Action Synopsis: Bird Conservation About Actions

Freeze semen for use in artificial insemination

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • A small controlled trial in the USA found that using frozen semen for artificial insemination resulted in lower fertility in falcons, and a second small trial from the USA found that an American kestrel Falco sparverius had only 33% fertility when inseminated with frozen semen.
  • A small trial from the USA found that fertility rates were highest when semen contained 10% dimethyl sulphoxide (DMSO, a cryoprotectant), compared to semen containing 6% or 8% DMSO.


About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A small ex situ study (Parks et al. 1986) found that a single American kestrel Falco sparverius inseminated with frozen peregrine falcon F. peregrinus semen (defrosted and dialyzed to remove glycerol added before freezing) laid six eggs of which two were fertile and one hatched.

    Study and other actions tested
  2. A small, controlled ex situ study in New York, USA, in 1986 (Parks & Hardaswick 1987) found that four female prairie falcons Falco mexicanus and one American kestrel F. sparverius had significantly lower fertility when inseminated with frozen sperm (defrosted and dialyzed to remove glycerol added before freezing), compared to two prairie falcons and one kestrel inseminated with fresh semen (25% of 28 eggs for frozen vs. 94% of 17 eggs for fresh semen). Only two prairie falcons and the kestrel produced any fertile eggs from frozen semen. The birds inseminated with fresh sperm were a subset of the larger group and were inseminated with semen from a peregrine falcon F. peregrinus and a peregrine-gyrfalcon F. rusticolus hybrid. Frozen semen preparation took approximately 90 minutes after thawing, during which it was kept at 0-4oC. Insemination used 80 µl (frozen) or 20-70 µl (fresh) semen.

    Study and other actions tested
  3. A small ex situ study in 1983-5 (Gee et al. 1993) found that six American kestrels Falco sparverius inseminated with previously-frozen semen produced 14 infertile eggs only when the semen contained 4% dimethyl sulphoxide (DMSO). This compared with 35% of 17 eggs being fertile when 6% DMSO was used; 40% of ten eggs for 8% DMSO and 57% of seven eggs for 10% DMSO. Sperm mobility in semen containing 10% DMSO was lower (44%) than in semen containing 8% or 6% DMSO (61% and 62% respectively). Semen was taken from 15 male kestrels and frozen for between one and 14 months prior to thawing and insemination.

    Study and other actions tested
Please cite as:

Williams, D.R., Child, M.F., Dicks, L.V., Ockendon, N., Pople, R.G., Showler, D.A., Walsh, J.C., zu Ermgassen, E.K.H.J. & Sutherland, W.J. (2020) Bird Conservation. Pages 137-281 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.


Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

Bird Conservation

This Action forms part of the Action Synopsis:

Bird Conservation
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust