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Fertility Control for Grey Squirrels : what do the next 5 years look like?

Giovanna Massei National Wildlife Management Centre APHA

RSST, UK Squirrel Accord and Royal Forestry Society Sand Hutton, 19 October 2017

Conflitti uomo-fauna selvatica

Road traffic accidents

Impact on native species

Disease transmission

Livestock predation

Damage to crops, forestry, property

Human-wildlife conflicts are increasing

Methods to mitigate human-wildlife conflicts

poisoning shooting trapping

Lethal methods

fertility control

exclusion

behaviour modification

diversionary feeding

Non-lethal methods

translocation

Novel immuno-contraceptives

GonaCon

Gonadotrophin Releasing Hormone vaccine

“single-dose” injectable vaccines from our US partners

Vaccines inducing antibodies against proteins or hormones essential for reproduction

75-100% animals infertile for 2-8 years

Credible practical applications

BUT animals must be captured

we need an oral contraceptive

Fertility control applications via injectable vaccine

Wild boar: 1 dose GonaCon stopped reproduction in 92% sows for 5-8 years

Feral goats: 1 dose GonaCon reduced fertility by 83-92% for > 4 years

California ground squirrels: 1 dose GonaCon reduced the % of lactating females by 91% (year 1) and 96% (year 2)

Developing and delivering oral contraceptives to

control populations of grey squirrels

The project

5 years 1 M £ 4 research groups: UK x2 France USA

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Ye

ar 1

Ye

ar 2

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+ 4

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ar 5

The project

Test novel contraceptive formulations (lab rats) Design systems to monitor feeding patterns by squirrels (lab + field) Start breeding colony of squirrels

Test contraceptive doses, frequency, bait type (lab rats) Optimise bait uptake by squirrels (field)

Test effectiveness of contraceptive in squirrels (lab) Optimise bait uptake by squirrels in different contexts (urban,rural) Liaise with regulatory authorities to assemble registration package Refine model on integrated methods to reduce squirrel numbers

Pilot trials with contraceptives on squirrel populations Initiate trials for registration package

The APHA team

Project leader

1 statistician

Field studies coordinator

Lab studies coordinator

2 lab technicians 2 modellers

4 field ecologists 2 lab ecologists

Biology, behaviour, population dynamics Oral immuno-contraceptive vaccine targeting GnRH

60% rats fed the contraceptive did not breed

(control rats: 10-30%)

Rats fed the contraceptive in a bait showed reduced response to the

vaccine: fewer rats responded and had lower antibodies to the vaccine

Novel formulation needed for oral vaccine to increase immune response

APHA and collaborators developed

novel GnRH-based oral vaccine

Novel formulation to deliver an oral immuno-contraceptive

Spores and pollen grains

Pollen/spores are natural and renewable

Commercially available

Genetic material removed to obtain sporopollenin exine

capsules (SpECs)

SpECs withstand stomach conditions

Proven effective delivery of drugs such as fats, oils, vitamins, enzymes, hormones, ibuprofen

SpECs for an oral contraceptive vaccine

Proven vaccine delivery in SpECs fed to mice

increased antibodies in mice

antibody response lasted for up to 7 months

SpECs move into mouse gut wall, thus offering :

a possible mechanism for oral vaccination

potential to maintain this response for at least a few months

Proposed work

Identify SpECs species

Trials with laboratory rats to test SpEC-encapsulated oral vaccine

Captive trial repeated on grey squirrels

Field pilot trials to confirm efficacy, % of the population treated

Large-scale trials to monitor effects at population level

Developing an oral contraceptive

Biology, behaviour, population dynamics

For contraceptives that are not target specific

Specificity through delivery

Grey squirrel specific hopper

Target species delivery

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Grey squirrel-specific hopper to deliver baits containing oral contraceptives

Target species delivery

Rhodamine B in whiskers of grey squirrels

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1. Model the effort required to reduce grey squirrel population size via culling, contraception or culling + contraception 2. Identify data to collect to improve the ability of the model to predict the impact of population control on squirrels’ number

Defra study January-March 2017: aims

Defra study January-March 2017: results

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Defra study January-March 2017: results

Culling with different levels of effort

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Defra study January-March 2017: results

Fertility control with different levels of efficacy

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Defra study January-March 2017: results

Culling in Year 1, followed by fertility control with different levels of efficacy

Proven GnRH-based contraception

Candidate oral contraceptive available

Delivery method available

Done

In progre

ss To d

o

Current and future work

Model impact of fertility control on population dynamics

Confirm effectiveness of contraceptives

Test bait uptake by % of grey squirrels

Manage public expectations

Captive and field trials Registration of drugs

Funding Public support Stakeholder engagement

Over-abundant wildlife

Non-native invasive species, incl. feral animals

To complement culling to control populations or

their economic / environmental impact

Where culling is illegal, unfeasible, undesirable

Oral contraceptives scalable to new species and contexts

Scalable applications for oral contraceptives

Oral contraceptives will be an important tool to manage wildlife

Raising public awareness on feasibility, cost, safety, sustainability of different methods will be key to successful management

In summary

With thanks to…

…the squirrel team!

Questions?

giovanna.massei@apha.gsi.gov.uk