Birds and Cyclones

Birds and Cyclones

Tropical Storm Isaias on August 3rd, 2020. Source: NOAA 

Tropical Cyclones or in our region Hurricanes are complex weather systems that often bring strong winds, flooding rains, and storm surges to coastal areas. The coastal regions of the Carolinas experiences tropical systems from midsummer to mid-autumn with peak months being August through early October. Wilmington has had its share of cyclones with Hurricanes Hazel (1954), Donna (1960), Fran (1996), Floyd (1999), Matthew (2016), and Florence (2018) bringing major impacts to our area. These storms often come with destruction, loss of life, as well as extensive disruption to natural ecosystems already stressed by human activities. However, like all forces of nature, tropical cyclones are a part of natural processes and may provide beneficial rainfall, wash out stagnate areas, and reshape our coastline. Regardless of their benefits, tropical systems are just as dangerous to birds and wildlife as they are to us. A major storm can permanently reshape ecosystems, and could lead to extinctions in places where rare or endangered animals or plants are confined to a small area such as an Island. Birds are highly mobile and many of our species can survive violent storms or move out of the way in time. 

Birds and Hurricanes

Parula (left) and Redstart (top right) in hedge, 1 month after Hurricane Florence 

Like us, birds are vulnerable to the effects of severe weather, and a large-scale event can cause widespread destruction across a large area. As stated above, birds have the benefit of flight and many of our species can fly inland or to sheltered areas. Additionally, hurricanes generally peak in the late summer or early autumn when nearly all nesting activity is finished and birds are in migration. However in exceptional cases where storms occur in May, June or July, the impacts to nesting cycles can be significant, especially for coastal species. Birds are capable of sensing changes in weather or air pressure follow their instincts to get to cover or relocate. Some birds that end up being caught in cyclones may be carried hundreds of miles out of their normal range. In most situations, birds will emerge from storms largely unharmed, although even weak cyclones (like tropical storms) can significantly alter habitats. This is both beneficial and harmful. In the short term, flooding, loss of trees and saltwater intrusion will reduce suitable habitat, wipe out food sources, and kill many animals. As time goes on, ecosystems will recover or transition into new habitats, providing places for other species to population, or by thinning overforested areas to allow for local diversity. In populated areas, storms can potentially destroy fragment ecosystems or generate hazardous waste and pollution from destroyed buildings, overflowing sewer mains, and debris. Rebuilding, recovery, and oftentimes individual actions to minimize risk to life or property can further stress urban ecosystems as trees and wooded areas are cut back to protect homes, or power lines. In the end, natural will always adapt to changes and birds are often the first creatures to return to storm-devastated areas. 

Bird Notes 

• Coastal birds such as terns, skimmers, pelicans, waterfowl, and shorebirds often fly to inland areas to seek protection. In Hurricane Florence, Black Skimmers and other seabirds were found near fields or retention ponds in Wilmington 

• Many songbirds and landbirds seek shelter in undergrowth, trees, or wooded areas and will often remain safe even if trees fall 

• A significant number of birds end up caught in the storm and may be carried long distances. Everything from songbirds to albatrosses may be stuck in the eye of powerful cyclones, resulting in them being found way out of range 

• I found bird tables and feeders to be particularly busy after storms as insects, natural seeds or fruits, and other food sources are reduced. Hurricane Florence stripped leaves and branches from trees, resulting in birds finding alternate sources of food 

• Most nesting species are finished by August although rare early season storms can affect shore nesting birds. 

Impacts 

Flooded woodland trail in NHC after Hurricane Florence 

'

Tropical cyclones can cause significant changes to regional ecosystems across a large area. In most cases, forests, marshes, and shorelines will withstand storms and recover within a season or two. However, violent storms can wipe out entire swaths of forests, eliminate shorelines or barrier islands, and in the case of threatened island ecosystems, cause total destruction. Hurricane Florence in September 2018 was Wilmington's most devastating storm in recent history and caused the destruction of property, infrastructure, and even isolated the city for several days. In addition to human impacts, the cyclone uprooted, or snapped thousands of trees, cleared coastal and interior forests, and brought saltwater up the Cape Fear River. Nearly two years later, many natural have recovered although the loss of canopy has created different ecosystems.

There are many benefits of widespread weather events. One example of this is the felling of hardwood trees, pines, and willows at Greenfield Lake. Tree losses created new meadows and sawgrass/cattail marshes that allowed Red Winged Blackbirds, Common Yellowthroats, and Indigo Buntings to populate many areas of the park. Snapped or dead trees that were not removed by the city gave Pileated, Red Bellied, and Downy Woodpeckers new places to make cavities and expanded Red Headed Woodpecker habitats.  In other areas, regenerating woodlands and meadows are important for declining species such as Northern Bobwhite, Eastern Towhees, Field Sparrows, and Meadowlarks which need open or brushy habitat to breed. In cases of violent hurricanes that destroy most of the trees in an area, the impacts to forest birds can be extensive and long lasting. Hurricane Hugo destroyed many old growth trees near Charleston SC which will take hundreds of years to recover. Hurricane Dorian in 2019 wiped out most of the Bahaman Pinelands and could result in the extinction of several species including the Bahama Nuthatch. 

On the coast, hurricanes can create new inlets, spits, and islands for shorebirds and seabirds. This may have contributed to increased beach area for Least and Common Terns on Wrightsville Beach in 2019. Storms also erase coastal islands and will destroy any active bird or turtle nests on the beach or nearby grasslands. 

Storms of any magnitude will disrupt migration patterns and it is not uncommon for southbound songbirds or seabirds to be pushed northward by storms. Many birds will perish in storms although the losses are not usually significant enough to affect established most bird species. More significantly, passing cyclones will bring many unusual species to areas. Birds from as far as the Caribbean may end up in North Carolina after storms. In the days or weeks following a storm, keep an eye out for unusual songbirds, seabirds, or waterbirds. Less commonly, tropical cyclones may relocate bird populations northward resulting in expansion in range or newly introduced species. 

Recovery and Conservation 

Coastal Restoration project at Brunswick Town, UNCW field trip Nov 2019

It often takes two to five years for the full impact of any major weather event or a change in climate to be fully realized. For example, a dry summer  or cold winter may not impact this year's acorn or insect populations but may result in a food crash 2-3 years later. More research is needed to determine the overall impact that cyclones have on birds in our area and  across the world. Radar tracking programs, citizen science (like birding groups or eBird data), ecological surveys, and climate research are all important tools that can determine the impacts on birds and other wildlife. The data from research will help help to restore hurricane affected habitats, expand breeding populations of rare or endangered species, as well as find new ways to protect both human interests and the environment as a whole.