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.

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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.

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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.

Goldcrest Poll Results

If you follow me on Facebook or Twitter you may have spotted a little quiz where you got to decide which of the spectrograms below is a real Goldcrest.

Twitter Results

Facebook Result

Well, the results were pretty unanimous on both Twitter and Facebook. The majority of people thought that B was the real Goldcrest. Well I’m quite happy with that result, as the answer was in fact A !!!

So far I’m yet to find a Firecrest that’s been able to produce the Goldcrest song with 4 notes per phrase. It’s the last note of each phrase that appears to be the most challenging for the Firecrest.

I’ll leave you with a picture of a lovely Froglet, one of many covering the woodland flower at the moment that’s plastered with Bluebells. It’s going to be a good season by the looks.

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

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