Just a few hours!

This post was inspired by a recent email conversation with a fellow seawatcher, who thought looking at effort (hours put in) and the results was fascinating. To many it might be a yawn but I’ll continue!

As my seawatching became more and more regular, I made myself a relational database in ACCESS to capture the results (big yawn!). By relational this means a whole watch is a record, which captures date, the start and finish time, weather etc; while the bird sightings (or marine sightings) are sub-records attached to that day. This means I know how many hours I’ve watched and can calculate passage rates (birds/ hour), by Devon, by Devon site etc. Importantly it effectively records nil results by default, days where I’ve not seen a species (e.g. days with nil Balearic Shearwaters). These nil records are important for calculating effort, but cannot be calculated in many Bird societies’ databases because of the data structure (because the blank days aren't recorded). So to date (since 1991 when I started keeping records), I calculate I’ve done 3814 hours seawatching in Devon. That’s the boring bit over.

So out of interest I’ll pump out some figures from my database of numbers seen in those 3814 hours (Devon only), firstly for the tubenoses. So let’s go rarest first:

1 Macaronesian (Barolo) Shearwater (BBRC accepted)
2 Yelkouan Shearwaters (one BBRC accepted, one in circulation).
3 Fea’s Petrels (BBRC accepted, notice I’ve not put in the / Zino’s bit, more on this for another day).
50 ‘Blue’ Northern Fulmars
166 Leach’s Storm-petrels
544 Cory’s Shearwaters
689 Great Shearwaters
2049 Sooty Shearwaters
6110 European Storm-petrels
7842 Northern Fulmars
9981 Balearic Shearwaters
373413 Manx Shearwaters

One thing that surprised me was, I didn’t expect Leach’s to be rarer than the two big shearwaters, but when you think about where I watch it is - that’s likely to be different say in East Devon. Nothing else really surprising though. The ratio of Balearic to Manx Shearwaters is 1:37. Sooty to Manx is 1:182 and Sooty to Balearic roughly 1:5. Interesting how rare ‘Blue’ Fulmars are down here, roughly 1:157 to our usual phase birds.

'Big' seabird events very much skew the results, i.e. I’ve seen more than half my Devon Cory’s Shearwaters on just one day and even more notable, I saw 93% of the Leach’s total in a day. But my philosophy is, if you don’t put in the hours you're unlikely to be there when that ‘big day’ happens. Another thing coming out of this, considering the hours put in, I've got a very low hit rate with seeing rare tubenoses! While on rare seabirds notice that's roughly a 1:5000 chance of seeing a Yelkouan vs Balearic Shearwater (I don't count probables)!!

What about the skuas? Again rarest first:

97 Long-tailed Skuas
1079 Pomarine Skuas
3924 Great Skuas
5389 Arctic Skuas.

No surprises there either. That’s a 1:56 ratio Long-tailed to Arctic; and a 1:5 ratio Pomarine to Arctic. Sadly with the continued demise of the Arctic Skua population, these ratios will shorten further. Way back in 1998 I remember an incredible few days for Arctic Skua passage at Berry Head, when I personally saw 875 during 6–7/09/1998. I’m unlikely to ever see anything like that again and perhaps the days of a 100+ Arctics on a seawatch down here are gone. I predict the Great Skua to Arctic Skua ratio moving more towards 1:1 (currently 1:1.4) and may already be there!

And scarcer gulls, terns and auks - I’ll just do my favorites:
1 Laughing Gull
10 Roseate Terns
10 Black Guillemots
16 Little Terns
48 Sabine’s Gulls
65 Little Auks
261 Arctic Terns
274 Black Terns
602 Mediterranean Gulls
1273 Puffins
3891 Sandwich Terns
8306 Common Terns

Interesting? For me Roseate Tern is as rare as Black Guille on a seawatch, otherwise no surprises there.