Viewing entries tagged
Research

Shape Conforming

I hope you’re not getting tired of hearing about Nightjar but honestly I don’t care haha. Spending time with one species, learning more about their characteristics and behaviour is what I love and it’s the only way you’ll ever get a chance of photographing this species in the day. I’m now on my 4th pair and my 7th individual (yet to locate the female of the 4th pair). I find it interesting that each pair has chosen a different type of habitat, or at-least the same habitat at different stages.

  1. 3-4 Year Old clear-fell, mostly small-medium sized trees

  2. 1 year old clear-fell, only bracken, grass.

  3. 3 year old clear-fell, mostly grassland, bracken and heath

  4. 3 year old clear-fell, totally rocky habitat with bracken between.

It goes to show how versatile they are, so long as there is suitable habitat around them for moths, they’ll roost almost anywhere there’s suitable cover.
The pair that’s chosen the rocky habitat is the one that I’m most interested in, as he’s also choosing to roost on rocks, rather than logs/sticks. If you look closely, even the shape of his back appears to match the shape of the rock. I wonder if this is strategic? Shape conforming is common amongst species that rely on camouflage to survive and they do appear to match their chosen roost spot. If on the end of a log, they’ll sit tall, short, tail town as if they’re part of the end of that log. If they sit across a stick, they’ll sit in the same direction and flatten themselves out.

As a contrast, here’s the female of pair number 3 showing that typical flattened out pose that matches the long shape of a stick. I loved this chosen roost spot, but it’s doubtful she’ll use it again though as she looks ready to burst. I’m surprised she hasn’t laid yet. Maybe she has and her first clutch failed? I hope that isn’t the case.


I’ve also been studying their vocalisations but I’ve needed a few years worth of field recordings on Nightjar, in order to confirm a theory that you can identify individual males by their song. The way you would do this is to work out the average BPM, length of phrases and also the frequency of both exhale and inhale.
I’ve collected so far at-least 6 different males, though I’ve focused on returning to the same territory for the last 2 years in the hope to confirm it with one individual male. So far it looks like I can confirm this theory, as I’m finding only a 0.8 difference between the BPM recorded in 2017 to present day. A couple more years worth of recording Males and I should be able to give more weight to this theory.
The analysis is actually pretty easy and could even be done in the field so long as you had a laptop to return to. I’ll publish more details about my methods at the end of the season.

Nightjar Identification

Born from Destruction

I find it hard to explain just how much I love Nightjars but hopefully by the end of this blog you’ll understand why.

The title sounds a bit dramatic, and that’s because the Nightjar for me is much more than just a cool looking bird that makes an unworldly sound. This bird for me is a reminder that even in a world full of environmental destruction, there are animals out there that have adapted to an ever changing landscape.

The Nightjar has done just this, by using clear-felled woodland to their advantage, as the bare ground, twigs, logs and cut stumps make for a perfect place to blend in and a perfect place to breed. The regrowth of these (often upland) clear-fells bring all kinds of plants, from heather, foxgloves, bracken, broom, gorse and native broadleaf trees, all of which are great for moths and insects which the Nightjar specialising in eating on the wing during the night. In the night they eat and drink on the wing, opening their mouth wide like a Swift and skimming lakes, tree tops and low vegetation for food and drink.

Below is a picture of my first self found Nightjar but hopefully not the last of the season. I have 6 pairs between two locations that I’m keeping an eye on. I hope to record enough male songs to confirm a theory that you can identify males by their BPM. This is a female, so she won’t be using this roost every day, especially once she lays her eggs as she will then incubate on the ground never to be seen again as the ground is mostly dead bracken which she blends into even more! The male was close by. He’s never too far away during this period as he will watch guard over them both. I hope to locate the male later on in the year once they’ve officially began breeding as it’s still early days yet and he’s still copulating with her.

I’ve shared this recording before but it’s still the best one I’ve captured so far, with perfect weather conditions and capturing the song from beginning to end.

If it wasn’t for the new green growth of the green bracken, I don’t think I would have spotted her at all.

I hope to get more opportunities but the most important thing for me at this stage is to ensure I don’t disturb them breeding so I’m going to let them settle in and see how the season goes. I might also continue to look for the other 5 local pairs and may even explore some new clear-fells in the valley to see if they’re attracting Nightjar yet. Either way, it’s quite exciting to finally get time in the day with these birds as I’ve spent so much time watching them in the night, it’s nice to see them in full light.

Research

Steve Williams took this photo.. I’ve clearly been eating too much chocolate this easter haha.

It was great to meet up with Liam Olds, Steve Williams and Mike Kilner over easter. I aimed to show them my Violet Oil Beetle location and we weren’t disappointed with over 40+ individuals found. I’ve since found them a few miles away also on a road side verge. Proof that this valley has to be one of the largest strongholds for this species. We recorded 10 Species of Bee thanks to Liam Olds’ vast knowledge, including a Chocolate Mining Bee which was a first for me. It really is great to be surrounded by such knowledgeable naturalists, there’s so much knowledge to obtain about the natural world, I wish I could soak it all up faster! Everything I know, I’ve learned from other people, or by myself through personal discovery and research. It goes to show that if you’re passionate about something, you learn much faster. This is why most people struggle with their current Jobs as you really need passion to drive you forward. I know I’m currently struggle with Jobs, being out of work since October, but I do believe I’m heading in the right direction, to obtain a Job that will give me a sense of purpose, which is after-all what we all want in life.


Here are a few pics from easter. I’ve spent more time out with the recording gear really so haven’t got too many images but I did have some good moments - My first Wood Warbler of the year, a showy Sedge Warbler and my favourites were actually the bugs, Black-spotted Longhorn Beetle and those cute glaring eyes of the Jumping Spider (evarcha falcata). I did go down to see Blair Jones’ Red-necked Phalarope at Goldcliff which has been proving to be a great birding spot this spring, with Black Kite, Spotted Redshank, Curlew Sandpiper, Grey Plover and all the usual supporting cast. While it does tick a few boxes for me, I’m not sure ticking boxes is really my thing. I’ve never made a year list, local list or life list of any kind, I just want to experience nature and take whatever opportunity nature decides to throw at me.


Firecrest Update

If you haven’t been following, I’m studying mimicking behaviour in Firecrest this year and so far, 3 out of 3 males on territory have been able to produce a goldcrest mimic to varying degrees.
The original bird discovered is still by far the best at mimicking goldcrest which is probably why it stood out to me so well to begin with, but the others have used mimicry in a more subtle way.

Not only was the original Firecrest better at the mimic, but it also used it way more often. This could be because there aren’t any other Firecrests in its territory, so why waste time singing Firecrest? Note in the spectagram that it’s producing 3 notes per peak and with the iconic ‘trill’ at the end. Over-all producing 29 notes including trill.

Firecrest No.1 Mimic


Firecrest No.2 only used the odd mimic within a single song and while it still produced 3 notes per beat, the end ‘trill’ is reduced to only 2 notes, notes of which are more typically expected at the end of the Firecrest song. On average the bird produced 16 notes including the trill at the end. It’s worth saying that the amount of beats doesn’t matter too much as even a real goldcrest song this can vary, however so far the birds who sing less notes and also singing a less perfect rendition of the goldcrest song which is why I’m documenting them.

Firecrest No.2

Firecrest No.3 is by far the most interesting bird, largely because of the circumstances in which it used the mimic, doing so directly after hearing a distant goldcrest singing inside its territory, this can be picked up on during the recording. It only lets out one burst of mimic, which is so simplified it hardly meets the requirements of mimicking but it does have the overall structure. Rather than 3 beats, it has just 2 and this bird neglected the trill at the end entirely. Again, this isn’t going to be a completely controlled study as even goldcrest vary, but it’s interesting to hear these mimics used naturally at a time of year where territories are being established and a birds song is never more imperative than in early spring.

Firecrest No.3

It’s worth noting also that the tempo for each bird also varies;

  1. 154bpm (Sang 12 or more times)

  2. 182bpm (Sang 2 times)

  3. 184bpm (Sang 1 time)

This could be nothing but the bird with the most accurate mimic does sing the phrase the slowest and the bird with the less accurate depiction sings the phrases the fastest. More recordings over the breeding season should reveal whether any of these observations are a coincidence or not but it’s all being documented included frequency of notes.

The reason I’m doing this is because I’d like to know just how accurate these mimics are and I’ll compare all my recordings this year side by side with real Goldcrest songs so that by the end of the study, we’ll hopefully be able to trust our ears again when listening out for Firecrest in the field.

So far I’m noticing that the Goldcrests sound is a little ‘thinner’ with less overall weight to it but that might not be enough to go by, on its own.

Mimicking Birds

By now you’ll realise that I’m quite interested in mimicking birds, having done talks to the Welsh Ornithological Society and studied them during my sound degree in University.  Mimicking species aren’t always easy to find however,  because sometimes they mimic so well, that you assume they are the species they are mimicking and don’t care to look twice. This was evident in my recent discovery, where a friend of mine found a new Firecrest territory, just a mile from one that I found last year. Upon visiting the territory myself, I noticed something a bit odd about the Male Firecrests song.. It didn’t sound like the long-drawn out-monotone notes that I expect to hear in their typical song.. and if that wasn’t enough to raise suspicion, it then let out 3-4 phrases of GOLDCREST song! :O

The bird didn’t appear to show signs of hybridisation, with all the standard Firecrest features intact, so I instantly contact around to see if anybody else had heard or read about mimicking Firecrest before. Nobody had heard of this behaviour and after some research on the web and thru books, I couldn’t find any documentation on this. That was until I contacted Chris Hatch, who said that he would look into it for me. Chris later rang me after finding some information in one of his volumes of the ‘birds of the western palearctic’ which did note that Firecrest was able to produce both Firecrest and Goldcrest vocalisations but this was only on rare occasions. I mean it makes sense, especially in Gwent where the population is so high for Goldcrest. Despite them being able to live alongside each-other, they do still compete for the same food so it is within the best interest of the Firecrest to keep Goldcrests out of its territory. This could be the reason why it’s mimicking, but being such a similar species, who knows. There is a documented case in 1974 where a Male Firecrest was seen tending to a Female Goldcrests nest, from which fledged at-least 5 chicks. Document Link.

There are a couple scenarios that I can think of that would result in this Identity Crisis, especially in species that are so similar, but more research is needed. Luckily I have good friends, and providing everything goes well on NRW’s end, I’ll be able to study this subject bird under license this season. Below is a video showing a distant pic of the subject bird and a recording of the longest bout of Goldcrest song it produced. Hearing the recording alone, I think most people would struggle to pic out any differences. Looking closely at the spectogram, there are some minor differences but I’ll study that in more detail once the license comes thru.

Below is my first recording of the subject mimicking bird, starting off half singing / calling and changing to the goldcrest song at 1:30 seconds.

If you’re unsure of the differences between a Firecrest and Goldcrest song, below is a recording I did 2 years ago of both species singing in the same tree. I’ve noted in the comments where the Firecrest phrases are.

I only managed a couple of distant pics of the subject bird but as you can see in the photo below, the features are pretty concrete. The white supercilium is strong, with a clear black line thru the eye and a bright vibrant green back that appears more vibrant in the sun. The only feature that I have a question mark on is the apparent short legs. I’m not sure if it’s a documented feature difference between the two species, but through my own observations, I’ve always found Firecrest to hold themselves a little higher from the perch, giving the appearance of longer legs. I didn’t see that in this subject, but that could be nothing.

Mimicking Firecrest | March 2019

Mimicking Firecrest | March 2019

Should everything go to plan with NRW, I’ll keep you informed throughout the breeding season.