of prey in the UK, ospreys don’t have many natural threats, or predators, when they are here. However, some predators, like corvids, may prey on unhatched osprey eggs if given the chance, and there was that video that went viral a while ago of a Common Buzzard snatching a young osprey chick from the nest. Furthermore, even in the unlikely event that they faced more natural threats—that is, threats unaffected by human activity—at least it would be natural.

Normally, we assume that all UK ospreys migrate to the coast of West Africa for the winter. However, since individual ring numbers are identifiable and are reported to the appropriate parties, our understanding of the migration routes of UK ospreys has expanded. It is now known that ospreys spend the winter in Spain and Portugal rather than always migrating to West Africa. I can’t stress this enough, and it will be a recurring topic for the remainder of the blog: we are the only ones who can learn this information if people notify us about sightings!

A prime example of this is the young male Osprey, 2AA, which left its off-site nest in 2016 and fledged. We know that his father, who was 28(10), moved to Portugal for the winter. Without Valerie Webber, one of our main supporters, who has been fantastic at keeping us updated on Osprey sightings, both in the UK and abroad over the years, we would have no idea where he overwinters.


Are ospreys aggressive?

Adults are protective of the nest site and may exhibit aggressive behavior at the approach of a potential intruder. The month-long incubation period is usually completed by the female, who is fed by the male during this time.

Can an osprey pick up a dog?

Ospreys are birds of prey, they swoop down and grab up big fish, smaller birds, rabbits, and your small dog is easy game. Protect your pet and discourage the bird from your yard. He might be calculating how to snag pooch.

Is it illegal to remove an osprey nest?

Osprey, active nests, eggs, and young are also protected under the Federal Migratory Bird Treaty Act and state Rule 68A-16.001, F.A.C. Inactive nests (i.e., nests without eggs or flightless young) can be removed without a permit.

How rare is it to see an osprey?

Ospreys are pretty common in some areas of the USA. The East Coast into Florida, along the Gulf of Mexico and the California coastal area. They range inland quite a bit in Oregon and Washington and on the southern coastal area of Alaska.