Saturday, 13 October 2012

Overnight migration monitoring 12th October2012

Ran the tape overnight again, on 12th October. Weather was fairly clear skies, with a SW wind, but with a band of rain passing thru.
Results were down on the previous weekend with only a handful of birds:

Redwing: 6
Song Thrush: 1

Present:
Tawny Owl, Robin

The biggest highlight was my new method of analysis:
I now produce a single mp3 (@  128kbps),
then split the file using a free tool called mp3splt.
Also, by loading the next sound file as I analyse each file reduces waiting time.
I'm up to 5 hours of analysis per hour now!


Thursday, 11 October 2012

Overnight Migration monitoring

I've noticed a few people are trying their hand at monitoring night migration lately. It seems to be popular in the US where software is available to pick out calls. See Oldbird.org.

So, with nothing to lose, I wrapped my Zoom H2N in a tight plastic bag, put the weathershield on and left it in the front garden overnight! The first problem I encountered was the size of the wav file the following morning. Can't remember how big it was, but it took audacity over half an hour to open it! Fortunately, the Zoom has a built in tool to divide files, and so I chopped the file into 1 hour chunks. These took about 5 minutes to open in Wavesurfer, and once the spectogram was focussed and showing a healthy glow of background noise it was fairly easy to fast forward/scroll through each hour segment.

Lots of unwanted noise at first, but it soon became clear that the vertical signals were fireworks, doors slamming, or twigs snapping. The huge blurred low frequency areas were cars, and yobs falling out of the local pub! I was starting to get a bit disheartened after listening to several dogs barking, and a distant car slam on it's brakes but then out of all the noise, the bird calls started to emerge in the recordings.. Local Tawny Owls came first, and were pretty distinctive after a while. The sonogram long drawn out, and just higher than the man made sounds of the village.

I continued fast forwarding wondering if this was the limit of my kit. You don't get much louder than a family of Tawnies, especially if they are in a tree pretty much above the microphone, but then a high frequency downward sloping call whizzed by. I rewound and played back.. REDWING! Success! This was followed by a handful of Redwings, then a Song Thrush which was even fainter on the tape, but the sonogram was clear as day. So, now I'm thinking, if it can pick up Redwings and Song Thrushes flying over, there probably isn't much that this set up would miss. Any Waders or Wildfowl would definately get picked up, Finches probably would if they went straight overhead.

A sample of results are below, plus the details of how they were obtained.

Overnight Migration monitoring, Hampshire, 6th-7th October 2012:

Redwing 24
Song Thrush 4
Present: Tawny Owl 2

Very faint Redwing:
Redwing Sonogram, Redwing flight call from night monitoring, 6th October 2012, Hampshire

Faint Song Thrush
Song Thrush sonogram, Song Thrush call overhead during night time migration monitoring, 6th October 2012, Hampshire


Very noisy Tawny Owl
Tawny Owl Sonogram, Tawny Owl Sonogram from night monitoring, 6th Oct 2012, Hampshire


Set up details:

Zoom H2N ext

Gain 10 (max)
file type mp3 / 96kbps
auto gain OFF, low cut filter OFF,
Recording mode: MS with very small side lobes

Analyis used Wavesurfer software
Samples extracted and uploaded to Soundcloud taken using Audacity software

Next time, I intend to use auto record, constantly triggering throughout the night. This will generate hundreds of small mp3 files which can be joined together using a single terminal command on the pc merging them into ~60 minute mp3 files for subsequent analysis.

2012 finally kicks in

* Self-Found Melodious Warbler finally brings 2012 to life!
* Other Migrants on Scillies include Yellow-Browed Warbler, Ring Ouzel and Pied Flycatcher
* Quiet Scillonian crossings still bring some good sightings

Took two weeks off work and headed to the Isles of Scilly for a few days. Unlike recent trips to Shetland, which I have had to book many months in advance, camping on the Scillies can be booked a day in advance, so I had no real excuses that the weather was all wrong! Having said that, a Low Pressure that I had intended to piggyback somehow doubled back on itself, and loitered in the Irish Sea for the duration of my stay. This caused North and North West winds throughout, and no doubt reduced the number of East Coast migrants continuing West.

I stayed on St.Agnes, and decided pretty early on that the outlying Isle of Gugh, joined to St.Agnes by a sandbank and cut off at high tide, was the place for me.

And so it proved to be a super venue with a Melodious Warbler found on the first morning making the trip a success for me (any new "self found" bird in the UK is a real highlight for me nowadays). The second day didn't quite match the first with a Yellow-Browed Warbler the stand out bird. There was a good number of Spotted Flycatchers throughout, and other highlights were Ring Ouzel, Pied Flycatcher, along with more common migrants like Whinchat and Yellow Wagtail. I say common, both where firsts for the year for me, but that probably reflects the relatively poor birding year I have had.

Other birds seen well, but found by others were Red-Breasted Flycatcher, Ortolan, and Little Stint, plus a single Greenshank.

Another highlight for me, of the Scillies is the ferry journey. The outward crossing despite the severe winds just days earlier was fairly quiet with just a single Great Skua, and Manx Shearwater the highlights. Kittiwake, Great Northern Diver, and Red Throated Diver being the other highlights. The return crossing was slightly better with a Balearic, and Sooty Shearwater plus 4 Harbour Porpoises.

Photos below:


Linnet, Scillies, Sept 2012 Spotted Flycatcher, Scillies, Sept 2012 Pied Flycatcher, Scillies, Sept 2012

Yellow-Browed Warbler, Scillies, Sept 2012 Yellow-Browed Warbler, Scillies, Sept 2012 Red-Breasted Flycatcher, Scillies, Sept 2012

Wren, Scillies, Sept 2012 Swallow, Scillies, Sept 2012 Song Thrush, Scillies, Sept 2012

Wheatear, Scillies, Sept 2012 House Sparrow, Scillies, Sept 2012 House Sparrow, Scillies, Sept 2012