Category: Birds

Another view of the juvenile Osprey that has been feeding and resting at Milton Country Park since 5th September 2024. It is an unringed bird, so not a fledgling from the breeders at Rutland Water. It is, rather, most likely to have flown in from Scotland or Cumbria, a wild fledgling, heading to Gambia or a neighbouring country for the winter.

Usually, the adult birds tend to fly from their nesting sites right through to Africa without needing to stop over at country parks and the like. But, inexperienced juveniles, like all children, get hungry on a long journey and so this juvenile has stopped off to refuel. One person in the park reported that the juvenile had settled on their garden fence in the village briefly.

Having said that about the adults flying through, I also saw an adult at the park on the day I first saw the juvenile. More to the point, there had been reports of an adult on the Cam and possibly the same, or different bird, in nearby Chesterton and at Dernford Reservoir.

I think I missed seeing the juvenile catch a fish by minutes. When I caught up with it having hung around watching and waiting for an hour, it was eating a roach or a perch while being mobbed by corvids (magpies and jackdaws) on its usual oak perch in the park.

Pandion haliaetus – Sometimes known as the Sea Hawk, Rive Hawk, Fish Hawk. Only extant member of the genus Pandion. Molecular phylogenetic analysis shows that the Pandionidae is a sibling family to the Accipitridae and suggests that the two families diverged more than 50 million years ago. The Accipitridae includes the hawks, eagles, kites, harriers and Old World vultures.

UPDATE – 23 October 2024: The juvenile Osprey that appeared in Milton Country Park on the 5th September was last reported on its feeding perch on 21st October. It seems that it had finally headed south for the winter.

I asked expert Tim Mackrill, an ornithologist at the Roy Dennis Wildlife Foundation about the bird. “It is fairly common for juveniles to stop-over in this way during September and October, and some birds even stay into November, particularly on the South Coast [of England],” he told me. “Most juveniles depart their nest site before they have caught a fish for themselves, so if they encounter a location where they are catching fish relatively easily, they can often linger for a number of days or even weeks, as your bird did.” He adds that most Ospreys in England and Wales are ringed, but there are many Scottish sites where chicks are not ringed. “It is most likely that this was a Scottish youngster” he told me. “That said, some Scandinavian birds also pass through England on autumn migration, so that can’t be discounted either.”

If it reaches Africa, it will stay there for several seasons before flying back to somewhere near the place it hatched earlier in 2024 to seek a mate. Meanwhile, another migrating Osprey was seen at RSPB Fen Drayton on 22nd October.

Famously, there are nesting Ospreys at Rutland Water, which is probably the nearest spot we’d expect to see these breeding summer visitors. However, migrating birds on passage can turn up anywhere there’s water and fish if they sense a safe place to refuel on their journey to or from sub-Saharan Africa. I suspect the passage migrants mentioned in this post have flown in from much further north, Cumbria or Scotland, perhaps. No signs of leg rings and the Rutland birds are all ringed.

We have lots of gravel pits in this part of Cambridgeshire that have been repurposed as nature reserves and parks. One of them, Milton Country Park has seen lots of interesting birdlife over the last few years. You’re almost always going to see Kingfisher, Cormorants and various ducks and waders there as well as woodland birds and even occasionally exotic warblers. Geese numbers seem to be way down recently.

Back in late April 2014, a Eurasian Osprey turned up and hung around for a while. This was presumably a migrant heading north. The previous year one was present in September, presumably heading south. Prior to that 2008.

There’s an Osprey at Milton CP right now, first appearance, 5th September 2024 or thereabouts. It’s a juvenile. Not long after, an adult was seen on the nearby stretch of the River Cam at Bait’s Bite Lock. There have been some other local sightings in Chesterton and at Dernford Reservoir.

Mrs Sciencebase and I took a stroll around the Milton CP site on the morning of 14th September, and while we saw Kingfisher, there was no sign of any Ospreys. We had another try on the afternoon of the 15th and spotted one flying over one of the lakes. It was airborne for a few minutes before heading to a roosting point high in an oak tree, a spot others had seen it several times in previous days. We had great views of it in the air and then at its roost. It would occasionally bow, perhaps a precocious mating bow, so I suspect it’s a female. I saw no sign of it on the morning of the 16th September.

As we were leaving the park, we took one more look from a viewing jetty and saw another (adult) Osprey that had flown in from the direction of the River Cam. It had apparently fished briefly just before we saw it in the air and then it quickly disappeared back towards the river. This was definitely a second bird, as the roosting juvenile has a nick from one of its wings whereas this apparent adult did not.

County Bird Recorder, Jon Heath, interviewed in Cambridge Independent.

I’ve talked about warblers before. Basically, the warblers are a non-scientific grouping of similar birds. In the UK, we often see and hear  a variety of warblers, mostly summer visitors, among them Blackcap, Cetti’s Warbler, Chiffchaff, Garden Warbler (Sylvia borin), Grasshopper Warbler, Great Reed Warbler (occasionally), Lesser Whitethroat, Reed Warbler, Sedge Warbler, Whitethroat, and Willow Warbler.

I headed to RSPB Fen Drayton Lakes nature reserve on a promise of Arctic Terns as a big influx had been reported on Tuesday, some 36, arriving in two waves, 29 and then 7, from Grafham Water. This is a huge number for one inland patch, especially in East Anglia.

More often, we’d have Common Terns and only a sporadic appearance of single figures Arctic. I had alerted the local birding community to a Sandwich Tern on 17th April 2024. A relative rarity that unusually stuck around for several days at the reserve. We also get Black Tern on these lakes.

Anyway, I saw just a few of the Arctic Terns on the water. However, a nice patch facing out over Ferry Lagoon fringed with some very noisy trees and bushes had Garden Warbler and Sedge Warbler calling noisily alongside Chiffchaff, Lesser Whitethroat, and Willow Warbler. There were several of each species. There were also two or three Cuckoo calling from far off trees. That aside, I got a shot of one of the Garden Warblers. I thought it was my first attempt at photographing this bird, but I discovered that I had photos of it in the warbler post from 2022.

At least 43 birds on sight or sound this morning:

Footnote: We do see Grasshopper Warblers (Groppers) locally, but I didn’t today. Dartford Warbler was seen a couple of summers ago, but a fairly rare sight. I’ve seen the rather rare Wood Warbler, but not in the UK, it was up the hill in Split, Croatia, back in 2017 before we drank all that dark ale on the way down and had catfish and chips for tea.

More about the British warblers on the BBC Countryfile site here.

Yesterday, I spotted a Sandwich Tern, Thalasseus sandvicensis, colloquially known as a Sarnie, patrolling the open river lock at Brownshill Staunch on the Great River Ouse. It flew back and forth over a stretch of about 200 metres for 20 minutes or so before heading off downstream.

The river cuts through the RSPB Ouse Fen nature reserve (I’d walked in from the Over end rather than Needingworth). The lock is currently open to allow flood water to run to the sea, although it’s not flowing as violently as it was about a month ago.

Anyway, I’ve seen several Common Terns fishing on this reserve and a Black Tern fly through one pre-covid summer. But, a Sandwich seemed unusual so I posted my spot to the local patch’s birding social media group when I first saw it. There was a flurry of interest and one member, Richard Thomas, keen to see the bird, headed to the Staunch. Unfortunately, for him the bird had moved on by the time he arrived, and I hadn’t checked back in on the group after my initial update to let them know. He dipped out. My bad.

I later spoke to Richard about the presence of the Sandwich Tern. I had assumed it wasn’t a so-called mega rarity, but still its presence was rather unusual. He told me he thinks they’re almost annual in this area despite their being so obviously coastal feeders and breeders.

“Sandwich Terns are just about annual locally – I’ve seen them on six occasions in 20 years and missed them more times than that,” Richard told me. “They are an absolute pain in the neck because they rarely stay more than a few minutes. I’ve been lucky on four occasions with “fly throughs” (including a flock of seven at the Brownshill Staunch).” He added that they’re annual at Grafham Water reservoir, which isn’t far from here either and a nice birding spot, but again, he says, they were almost invariably fly throughs.

There was a subsequent flurry of activity in the social media group, my having alerted the birders to the presence of the species, and it was quickly tracked down to yet another patch of old gravel pits turned nature reserve, RSPB Fen Drayton. Several birders were excited to know it was there and surprised that it had roosted rather than flying through.

The River Great Ouse empties into The Wash on the north Norfolk coast. It’s worth noting that Brownshill Staunch, which lies on the Greenwich Meridian, is the last stretch of the river that still feels the effects of the tide. In recent weeks, my fellow togger friend Andy Hoy saw a seal sunning itself on the riverbank at this point. It had presumably swum upstream from the coast. Seals are not uncommon on the river, although they’re usually seen further downstream. In the summer of 2023, a female dolphin and two offspring were seen on this stretch of river too.

Richard has the last word in adding that one good tern deserves another, he suggests that Caspian Tern or Roseate Tern would be firsts for the patch should they turn up…

Latest intel on the Sarnie is that it’s feeding on the river near Ferry Lagoon at RSPB Fen Drayton 18h00 on the 18th April. On the 17th it roosted on the islands in the Lagoon. The bird was still being seen on 20th April. Interesting that quite rare for this species to stay in Cambridgeshire this long. Some birders said not known it before, others pointed out that one may have over-wintered at Grafham Water in 1987.

Having spent a couple of evenings watching Starling murmurations with hundreds of thousands of birds, it was time to seek out some Aves in smaller numbers. I had a quick look in at RSPB Ouse Fen (Earith) as it was bright and sunny on Saturday morning. I was hoping to that there would be a chance that the Cranes would be showing. They weren’t but there was a Great White Egret, as ever, and a Chinese Water Deer, I had only fleeting, distant views of a solitary Marsh Harrier. I headed out to Chain Corner to check on the Whooper Swans, a few on the water and one that flew right over me.

Next on to a patch of flooded farmland, often used for fen skating historically, it had lots of waterfowl, but no Glossy Ibis there this year, despite their having bred not far from here in 2023. Then on to RSPB Berry Fen, which is just a short hop further up the road. Chiffchaff calling, lots of Widgeon whistling but no Black-tailed Godwit, there were several hundred earlier last week, apparently.

There was also a distant piping Redshank and the Merlin app picked up the sound of a Green-winged Teal (it’s perhaps the same American vagrant we’ve seen here over the last two or three years; previously, there has also been a Blue-winged Teal). There had also been Dunlin and similar species there but I couldn’t see them. There was a Sparrowhawk, known affectionately as a Sprawk to birders, that flew right over me and away with its familiar flap-flap-glide flight pattern.

Further round, the flood, a group of Greylag Geese hanging out with some Russian visitors – three White-fronted Geese. This species, Anser albifrons, might better be known as “white-faced” as you can see from the photos. But as is often the wont of naturalists names sometimes don’t quite match the species description.

According to the BTO website: Two races of White-fronted Goose occur in the UK. A. albifrons (the European WfG) breeds in western Russia and is usually about 1000 to 2000 of them are found in the south and east of England in the winter. A. flavirostris breeds in western Greenland (the Greenland WfG) and about 10000-12000 of this subspecies usually spend the winter in the north and west of Britain and Ireland.

UPDATE: I mentioned the murmurations to a choir friend, Sara, and bumped into her and her husband on the Fen. I warned them that, because it was very windy, we might not get such good murmurations as I’d mentioned before. But amazingly, as dusk rolled on, even though it wasn’t a bright sunset, we got some wonderful activity from a staggering half a million Starlings.

I chunk estimated numbers from my photos and the video at perhaps 400,000. However, I then fed some photos and video stills to Google Gemini AI and asked it to process, analyse, and count the birds. Gemini estimated the size of the flock in my video from a still capture as being 500,000. There were many more birds outside the video frame, so I suspect on this evening there were between 550,000 and 650,000 birds murmurating. ChatGPT got similar numbers from my photos. Microsoft Copilot simply told me the images were of murmurations and said it was too difficult to count the number of birds.

The main activity was very much over the reedbeds among which we stood rather than being half a mile away as occurred on my previous two visits.  This made it hard to get the full murmuration in the camera frame at the level of zoom I had with me. So, the above video was done on my phone as a record.

The birds would whoosh over out heads at about 50 metres altitude. I warned the people around me not to look up with their mouths open and within a few minutes, my choir friend had undergone a full birding initiation with three deposits from above in quick succession. Amazing that I didn’t get splashed as I was standing only a metre or two away from her.

Anyway, the birds gathered in a very dense flock at about 17h50 and bedded down into the vast reedbed in front of the entrance to the reserve. There were undulations for a good ten minutes as it got darker and darker. At one point, a Merlin was reported to have caught one Starling on the wing. The other 199,999 were fine and had roosted down among the reeds by the time we departed.

At the end of February, I got wind of there being very large numbers of Common Starling murmurating at a local nature reserve – RSPB Ouse Fen (Earith). I got a few photos on an evening visit. There were probably half a million birds, it was quite astonishing. I based my estimate on counts I’ve done of photographs of smaller flocks and extrapolating to the huge patches of sky that were covered with birds on the evening.

I got some nice photos at sunset but my phone video was very smeary and low-res. So, a second visit was essential. Unfortunately, rumour had it that the numbers the next night were smaller, that some of the birds had moved to roosting over the Over side of RSPB Ouse Fen…nevertheless, Mrs Sciencebase and myself headed over to Earith on 3rd March.

It was a much better evening and definitey fewer Starlings, but still many tens of thousands. This time I got some decent video footage of the murmurations.

We also ticked three Short-eared Owls, half a dozen Chinese Water Deer, heard numerous Cetti’s Warbler and saw just one, saw Great White Egret and Grey Heron, heard a couple of Bearded Reedling, and heard one or two booming Bitterns, lots of Geese, Cormorants, Reed Bunting, Widgeon calling, Little Grebe, Water Rail etc. The Cranes that had been displaying south of the car park on the gravel works land flew in to roost about a quarter of a mile in front of us as we watched the starling murmurations. It was a wonderful evening of nature watching.

I played my video to the Merlin app, although we all knew what birds we could hear, but it came back with Coot, Greylag Goose, Canada Goose, Cetti’s Warbler, Ring-necked Pheasant. It didn’t pick up Wigeon, Little Grebe, Reed Bunting, Bearded Reedling, which we had heard.

I opened up one of my stills with a huge flock across it and enlarged it on my laptop screen. I drew a square around a patch that I estimated had 100 birds in it. Double-checked and adjusted the size of the square to make sure it was very close to 100. I measured the square in pixels and then worked out how many such squares would fill the area of the photo filled with birds. It came to about 75000 birds. This assumes average density across the photo. There were probably areas outside the area of the photo that would be around 25000 birds. So, the biggest flock would be around 100000, there were probably about half the same number of birds in the air elsewhere. The previous evening of murmurations I’d have said there were 5-6 such flocks, so guesstimating at least half a million birds going to roost on this patch of the reserve.

I’ve mentioned seeing an unringed White Stork, Ciconia ciconia, in our neighbourhood previously. It is probably a collection escapee and perhaps the same unringed bird that has in previous years been seen in Kent, Essex, and then a couple of years ago in a marina in a village not far from here called Earith and most recently near the flooded farmland on Smithy Fen in Cottenham.

Today, a friend reported that it was on a flood alongside Twentypence Road. Incidentally, it seems unlikely that this bird is a vagrant from continental Europe, but you never know. Some cynical birders would refer to an escapee as a plastic bird.

I headed out on my bike to try and catch sight of it, but it was no longer in the reported field. If only I’d checked my messages before I left, as another friend had sent me a photo from the “new” village ponds where he’d seen it and wanted to know what sort of bird it was. Anyway, Mrs Sciencebase having caught me up on Twentypence Road headed back towards home along the Cottenham Lode and spotted the bird in yet another flooded field. She called me to report in and I cycled up to see it. The sun was out for 20 minutes, so got some reasonable views of the bird standing on a mound of earth behind the old stud and stables.

At this point, we messaged some other friends who we thought might be interested and they headed in and got good views too.

You may have noticed the White Stork’s scientific binomial uses the same word for genus and species, Ciconia ciconia. The word comes from the Latin for stork, so this bird is a Stork stork, you might say. Such a repeat in a name, a tautonym, indicates that this species is the type, or archetype, of the genus. See also: Cygnus cygnus (Whooper Swan), Bufo bufo (Common Toad), Buteo buteo (Common Buzzard), Carduelis carduelis, (European Goldfinch) and, of course, Gorilla gorilla gorilla (Western Lowland Gorilla).

The White Stork was still in the same field this morning although perhaps 200 metres away, hence the lower-quality photo. But, I’m sharing it to give you a sense of size of the stork relative to the Little Egret.