Monday, December 29, 2014

Monarch Butterflies Weathering California Storms

As 2014 is ending, another storm looms along the Pacific coast setting its aim on California and the southwest. In early December we visited several of the monarch butterfly overwintering sites along the coast and had the unique experience of watching how monarch butterflies respond to strong winds, heavy rains and coastal flooding. We were able to witness how adaptable and resilient monarchs are in their response to challenging weather conditions.

We arrived at the Oceano Campground in Pismo Beach at 2 p.m. on December 10. After setting up camp we quickly drove to see the overwintering monarch population before dark at the Pismo Beach Monarch Butterfly Grove just north of the campground on Highway 1. A major winter storm was arriving the following day with high winds and heavy rains in the forecast.The recently completed Thanksgiving Count for this site reported a total of 30,000 monarchs this year and we were hoping to see the normal distribution of monarchs at this location before the high winds began the following day.

Monarchs were located inside the circle of eucalyptus and cypress trees in the grove, densest on branches that would receive limited afternoon sun through a southerly opening. Their greatest numbers were directly north of the opening in a protected tree canopy and on a large branch on the south stretching over the walkway. A few fluttered nearby but most were already in clusters or tucked densely as singletons in nearby trees.

We also learned from docents at the grove that the grove was experiencing more monarch breeding with larvae and pupae still present on nearby milkweed. In fact there was a monarch in "J" hanging on the side of a milkweed as well as a chrysalis on a table for everyone to see.

The next morning we returned to the grove and watched as the monarchs responding to the increasing winds throughout the morning and afternoon.
We made several trips during the course of the day observing monarch behavior at the Pismo Monarch Butterfly Grove and another site at Oceano Campground where we staying. The winds were blowing from the south and shifting at times to the southwest and southeast, increasing in intensity to 45 to 50 mph. Already by 10 a.m. the monarchs were beginning to concentrate on the north side of the inner tree circle, particularly on the cypress trees.

We found them taking to the air trying to relocate to a more favorable location and a strong gust would toss some into nearby trees or a few even to the ground. Their storm-tossed flight was halted only temporarily as the monarchs were persistent in their determination to find a safe port to weather the storm.

By afternoon many of the monarchs had left the safety of the inner tree circle and moved to the
northern perimeter of the site for a safe haven from the persistently increasing winds from the south. Some moved to the eucalyptus trees across the highway. We watched as the monarchs began to form small clusters on the northern side of the cypress trees in high locations but tucked under the highest branches. But others moved to the lower branches of small oaks and other bushes right above the creek in the grove. Many of the smaller clusters were forming on branches only about eight to ten feet high right over the creek. We knew that the rains would blast in from the north later that evening and were concerned about monarch survival on these lower locations.
 While a safe refuge from the winds, heavy rains could toss them into the creek not too far below. Sustained winds were now at 31 mph with gusts over 50 mph as darkness fell.

Then the rains came. Winds howled as heavy rains from the north blasted the area in darkness. At 11 p.m. an imminent flood siren pealed waking everyone in the campground to be aware of possible rising water. While we were lucky to have a campsite on slightly higher ground, others had standing water of two to four inches deep nearby. Road dips filled with standing water as did low areas nearby.

It was 52 degrees and cloudy at 9 a.m. when we walked out to the nearby monarch site at Oceano campground. Most of the monarchs were tossed to the ground with only about one quarter still clinging to tree branches above.
At first we saw one, then about 20 to 25 monarchs grasping the tops of twigs in the ravine, but as we looked closer, we saw hundreds. Most were closed-winged but then one began to shiver and flew to a nearby tree branch. Despite being storm-tossed to the ground, overall these monarchs looked good - they were survivors. The poison oak in the area made it tricky to observe at times.

By 9:30 a.m. it was partly cloudy and we returned to the Pismo Beach Monarch Grove. Temperature was still at 52 degrees as we arrived. No one was there. Branches and leaves now covered the walkway. The monarch clusters in the tree circle were greatly reduced, although we did find smaller numbers of monarchs lower in the trees. It took a few moments to adjust your eyes to see the monarchs covering the ground.

Their closed wings looked like other dead leaves littering the grounds. A few were covered with mud.
But then, as the temperatures began to slowly warm, orange wings flew open across the area, pulsing rhythmically, as grounded monarchs began to shiver, warming their chilled muscles. One by one, they lifted off to the safety of nearby trees.


But what happened to the monarchs that decided to move to the north side of the cove? We walked towards the bridge and found the creek swollen, brushing the bottom of the bridge. Small streams were spilling over the walkway and we looked for downed branches to access the area where the monarchs moved the day before.
Our feet were soaked from all the moving water, but we finally made our way to where we last saw the monarchs as night fell. The monarchs high in the cypress tree seemed to fare well and any that were storm-tossed fell on higher ground. But the monarchs that were hanging about the now swollen creek were gone.
We found just a few in small clusters about 10 to 12 feet about the ground and one lone monarch clinging to a branch just inches above the rushing water.

We made several trips to both the Oceano and Pismo Beach sites during the day watching the monarchs recover and once again cover the trees with orange wings warming in the rising sun. By nightfall all was well and the monarchs were once again tucked in to their traditional branches in the groves. The storm offered us a unique opportunity to witness the monarch's storm survival strategies.

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