Why Study hihi sperm?

Measuring the speediness of bird sperm might seem like an odd thing to do, but for Dr Helen Taylor, it's an important part of conservation research.

Are NZ's birds firing blanks?

 

Helen's work focuses on what happens to wild populations when they get very small. Unfortunately, due to habitat loss and introduced mammalian predators, many of New Zealand's native species provide good examples of this.

Small populations typically have less genetic variation (making them vulnerable to disease and other environmental challenges) and higher incidences of inbreeding (mating between relatives). Inbreeding can lead to all sorts of problems, including issues with reproduction and survival. In mammals, plants and insects, inbreeding is known to cause poor male fertility - inbred males are more likely to fire blanks! But no one knows if this is also true for birds. 

This is an important question in New Zealand. Many of the country's birds that have suffered population declines also show poor hatching success - is this caused by poor male fertility?

Enter, the mobile sperm lab

Helens Mobile sperm lab Image credit Helen Taylor

Helen’s sperm lab in the field
(Image credit: Helen Taylor)

Collecting bird sperm and analysing its swimming speed in the wild is no mean feat. Everything has to be done in the remote  locations where the birds live and swimming speed has to be measured as soon as possible after the sperm sample is collected or the sperm will die. Luckily, Helen has a few tricks up her sleeve:

How to collect sperm from birds

It's a weird job, but someone's got to do it... Males in most bird species don't have a penis, but instead have a hole called a cloaca, which is used for both poo and semen. During mating season, the area around the male cloaca becomes swollen. By gently massaging the swollen cloaca, Helen can cause some semen to pool on the surface and collect it using a tiny capillary tube.

How to keep the sperm warm

Sperm are sensitive little chaps. Too cold, they die. Too hot, they die. Dead sperm don't swim, so Helen has to keep the semen samples at a constant temperature. Anything that's going to touch the semen (e.g., pipette tips, microscope slides etc...) are kept on a reptile heat pad in a tupperware box. The microscope Helen uses to film the sperm has a special heated stage for the slide to sit on. Finally, Helen has a special sample tube organiser that she keeps in her bra, allowing the semen samples to stay close to her skin where they will be warm.

Hihi sperm x400 Image credit Helen Taylor

Hihi sperm under the microscope x400
magnification. ( Image credit: Helen Taylor)

How to measure sperm swimming speed

As well as the temperature control gear, Helen's mobile sperm lab contains a microscope with a camera fitted to it. The camera connects to a laptop and sends short (1 second) videos of the sperm to a program on the computer. This program measures the swimming speed of every single sperm cell in the video, allowing Helen to calculate an average sperm speed for each male. It's this number that will decide the winner of the Great Hihi Sperm Race.

Helen's sperm lab runs off a small portable generator, allowing her to take it pretty much wherever the birds are. This year, Helen took the sperm lab to Hauturu, Tiritiri Matangi, Bushy Park, and Zealandia to measure hihi sperm swimming speed. Next year, she's headed out to Queen Charlotte Sound to measure sperm swimming speed in South Island robins, plus revisiting the hihi on Tiritiri Matangi. Helen's research is funded by a three year Marsden Fast Start grant. You can follow her adventures on twitterinstagram, and on her website.