CWF is celebrating International Migratory Bird Day all week long
by Kelly Triece, Private Lands Biologist
Kelly Triece’s blog on the Golden-winged Warbler is the first in a series of five to be posted this week in celebration of International Migratory Bird Day (IMBD). IMBD 2016 is Saturday, May 14. This #birdyear, we are honoring 100 years of the Migratory Bird Treaty. This landmark treat has protected nearly all migratory bird species in the U.S. and Canada for the last century.
Ruth Bennett, studying GWWA in their wintering habitat, with a recently banded Golden-winged Warbler Photo by Mayron Mejia
The Golden-winged Warbler (GWWA), Vermivora chrysoptera, is a Nearctic-Neotropical Migrant songbird that spends half its life in Central or South America and the other half in North America. This small songbird is less than 5 inches long with a slim body and short tail. GWWA are most noted by their yellow-patched wings, yellow cap and black-and-white face.
Right now, GWWAs are migrating to their breeding habitat in North America. They return every spring to the Upper Mid-west and Appalachians, including New Jersey, where they find a mate, breed and rear their young. The breeding range of the Golden-winged Warbler extends along the Appalachians from the northern portion of Georgia in the south to Vermont in the north.
Our latest report from the online observation database, eBird, reported a Golden-winged Warbler sighting in Cameron County, Texas on May 3! They are currently migrating north, and do so mostly at night. GWWA migrate at night to avoid predation from day-time predators such as American crows or Blue jays. The skies are also friendlier at night with less turbulence, allowing the birds to stay the course more readily. In addition, migrating birds need to forage to maintain energy during the long migration and must do so during the day. So flying at night gives the bird’s ample time to chow down! Get ready New Jersey!
Golden-winged Warbler Photo by D. Kenny Golden
In September, after breeding season, Golden-winged Warblers migrate south, mainly through a corridor of states east of the Mississippi River and west of the Appalachians. The winter range for this species is southern Mexico and Central and South America, including Colombia and Venezuela. Migrants are seen most commonly in late April and May, and during September.
Recent studies have shown that Golden-winged Warblers can also migrate in response to storm events (Streby et al. 2015). While GWWAs migrate long distances twice a year to occupy their breeding and wintering habitat, they may also “mini-migrate” to avoid large storm systems. Last year, a study in Tennessee found that Golden-winged Warblers evacuated their breeding territories days before a large storm system. After the system they returned to their breeding grounds and continued to defend their territories and breed. This research is important as it may provide future insight into the energetic demands and fitness consequences of these “mini-migrations.” As climate change continues to increase the frequency and severity of large storms along the east coast the “mini-migrations” may impact the overall fitness of the species as the energetic demands of migrations are great (Streby et al. 2015).
Golden-winged warblers are threatened due to habitat loss in their breeding range and wintering range. Golden-winged warblers require early successional, young forest habitat to nest and raise their young. Young forest habitat, also known as scrub-shrub habitat, is new or regenerating forest that is less than 20 years old. In its breeding range in North America, habitat loss has occurred as forests have matured. In the past 30 years, over 11,000 acres of upland shrub and emergent wetland habitat have been lost to succession in New Jersey. In a naturally occurring system, where fire, wind, flooding and other disturbances are not controlled by humans this age class would be more evenly distributed. In addition, loss of quality stopover and wintering habitat may also be contributing to declines. Golden-winged warblers are a federal species of concern and endangered in the state of New Jersey. Through management and proper forestry techniques, more diversity can be created to balance the age of the forest. This type of forestry management can help protect the Golden-winged warbler in its breeding range.
Kelly Triece is the Private Lands Biologist for Conserve Wildlife Foundation of New Jersey.
Reference: Streby, H. M., Kramer, G. R., Peterson, S. M., Lehman, J. A., Buehler, D. A., & Anderson, D. E. (2015). Tornadic Storm Avoidance Behavior in Breeding Songbirds. Current Biology, 25(1), 98-102. doi:doi:10.1016/j.cub.2014.10.079