Meet B037

Meet B037, or 1446262 as I affectionately know him (1446262 is his BTO ring number)!

B037 in 2016. Photo Jude Lane

B037 was first ringed and GPS tracked in 2010. Although we tracked some immature gannets last year, prior to that all tracking had been of breeding adults as they are far easier to re-catch and remove data loggers from. As gannets don’t breed until they are at least 5 years of age we know that B037 was at least 5 years old in 2010.

Last year he was breeding again so we GPS tracked him for a second time. We also gathered flight height data from him. As you can see from the photo above, he’s back at the colony again this year although sadly it looks as though his breeding attempt has failed.

Tracking the same bird in multiple years is really exciting. The data gathered from the trips can tell us how repeatable individuals are in their foraging behaviour and allows us to compare their behaviour with others in the colony. We can also look at how behaviour can be affected by weather conditions and other environmental variables in different years.

Here you can see the tracks of B037’s foraging trips in 2010 (pink) and 2015 (blue).

Foraging trips made by B037 in 2010 (pink) and 2015 (blue)

 

We recorded 3 trips from him in 2010 and 8 in 2015. His trip durations were slightly longer in 2010 (25 hours average) than in 2015 (23 hours average). Corresponding with that, he covered a greater distance on each trip in 2010 (538 km average) than in 2015 (470 km average).

So this part of the data I am gathering and analysing again this year (I’ll blog more on flight height later in the summer). Hopefully I’ll be able to tag some of the birds I tracked last year so that I can see how consistent they are in how high they fly as well as seeing if they are going to the same places.

It’s all about the Z’s and the W’s

In humans it is the combination of X and Y chromosomes that determine sex; females have two of the same sex chromosomes, XX, and males have two distinct sex chromosomes, XY. In birds it is Z and W chromosomes which determine sex but with the assignment the other way round to humans, females contain ZW sex chromosomes and males contain ZZ. It is the presence of these Z and W chromosomes in breast feathers, collected last summer, which I have been trying to determine these last few weeks at the NBAF Facility in Sheffield.

Working in a lab is a completely new experience for me and the complete antithesis of working on Bass Rock. The lab, as you would expect, is spotlessly clean, tidy, calm and quiet. Bass is noisy, smelly, dirty (filthy if it’s been raining) and a little bit crazy!

These two work environments could not be more different from each other

 

The process to get from feather to sex probably takes 3-4 days and involves 4 stages which I’ll attempt to outline below.

Firstly the DNA needs to be extracted from the feather. The end of the feather, or quill, which was attached to the bird, needs to be cut off and cut into tiny fragments. Working with small breast feathers requires a modicum of patience as small fragments of feather have a frustrating habit of pinging off if you fail to hold them down adequately!

Ready to start prepping the feather for DNA extraction

Lots of concentration required

Preparing feathers for DNA extraction.

A process involving the use of ammonia acetate is then carried out to leave you with a miniscule (so small you can’t see it with the naked eye) pellet of DNA in the bottom of a 1.5ml tube. To be able to assess and use the DNA it needs to be in liquid form and so is then dissolved in a buffer solution. There is a substantial difference in the quantity of DNA that you can extract from feathers and bird blood. This is because bird blood is nucleated and so contains much more DNA. The photo below of two 1.5ml tubes shows the difference.

DNA from a feather (left) and blood (right) – click on the photo for a closer look

 

The quantity of DNA in the sample can then be assessed using an agarose gel.

Output from an agarose gel

 

The next step is to run a PCR , or polymerase chain reaction, on the sample to see if it contains two identical Z alleles (male) or a Z and W allele (female). The Z and W alleles differ in size and this allows us to distinguish between them. A primer set that targets the Z/W alleles and an enzyme (Taq DNA polymerase) are added to the sample followed by a process of heating and cooling to three different temperatures. This allows the Z or W alleles to be identified and replicated millions of times. The Z and W alleles are then separated based on size using a DNA Analyser. The use of PCR in this technique means that even with a very small quantity of starting DNA, you can still get a sexing result.

The PCR machine with samples loaded

 

Then it’s time for the exciting bit, it’s time to put the samples into the DNA Analyser and see whether my pipetting skills have been up to scratch and if ZZ or ZW alleles have been identified from the samples.

So after much pipetting and spinning down I have managed to successfully  sex all 40 of the birds tested, which is a third of the birds we tagged last summer. That might not sound very many but I’m quite pleased with how it’s gone especially given how much more difficult it is to extract DNA from feathers than blood. Apparently mouth swabs are also pretty reliable but we’ll have to see whether we’re brave enough to get any of those!

Would you be brave enough to take a mouth swab? Photo credit: Jana Jeglinski

 

Finally I’d just like to say a huge thank you to Gavin Horsburgh and Deborah Dawson at the NBAF Facility (NERC Biomolecular Analysis Facility) who have both been incredibly patient with me and taken me through every step. Hopefully when I go back next year I’ll be a little more self-sufficient now I know what’s in store!

 

 

 

Who’s the daddy?

As you may have noticed the gannet research blog has been quiet over the last 6 months … the gannets left the colony at the end of the summer and I returned to Leeds to make a start analysing some of the data we collected. Until now there hasn’t really been too much to blog about, my days have mostly been filled with the joy and frustration of learning how to use a piece of very useful open source software called R which is integral for my analysis. However, for the last few weeks I’ve been enjoying a change of scenery working at the University of Sheffield.

What am I doing in Sheffield? Well, with another few months before I can get back out on the Bass to work with the gannets, I’m spending some time at the NERC (Natural Environment Research Council) Biomolecular Analysis Facility establishing whether the birds we tagged last summer were male or female.

Despite the fact that gannets, like many seabirds, are a monomorphic species (by this I mean male and females look identical) differences in their foraging behaviour have been discovered. Researchers from the University of Exeter found that male gannets from the Grassholm colony are more likely to forage off fisheries discards than females, whilst a recent paper published on the Bass Rock gannets demonstrated that female gannets make longer (in time and distance) foraging trips than males and that they are more likely to be associated with tidal mixing fronts. This is fascinating stuff but we don’t know the reason for these differences, especially considering the two genders are so physically similar.

Who’s the daddy? Male and female gannets are virtually identical in plumage and morphology

 

So given that males and females look identical, how is it that we are able to undertake these sex based comparisons? Work by a number of authors in the 60’s, 70’s and 80’s suggested that the sexes could be told apart through a number of subtle morphological and behavioural differences. These included the colour of the head plumage, the colour of the web-lines on the foot, the collection of nest material and a behaviour known as nape-biting.

Web-lines on the feet tend towards deep turquoise-green in females and lime-green or yellow in males

Head plumage can change from deep yellow to pale yellow during the breeding season in females

 

Collection of nesting material is carried out mainly by males but females can also join in

 

In 2000, these criteria were evaluated alongside DNA profiling from blood samples. The results of over 500 hours of observations at each nest found the only reliable non-molecular method for sex determination is nape-biting. It is only the males which will display this behaviour. You can find the paper here if you’d like to read more about what they did.

A male nape-biting his female partner on his return from a foraging trip. It is only males who display this behaviour. Photo credit: Sam Hobson

 

So we can reliably tell males and females apart by observing nape-biting. The only down side to this is that it only occurs when there is a change over at the nest. With foraging trips averaging around 24 hours in length you would have to live on Bass all summer in order to have a chance of observing this at every nest you are monitoring. This is why I am now in the Molecular Ecology lab in Sheffield learning how to determine sex using a DNA-based method.

If you’re interested, my next post will give you a bit more detail about the how we go about doing this.