The Ecology and Conservation of the Aspen hoverfly
The Ecology and Conservation of the Aspen hoverfly
The Ecology and Conservation of the Aspen hoverfly
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<strong>The</strong> <strong>Ecology</strong> <strong>and</strong> <strong>Conservation</strong><strong>of</strong> <strong>the</strong> <strong>Aspen</strong> <strong>hoverfly</strong>Hammerschmidtia ferrugineaEllie L. Ro<strong>the</strong>rayStrategic Development Fund
DistributionIn Britain, H. ferruginea has reduced from 15 to 8locations in Scotl<strong>and</strong> since <strong>the</strong> 1990s (<strong>the</strong> MallochSociety)H. ferruginea sitesPresence 2006Additional sitesAchany GlenDulsieKinveachyDulichtTorr AlvieInvertromieSpeybankSpeybridgeAchilityCreagan BruegachBoat <strong>of</strong> GartenDinnetInverfarigaigKinnordTomnagowanImages: http://earth.google.com
<strong>Ecology</strong>• Saproxylic <strong>hoverfly</strong> that depends on temporary<strong>and</strong> declining habitat- Fallen decaying aspen- Black sap flows- min 100 trees <strong>of</strong>min 75cm CBH• Correct condition- 12-15cm 15cm diameter- 7 to 12 months to decay- Can last 3 years• Larval stage- 1 to 2 years as larvae
HabitatManagement:<strong>Aspen</strong>• Introducing fallenaspen into <strong>the</strong> habitat• Leng<strong>the</strong>ning time <strong>of</strong>decaying stage
How many larvae can a fallen aspensupport?• Management currently involves cutting upfallen logs, thus it is important to know howmuch is required to maintain <strong>the</strong> population
Emergence traps <strong>and</strong> mark-recapturerecapture• Dispersal ability• Emergence <strong>and</strong> flight periods• Longevity• Behaviour• Adult food-plants
Results?Total emerged 2006: 339Total emerged 2008: 302
How many larvae can a fallen aspensupport?FallenaspenLength(cm)Circumference(cm)Surface Area(cm)TotalEmergenceAreaperinsect (cm 2 )log13200.55 to 1 larvae per 100cm 27223040231100log28060480022218log3165811336586155Total158(Sd. = 95.6)
<strong>The</strong> emergence period- 22 days (17th May until 6th June 2006)- 26 days (17th May until 16th June 2008)
Flight period120100No. individuals806040200May June JulyFlight Period (17th May until 15th July)Total emergence period: 17 th May until 16 th June (26 days)Flight period: 17 th May until 15 th July (60 days)
Longevity50454035Age (days)302520151050FemaleMaleMale maximum longevity: 32 daysFemale maximum longevity: 51 days
Re-sighting at decaying aspen
Territory 0Territory 1Territory 2Territory 3
Patrolling flight behaviour:long, tight ‘weave’Patrolling flight behaviour:short, wide ‘weave’
Novel age effect
Adult food plantsAnd…?Bird cherry Prunus padusRowan Sorbus aucupariaHawthorn Crataegus monogyna
Dispersal abilityHow far do adults disperse?KeyMixed <strong>Aspen</strong> Forest (33 hectares)Main areas <strong>of</strong> flowering plantskkNewly fallen or severed aspenDecaying Fallen <strong>Aspen</strong>NkkLog2Log1kkkkk kkLog31008mTromie logk
Preliminary conclusion• To manage cut aspen <strong>and</strong> ensure input many fallenlive trees can be used for sequential cutting butinsure protection but where possible leave whole• Include known adult food-plants in managementprescriptions• Fallen aspen may be used for future monitoring totest effects <strong>of</strong> current management• Dispersal distanceDispersal distance- if findings show greater capabilities <strong>the</strong>n small aspen st<strong>and</strong>s mayhold smaller meta-populations
Acknowledgments• Pete Moore, Carl Mitchell <strong>and</strong> <strong>the</strong> volunteers (RSPBInsh Marshes)• Iain MacGowan (SNH <strong>and</strong> <strong>the</strong> Malloch Society)• Jane Sears (RSPB)• Anne Elliot (SNH Achantoul)• Graham Holloway (University <strong>of</strong> Reading)
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