Authored by John A. Gerwin
As I write this, in late February, there are many trees in flower, along with the usual spate of Daffodils and a few other early herb arrivals. Speaking of early, I watched a pair of Carolina wrens gathering large clumps of moss, and begin constructing a nest in a shrub in the backyard, on February 21. It seemed amazingly early. Soon, we will be seeing additional “early birds”.
Normally, we expect to see the first returning Purple Martins to Wake County in early March. That said, our colleague Courtney Rousseau recently reported one from Holly Springs, on February 24. Things are happening earlier and earlier. Considering history, we expect to get a few reports of Ruby-throated hummingbirds in North Carolina in late March. However, most of us in Wake County are accustomed to seeing our first of the year hummers in the first two weeks of April. You can follow along at this website: https://maps.journeynorth.org/map/?map=hummingbird-ruby-throated-first&year=2024
In most migratory bird species, males move through or arrive to a territory prior to the females. This makes sense in that males are racing to get back, get a prime piece of habitat, and establish a territory. Ruby-throats are similar in this regard.
In order to return to its breeding area, a given hummingbird will once again fatten up, the way it did when it was getting ready to head south. An individual that is not in migratory status or condition will weigh 3-4 grams. By the time it is ready to migrate it may weigh 6g. Note that in some cases, the bird has doubled its weight!
So, for most Ruby-throats, March is a month of gluttony as it were – they are still on the non-breeding grounds in a Mexican or a Central American locality. Many are also completing the body molt. Studies show that the head and throat (gorget) feathers will finish growing in by around mid-March.
Indeed, when you see your first males, try to assess the lower edge of the red gorget. A bird hatched in the previous year will often show a somewhat jagged edge whereas the older birds (greater than 1 year old) exhibit a more concise, straight-edge. It’s now always easy to tell with binoculars, but it can be with a digital photograph. That red gorget by the way will look black at certain angles and the way the light is hitting – but the edges are still edges.
Note that across the species broad range, we see quite a bit of variation from year to year in terms of “first seen” dates, and numbers visiting feeders. This is how nature is – there are various factors that affect the timing of movements of birds, and their subsequent distribution. And we don’t understand all of these factors.
As we are seeing more and more, plants are springing forth sooner in the season. Some birds are beginning to nest earlier than ever before. One way we discern these patterns is through the contributions of many amateur naturalists. So if you are so inclined, be sure to post your observations to your favorite website – which may be eBird, or Journey North, or iNaturalist. Here’s the map from 2023 for Ruby-throat observations submitted to Journey North. You can use the slider to see how things look by the week.
And now that you know some hummers may show up as early as late March, you can plan to have your hummingbird feeders ready to go. In the early spring, I prefer to start out with very small quantities of my homemade nectar. I know that visits to my feeders, in early April, we will few and far between. If I put out a feeder full of nectar, it usually gets moldy long before it is consumed. So I wait and see how many hummers seem to be around before I put out a larger quantity.
And remember – these little tykes consume many small arthropods. Indeed these make up about 50% of their diet.
Attached are some pictures to get your ready. I realize this only makes the month of March feel that much longer….. but this year we have Easter Weekend to help with the waiting….. maybe your Good Friday will be super good when you spot your first Ruby-throated Hummingbird of 2024.
All photos by Bob Oberfelder
#1: Here is a “classic” view with full light hitting the gorget of a male Ruby-throat.
#2: This male might be a younger male – the edge of the gorget is slightly jagged. Note the darker area of the throat due to the angle of light, which in this case is not refracting to allow the red wavelengths.
#3: The color on the gorget of this individual appears a bit duller. The color is derived from the interaction of light waves and the feather structures and the way they overlap. Small changes in the structures (wear) or overlapping (puffed up or not) can yield slightly different hues to the red.
#4: A classic “I think I have discovered a new species of hummingbird!”. I have received many such emails and phone calls. Many folks do not realize that the gorget color is the result of structural features of the throat feathers, and not pigments. If the light does not hit and/or refract back in a Goldilocks manner (“just right”), the color appears dark, or black, as in this individual.
Author: John A. Gerwin
February is a chilly, darker month. In the Piedmont of North Carolina, we experience some of the coldest nights, and least amount of daylight. The Ruby-throat is a Neotropical migrant, similar to the warblers, vireos, thrushes, tanagers and more that breed in NC. Most of “our” hummingbirds departed months ago. In NC, some leave as early as late July, others follow as summer turns to fall, and most are gone by late October. They make their way to Mexico or countries in Central America.
Most Ruby-throats migrate south. However, not all of them do. For years, folks have reported wintering hummers in NC. And for some of those years, Susan Campbell and colleagues have caught, measured, photographed, tagged, and released many. They have found a mix of species, but many were Ruby-throats. We do not know why this happens (but we have some opinions all the same. We’ll see if we can get Susan to chime in one month).
During the winter months in Mexico/Central America, a Ruby-throat will be in places with a handful of other species. Keepers of bird lists currently list 340+ species of hummingbirds – all in the western hemisphere. “Neotropics” means New World Tropics. I’ve seen a few Ruby-throats on the west side of Nicaragua for example. Where the Ruby-throat can be found in Nicaragua, one might also find two dozen other species of hummingbirds. I have included pictures of a few of these other species.
In the non-breeding season, the Ruby-throat prefers habitat in areas that are drier overall, and often a bit scrubby (forest openings with second growth, forest edges, and some agricultural settings; among others). They will nectar at flowers we might grow in our gardens – various Salvia species for example. They continue to feed on minute arthropods for protein, and have an inordinate fondness for small spiders.
We know that hummingbirds exhibit some extreme life history behaviors and physiological adaptations. One of these concerns the molt cycle and there are aspects of the molt cycle we do not yet fully understand. Hummingbirds, as a group, rely on flight for feeding. Due to their small size, they are subject to extreme “stress” in order to maintain their high body temperature and functions. All to say, they do not molt quite like other birds. I can’t get into all the details here but will note that adults undergo a complete molt (body and flight feathers) after the breeding season. What’s really curious is that recent research has shown that some individuals undergo a molt in summer and apparently another during the winter.
In songbirds the post-breeding season molt can be completed in 6-8 weeks. In Ruby-throats, it is reported to be slower and much more protracted, when compared to the migrant warbler or thrush.. An interesting aside: in 1936 a researcher counted the number of body feathers on some Ruby-throats; he came up with 940.
At the species level then (Ruby-throat), the molt cycle runs from late summer to mid-winter. Individuals will do things differently, and as mentioned some may begin to molt body feathers in late July. These Ruby-throats then migrate while they are molting (or, if you prefer, molt while they are migrating). The question is, when does that July-molting bird complete the molt? No one knows for sure. One researcher did a fairly thorough study of the molt of Ruby-throats, assessing individuals in Mexico and Central America. His data showed that many Ruby-throats began a molt of the flight (wing/tail) feathers in November and completed it by the end of February. Many (most?) individual Ruby-throats complete the body molt in March, when the males’ new gorget feathers grow in. Still, other aspects of the molt remain unknown. To understand precisely which birds are molting what/when/where, we will need a lot of marked birds that can be followed, month to month.
In February, Ruby-throats are sharing time/space with a large variety of tropical hummingbird species. In addition, they are preparing for the northward migration and some will indeed begin to migrate north during February. Many aspects of their migration also remain unknown – but we do know that some will arrive in the southern U.S. by early March.
Here we provide a link to Cornell’s eBird website for the non-breeding range of the Ruby-throated Hummingbird. This is a page where the user can zoom in and do other ‘animations’ (note also options on the right-hand side).
Finally, I have included photos a few species of tropical hummingbirds in Nicaragua, which ranges overlap that of a given non-breeding Ruby-throated Hummingbird.