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Monarch Migration at Long Point, Ontario Tara L. Crewe

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Monarch Migration at Long Point, Ontario

Tara L. Crewe

Long Point Bird ObservatoryMonarch Migration Monitoring

Breakwater Tip

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Temperature (Degrees Celcius)

Mean #

Monarc

hs

(± S

td.

Err

)

Long Point Bird ObservatoryMonarch Migration Monitoring

Long Point Bird ObservatoryMonarch Migration Monitoring

Monarch counts highest during south-west headwinds, with Beaufort wind speed 2-3 (8-16 km/hour)

Long Point Bird ObservatoryMonarch Migration Monitoring

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9008

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Ave

rage

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on

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Date

Breakwater

Tip

Long Point Bird ObservatoryMonarch Tagging (2008-2009)

Question:

Is the number of monarchs stopping over, and length of stop-over, related to:

1. Site (tip vs. breakwater), 2. Habitat (nectaring plant

abundance)3. Monarch health (how fat?)4. Weather conditions5. Date

• Improve population estimates• Develop criteria to assess importance of stop-over sites• Develop guidelines for designation of “critical habitat”

• Tagged 1420 in 2008, 1712 in 2009• Recaptured 11% in 2008, 6% in 2009 (1 day - 2 wks)• More males caught early in season• Healthier monarchs caught later in season

2008: Stop-over Duration

Wind Direction

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p-o

ver

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tion (

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Headwind Tailwind

Wind Speed

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Days)

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Light Strong

Fat/Newly Emerged Skinny/Old

Fat monarchs stayed longerEffect of wind speed/direction not statistically significant

Recapture rate constant

2009: Recapture Rate

• Stop-over duration constant (mean 1.7 days)

• Recapture rate varied with condition:• Fat/Newly emerged butterflies were re-captured less frequently (2.6%) than skinny/old butterflies (9%)

No effect of habitat on stopover durationmonarchs did not stay longer at Tip: suggests flower abundance affects how many stop, but

not how long.

No effect of date on stopover durationmonarchs aren’t staying longer when breeding

still occurring (late August)

Year

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Annual Population Estimates (1995-2009)

Thanks to all the dedicated Long Point Bird Observatory staff and volunteers

Long Point Bird ObservatoryMonarch Migration Monitoring

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20Long Point Mexico

Annual In

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