Hoo island Herons

Another of my speck shots, just under the kilometre from Finsborough to Hoo island where, especially at this time of year, Grey Herons assemble. Several spread along the revetments as far as Folly Point, but the gathering at the old pier, a dozen in all today, always intrigues me.

Voisin's family monograph, 'The Herons of Europe', points to there being little known on courtship behaviour away from colonies- essentially, even though the species has recognised 'gathering grounds', sexual behaviour (courtship displays) do not take place on them. However, the book describes the little known dance display (perhaps little known because it is all rather unimpressive and over in a flash, a bit of one foot in, one foot out, shake it about, flap wings once and over). I've been watching, but not seeing. Makes you then wonder whether, like the Berengrave non-breeders' spring roost, these might be younger birds, not about to pair. Whatever the answer, now is the time of year for peak counts along the southern Medway. Counting gatherings here, and elsewhere, plus the routine feeding flights to inland ponds, soon provides a thirty-plus figure, a little higher than the WeBS current five-year average for the whole estuary of 21.

The other puzzling thing is still how infrequent flights between the north and south shores are. Perhaps because individual, perhaps because often pre-dawn? Certainly true flocks most often encountered in the autumn. Additionally mapping year round flightlines, the preference for avoiding the largest stretches of open water remains:

The question is how much of a role does the south Medway have as a core area for birds from the large Northward Hill heronry (circled, just north of the estuary). Data collected to date may not reflect how much local populations rely on the estuary at this time of year. The latest BTO Birdtrends results state the causes of the recent decline in breeding populations to be as yet unknown. And more notes from the head of the estuary, around St Mary's would be something to consider in the future in relation to routine crossings- I have a hunch that area could yet prove as busy as just east of Hoo Island.

And of course, as discussed recently, there could also be a few continentals hanging on- and definitely one Scandi bird has been found on the estuary before.

So many questions..

The sum of all parts of the quarry (4): non-passerines

This December, the two roost counts at Berengrave are far apart, thanks to surgery. Time to muse on what gets counted. OCD muppet that I am, I try to count everything. Results? All 'normal', but all fascinating, and helping to refine my personal views on the local populations.

This is just one small relatively insignificant, often overlooked, reserve. But look hard enough and there's enough question to keep a birder (even a bed-ridden post-op one) happy.


The non-passerines

Grey Heron
A conversation with one of the rangers a couple of years backwent something along the lines of 'Grey Herons roost in the pit, for a part of each spring.'
'So, they're breeding? Great record.'
'Nope. Show absolutely no interest in that sort of thing. I'm guessing first-summer birds that aren't being tolerated at the main heronries. or Scandi winterers hanging on- the first summer birds go back late.'
Quiet. A sad look, clearly wanted breeders. Well, one of those is right, for sure, but this sort of thing is something the most guidebooks don't really cover. Not all first-summer Grey Herons breed. Small numbers just coming in on dusk, a little squabbling, a chase now and then, but no pairing/courtship seen. Only for that period before hatching and active nesters tolerate congeners in the roost again. I try to make myself think they could be continental birds getting ready to return, but can't quite bring myself to favour that theory- yet. They usually spend the year away from their natal grounds. These birds disappear after a short period. Of course, they could wander I suppose? It pains me not to know (but that could be this is the first write-up of the morning and the meds haven't kicked in yet). Roll on February and March.

Sparrowhawk

This is a bit of a cheat, so I hang my head in shame. I can't really be sure these all stayed in the quarry after dark, but they sure were hunting roosters, and if they had any luck, went to trees on the edge of the pit. Early high counts might represent migrants, perhaps more likely local dispersals. Mid-winter peaks a concentration on prey, similar to numbers hitting a more open Starling roost; flight activity on low count evenings often suggests local residents.
So, yup, perhaps a cheat, but the doctors said I need some incentives to get back on my feet as soon as possible, and seeing if the recent high counts hold up is a good 'un.

Green Woodpecker
Doesn't say much except for there's usually a couple of pairs breed in and around the quarry. Most feeding takes place in the open field around the pit, so inbound flights are relatively easy to pick up. GreWos already present often announce an arrival as they make a territorial announcement, so I'd almost say they were guaranteed- except for that midwinter drop-off. Will this pattern continue?

Great Spotted Woodpecker
Although an odd call alerts you to a bird hidden in the pit, this species is also really easy to pick up flighting in, more often than not from all angles south, presumably from venturing to Rainham's garden feeding stations.

Stock Dove

One of the winter delights for me. Local Stock Dove roosts. I have a couple of regularly-used three figure roosts out in nearby countryside. At both I've seen Stock Doves getting shot at. Sadly, many shooters don't have the discipline of a wildfowler, an appreciation for the subtle differences between the common quarry (Woodpigeon) and the amber-listed off-limits. ("Eh? What's a Stock Dove then?") Sadly, the similar discipline of respect for neighbours is often lacking as well- the shooters are often trespassing.
So, Berengrave being so close as 1,500 metres to highly attractive feeding areas, I've often hoped more would join the Woodpigeons. Not yet to be, the graph reflecting, for the main part, the size and scale of local breeding.
Another example of how such a dull count can help incentivise your birding. Perhaps late December '17 will be the time? (Seriously, I'm on strong medication here.)

Collared Dove

This is a big disappointment. Just over a kilometre north, more than a hundred gather to be fed in the bird-friendliest garden on Motney. A k-and-a-half north-east, similar counts on the local game farm. Collared Doves are known to fly up to seven km to communal roosts, it would seem Berengrave has something going for it, and yet...

a) They want dense cover- thick conifers are used, holly and hawthorn a reasonable choice, and dense ivy another good spot. The first is somewhat lacking, the last something targeted whenever management is thought about. Of course, not every bird does as others, and individual/paired roosting in winter is a norm for many- it seems we have just a few of the local birds showing themselves from time to time.
b) They are wimps. Roosts can often be disturbed by just the threat of potential attack from predators.
c) They readily change sites, and might not return for some time. Where the seven kilometre range comes in handy.
This is the trouble with oft-overlooked species. They make you look harder. This is one species I'd enjoy stumbling on en masse one afternoon, one local roost I'd really like to pin down. (Yes, I write this, post-op laid out in my jimmy-jams, blissfully co-codamal-ed to the point the Bee-Eaters on the cover of Birds of the Western Palearctic are talking to me. But, honestly, I've really wanted that roost for some time now..)

Horrid autumn- 26/9/17

6:35-8:05

Viz mig (west)- Brent Goose 125, Grey Heron 8 (south-west), Meadow Pipit 16, Chaffinch 5, Linnet 9.
Viz mig (inland, south)- Sandwich Tern 11, Brent Goose 208.

Sun up, sun down, Brent on the inland route once again.

Another 440 south-west in the last hour of the day. The lunchtime walk had also been on this stretch, with just three Brent loafing near Bloors; clearly behaving correctly, spending the middle part of the day feeding (it should really only take the dawn flights a couple of hours to reach south coast feeding grounds). 

Horrid autumn- 2/9/17

Distant odd goings on with the Grey Herons- seven at the tip of Ham Green struck out north, twice, only to give up and turn back.

Nearer odd 'goings off'- the Friars Curlew had given up and moved to Oakham, perhaps down to the opening of the wildfowling season the previous day. It was interesting to watch birds arriving from Ham Green (usually roosting Greenborough), only to skirt Friars and circle Oakham before finally setting down.

-----------
02/09/17

Pt- Whitethroat 2, Willow Warbler, Chiffchaff, Blackcap 2, Lesser Whitethroat 2.

vm- Yellow Wagtail 4 west, Greenshank 1 high west, Golden Plover 6 west, Meadow Pipit 3 west.

Offshore- One Peregrine hunting the Rainham mudflats, last seen heading off over Otterham. Common Tern 5, Sandwich Tern 2.

Singles nights

The texts will tell you first summer non-breeding Grey Herons will attend their heronry, staying mainly to the edges, being tolerated (just) by the adults there, with only a small handful breeding (most first attempt breed at the age of two).

Some locals fail to read these texts and go awol each spring.

From about the time the adult birds start displaying, right up until the eggs are hatched, a small roost comes into operation in Berengrave LNR. Small indeed, only getting up to around double figures, but regular, happening each year since I started counting the Magpie roost there in 2013.

One or two might already be in position an hour before sunset, with the last join in nigh-blackness. I say the last, Herons are famous for arriving at roost at all sorts of time of day and night, depending on their feeding preferences (some crepuscular feeders, a few, nocturnal).

During the 90  minutes or so I'll spend there, squabbling always happens. Birds might join in aerial chases for ten, fifteen minutes over the old flooded chalkpit, but eventually they all settle down together, high up in the trees along the water's edge. This favoured area is extremely close to the main path, but they have learned to ignore the few dogwalkers that pass by, heads down.

If I mention the Grey Herons, birders go '...didn't know they nested there, how many pairs?'. And then have trouble computing the answer 'none'. Such roosts are simply not on the radar of many birders.

'Club Loser' will be closed down by the end of the month. Perhaps this roost behaviour, at its start, is similar to something seen in many other colonial species- recognisably immature birds aren't really wanted in the heart of a colony. Perhaps at its end, those adult breeders who drove them off are way too busy providing food for their young to waste time bossing the immatures about. No need to play 'who's the daddy?' now the eggs have hatched.

The old text of 'Birds of the Western Palearctic' hints at limited information on nocturnal roosting but goes on to say that youngsters roost close to the colony throughout the year. The main local colony here is, of course, Northward Hill, the UK's largest. As the Crow flies, some six miles away. The crow's route suits the Herons perfectly throughout most of the year. The estuary is only really beginning to close at Pinup Reach, but has the western island complex scattered around it, and many non-waterbirds choose to cross in this area rather than over more open waters. Of course, the yellow line on the map below is only representative, birds in transit being more widespread than shown, but you get the idea.

The two spurs marked show routes less often used to join that flyway. Interestingly, used more times for 'returning' towards Hoo and Northward Hill than leaving. To me, that implies the birds may well be spreading east during the course of a day, away from the concrete of the Medway Towns, checking a series of feeding areas as they go, before returning direct. Studies have shown adults not only know the better spots, they also know the best times to be there. Youngsters might spend a big part of their hunting time staking out one good spot, not yet appreciating the subtle skills of the seasoned angler. Which might be another appeal for Berengrave- as well escape from all that harassment, somewhere a lot closer to what remains of the southside marshes off to the east.

It also knocks holes in the 'migrating Herons' cognitive bias I suffer when lines of mainly young birds cross Pinup on an early autumn morning.
"Hey, you at the back, you all migrating?"
"Nah, just hungry, that one in front found something yesterday, just following him."

All highly fanciful thinking of course, from my mantra of 'not all movement is migration'. But dreaming about Herons helps pass the time counting the Magpie roost right now. Those numbers are in freefall with their own nesting underway. Couples are coming in together though, feeling safer at the old communal roost than risking a night in a still egg-less nest. But of course there's quite a few single Magpies turning up. Quite a few. 'Club Loser' is open to all, 365 nights a year.

A ring from middle estuary- #1293502

I trained as a ringer under my good friend Bill Jones, often on Oakham Island. Although I now limit myself to the southern shore and Oakham is frustratingly just north of the main channel, mid-estuary, I hope publishing an occasional map from some of his ringing recoveries over the years here on this blog will be of interest.

Grey Heron Ring no.1293502
Ringed: 12th February 2003
Found: 16th May 2008, Töcksfors, Varmland, Sweden.
Freshly dead- found in a fishing net.
Found 1,920 days after ringing, 1,143 kilometres from Oakham.

To date, this is the only British-ringed Grey Heron to have been recovered in Sweden. The bird was most likely not actually British, as foreign-ring recoveries have shown birds from north and east Europe routinely overwinter in the UK.

More details of Grey Heron ring recoveries (plus a map of international movements) can be found c/o the BTO website here.

It all kicks off

Berengrave

23:59, New Year's Eve. I'm standing in Berengrave LNR at the viewpoint over the flooded chalkpit quarry. The odd Magpie and Woodpigeon are giving unsettled calls around me. Fireworks have been going off intermittently for the past five hours, and it is clear quite a few birds have already shifted out from their main roosts over the deeper water to the chalkpit edges. The annual  New Year's celebrations are something that causes a great deal of disturbance to birds, and the 250 or so Magpie and 550-odd Woodpigeon calling the LNR home were about to experience fireworks 'shock and awe'.

00:00. It all kicks off. Woodpigeon start to crash out of the trees around me, hurrying away. In contrast, the magpies go quiet as they pass low over me. Strangely, no sound of passerines. It might be many have moved on the earlier explosions. Their roost numbers have also dropped away in recent years, and so if they do not alarm, you may well miss them. Instead, Lapwing can now be heard overhead, moving inland from the estuary- the annual mass disturbance is now well underway. 

Lower Halstow wharf and church

I've had an interest in this event since the Millenium, when I was witness to a large disturbance over the mouth of the Medway, from Sheerness to Grain, as masses of winter thrushes fled the huge bombardment. Then my years at Rye had proved disturbance flights a given. The large organised display lights up the surrounding marshlands, and I used to record wildfowl fleeing Castle Water heading for the Tillingham valley, with big numbers of passerines, flighting in all directions.

Tonight's big rush was over. I moved down to Motney Hill to try to gauge events there. The flats were pretty much vacant. One or two Teal called, and several lost Dunlin alarmed overhead. A handful of Brent circled the Hill.

Twinney

The waders and wildfowl clearly hadn't enjoyed the experience. I had mused whether they simply head for the main channel where They might feel safer but, then again, several fireworks displays were still in full swing over the Hoo skyline With such a level of disturbance, where would these birds feel safe?

On to Lower Halstow. 01:15. Again, many fewer sounds of life than expected from the creeks, and for a while I was more focused on the squabbling Little Owl with birds on Great Barksore, in the Brickfields and along by Frog Farm all squabbling with each other. Then the call of Dunlin overhead reminded me why I was out. These birds were going inland, high. A distant Grey Heron called from the direction of Ham Green, continuing south and heading off towards Callum Hill.

By the time I reached Funton, the disturbance seemed to be all over. Though the tide was making, little could be picked out. I headed home for rest at 02:00.

Later that day I was pleased to receive a timely retweet linking to a Dutch paper on the subject of fireworks. Clearly there is a lot of real disturbance happening, and the paper hints at a clearly observable level of fatalities. As more birders become aware of this issue, will they start to make the noise? Only time will tell. I take some hope from seeing just nine Chinese lanterns sail over the estuary during my two hours in the field. The message on their dangers seems to be getting through.