The Monarch Monitoring Project is a long-term study on monarch migration through Cape May, NJ. It is a part of the New Jersey Audubon Research Department, and closely affiliated with the Cape May Bird Observatory.

Tuesday, October 2, 2018

Update 10/2/18

Monarch numbers around Cape May Point seemed to drop gradually over the last few days.  Monday, late in the afternoon, I was netting a few monarchs to tag and many had already been tagged by another member of our team.  The fat measurement on most was high, suggesting they had been feeding, not traveling, over the last few days.  It seems that many other monarchs had crossed Delaware Bay and continued on their southbound migrations.

Tuesday afternoon, however, I netted several monarchs and most had little or no fat reserve, suggesting that they had been traveling.  This hints at the beginning of another movement of monarchs into Cape May.  We also learned that big numbers of monarchs were seen today at East Point, about 30 miles to our north and another location where migrating monarchs often concentrate.  Typically we have 4 to 6 distinct surges of migrant monarchs into Cape May each fall, so another build-up of numbers is expected.  We're hoping that numbers will increase over the next few days, but we never really know what's going to happen.

The discovery of monarchs tagged by someone other than our team is always unexpected, and we're delighted when it happens.  Sometimes the tagger came to Cape May -- that's why we ask all visiting taggers to share their tag numbers with us -- but sometimes they come from far away.  Today such a monarch was found, bearing tag code XYW 162.  We hope to learn soon the details of this tagging -- when and where it was tagged.


Most of the monarchs that I saw today, as has been true for many monarchs over the last few days, were nectaring on the flowers of groundsel-tree, Baccharis halimifolia.  This native shrub is widespread around Cape May and other coastal areas in the east, and it attracts monarchs and many other insects when it's in bloom (see below).


Unfortunately, the bloom period for groundsel-tree is brief, usually just for a week or less.  It won't be long before these blossoms are finished for the year.  Fortunately, just as its bloom period finishes, the next great nectar source becomes available.  Seaside goldenrod is abundant along the dunes and nearby patches of sandy soil around Cape May Point.  While most of the seaside goldenrod is still in bud, the first few flowers have opened up and the rest should come into bloom within the next few days.  For most of the month of October these flowers will be providing nectar for migrating monarchs.

Seaside goldenrod in bud (left)
and beginning to bloom (above).


We hope that we'll see many visitors coming to Cape May over the next few weeks, and we hope that there will be plenty of monarchs for those visitors to enjoy.  Watch for other butterflies while you're here, perhaps you'll see a gray hairstreak, a common buckeye (they're exceptionally common this fall), or the scarce long-tailed skipper.  There's always plenty to see on a visit to Cape May.

Gray hairstreak

Common buckeye
Long-tailed skipper







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