Eliminate deer from area will decrese Garlic Mustard growth

In ecosystems worldwide, the presence of overabundant ungulates (e.g. deer, cows) and the invasion of exotic plants are disrupting native communities. A recent hypothesis causally links these problems implicating overabundant ungulates in enhancing invaders’ demographic success. We tested this hypothesis in a forest where white-tailed deer are over-abundant and garlic mustard is aggressively invading. Using long-term, replicated deer exclusion/deer access plot pairs, we quantified population density, growth, and decline of this invader and native plants. We conclusively demonstrate that deer are required for garlic mustard success; its local extinction is projected where deer are absent. Our findings provide the first definitive support connecting overabundant ungulates to enhanced invader success, with broad implications for bio-diversity and ecosystem function.

Birding in Cabo San Lucas, Mexico

          In early February Susan and I flew down to the southern-most tip of Baha, Mexico to the Pueblo Bonita Resort at Sunset Beach in Cabo San Lucas.  The resort was built on the side of a mountain overlooking the Pacific Ocean.  We had beach access but the ocean on the Pacific coast was too rough and dangerous for swimming.  The views were beautiful however, and whales were abundant right off shore.  Both humpback and gray whales spent the winter months calving in the nearby Sea of Cortez and then nursed  and fed along the Pacific Ocean.  We could watch the whales spouting right from our patio and we learned that whenever we spotted a group of boats gathering off shore there were usually whales in their midst.       

                                                                 

          When we first arrived at our room and checked out our patio there was a kestrel sitting on a nearby Saguaro cactus.  Over the week we discovered this was his home turf and on several occasions he chased off a local red-tailed hawk and two common ravens whenever they ventured into his space.  Hooded and Scott’s orioles, lark sparrows, cactus wrens, house finches and house sparrows were regular visitors to the patio and surrounding hillside.

Susan would feed a pair of Scott’s orioles bread crumbs daily but they were hard to photograph as they would remain in the scrubs and only emerge briefly to grab a crumb and then retreat.                                                                                      

          The first morning I took a walk around the compound and observed a large flycatcher sitting on top of a light pole. It took off immediately when a mockingbird landed below it. Fortunately the bird reappeared over the course of the week and I confirmed that it was a Cassin’s kingbird.   

That same morning I found an Ash-throated Flycatcher, a ladder-backed woodpecker and a peculiar thrasher with large dark spots( similar to a wood thrush)on its chest and abdomen.   My “Sibley’s guide to Western Birds” which included the Baha peninsula failed to include this thrasher. There was a pair of them and they repeatedly showed themselves.  Fortunately on my second day a fellow birder stopped to chat.  It turned out he was visiting from Toronto and had gone out on several local birding tours. He told me they were gray thrashers and were found only in the Cabo San Lucas region of Mexico.  I met up with him the next morning and we walked over to the Pueblo Bonita Pacifica resort which was part of our complex but about a mile away. 
 

Endemnic to Baja California - Gray Thrasher

We were searching for a Berylline hummingbird which had been reported in the area but no luck.  Costa’s hummingbirds were plentiful however, as were verdins, orange-crowned and yellow-rumped warblers, gila and gilded woodpeckers.  

          I returned to this neighboring resort with Susan the next day and added blue grosbeaks, white-crowned sparrows, white-winged doves, violet-green swallows, blue-gray gnatcatchers, common ground doves, green-tailed towhees and Western scrub jays. 

          We walked the beach on numerous occasions enjoying the Western and ring-billed gulls, brown pelicans and Brandt’s cormorants that huddled around a single cluster of rocks off the beach.  A shuttle bus provided by the resort would take us to downtown Cabo to visit Pueblo Bonita’s 2 sister resorts.   

Susan's Replacement Husband

         We checked them out but decided we preferred our home resort to the older and noisier downtown area. We did spend time walking along the docks with its many beautiful boats and colorful residents and on one occasion we took a whale watching cruise from the down town port. On exiting the harbor we checked out a local beach and rock formation which was home to some sea lions.  Before we could actually see the sea lions we caught their scent.   The scenery and animals were beautiful but breathtaking in more ways than one. 

          As we got into the deeper waters we followed several small pods of whales including a mother and calf swimming side by side.  After a half hour lull without any activity, our pilot suddenly gunned the engine and took off for the deeper water.  He offered no explanation(at least not in English) and we wondered if he were giving us a thrill ride to make up for the lack of whales.  As it turned out he was in radio communication with the other tour boats who had found a pod of 8 very cooperative adult humpbacks.  We rode alongside the 40 ton mammals for about 15 minutes before they finally disappeared. Our time was up and the driver give us another high speed ride back to the docks.  After disembarking we passed a very elderly Mexican gentleman, cane in hand walking slowly along the dock.  With his weathered looks, loose-fitting white shirt and pants and worn out sandals he looked to be the model for Hemingway’s “Old Man and the Sea”. Several days later back at our hotel we  talked to some tourists who had just returned from a fishing trip. They were very loud and animated in discussing their day’s activities and the excitement centered on our very own “Old Man”  It turns out he was a well known local who frequented the docks and returning fisherman would often offer him a part of their catch.   On this day these folks gave him one of their fish.  Standing beside the water while holding it up to admire and express his appreciation a sea lion jumped out of the water knocking the old man down and stealing the fish.  In spite of his fragile appearance he survived the amphibious assault.  The shocked and amazed tourists(after helping him up and discovering nothing was broken) gave him another fish and that was that.

          On our last day I took a brief walk around the complex and ran into many of the same birds including what I believed to be the gray thrasher. It was deep in some leafless shrub and the lighting was poor. I took some pictures anyway. On returning home and reviewing the pictures I discovered this last thrasher to be a sage thrasher and not the gray. In addition to this pleasant surprise I was treated to two caracaras atop some cacti on the trip from the resort to the airport.  All in all a great end to a wonderful week.

Gary's favorite seafood - Puffer Fish