Trying to keep track of individual winter hummingbirds!
winter hummingbird Definition: (Noun). Applied loosely and generally to any hummingbird appearing or remaining in Louisiana during the winter; birds are most often detected in gardens managed for hummingbirds. Any western hummingbird 1 species appearing in Louisiana as early as July. Individual Ruby-throated Hummingbirds that are known to have lingered from the fall or appear during the winter.
1 western hummingbird Definition. (Noun). Subset of winter hummingbird species. Includes several species that breed in the Western US or NW Canada and appear in Louisiana during the fall and winter: Black-chinned, Anna’s, Calliope, Broad-tailed, Rufous, and Allen’s, hummingbirds. Also includes southwestern US and Mexican species that show a fall-winter occurrence pattern in Louisiana: Blue-throated, Broad-billed, and Buff-bellied hummingbirds. Species from these areas that have not yet occurred in Louisiana would be also considered a western hummingbird.
Attracting hummingbirds has always been popular, but interest in hosting winter hummingbirds is on the upswing. Many, even casual, hummingbird enthusiasts now realize keeping up feeders will not stop southbound hummingbirds from migrating or lure unsuspecting hummingbirds to their death by keeping them too far north. In fact, feeders probably have the completely opposite effect. They may save birds that have wandered off course or are programmed to winter in the "wrong" place by providing an important or supplementary energy source. This is especially important if a bird's other food resources are temporarily or permanently lost (e.g., loss of flowers and insects during freezing weather). Many southeastern birders (and gardeners) have successfully attracted winter hummingbirds not only by keeping up feeders, but also by providing late fall and winter blooming plants that are used by hummingbirds. Depending on the level of hummer enthusiasm, potted plants can be maintained through the winter, if protected during a freeze. Those furthest south fare the best, plant- and hummingbird-wise, especially those in USDA zones 8B and higher where winter temps are generally less hostile. The majority of late winter hummingbird records from the eastern US are concentrated along southern and especially "coastal" corridors with more moderate winter temperatures.
Trying to keep track of individual winter hummingbirds adds another dimension. With just a handful of qualified, licensed, active hummingbird banders in the entire SE US, only a relatively small percentage of the birds reported are captured and individually “marked.” This is especially true early in the season when many birds tend to feed at flowers, rather than on feeders, and therefore, are more difficult to lure into baited traps. Because hummingbird leg bands are often difficult to see, and nearly impossible to read, most banders will "color-code" captured birds by applying non-toxic paint on the crown feathers. However, many birds avoid capture, and marked birds can remove or alter their color-code by scratching the paint with their feet. The next best way to keep track of individuals is by using a combination of detailed plumage characters. Yes, it really is possible to do this in many cases, but it requires time and patience. This is an excellent exercise in observation and recording detail, and you can really learn more about individual birds and their behavior. Monitoring individual hummingbirds may shed more light on their behavior, resource requirements, and timing of occurrence, movements, and distribution in our area.
Time to review basicsBefore you launch into the identification of individual hummingbirds, it might be a good time to review hummingbird id basics (LOS News Nos. 188 and 189; also available on the LOS website at http://www.losbird.org).
Each bird is unique – or is it?
During last winter's hummingbird season (from late October through March), we hosted approximately 40 birds: 20 Rufous, 9 Black-chinneds, 4 Calliopes, and (a minimum of) 7 Ruby-throateds. We admittedly had a pretty good winter. Seven of these birds remained into early spring beyond the arrival (14 March) of spring Ruby-throateds. One individual was continuously present from late October on. This bird remained through leaf fall, complete loss of flowers following a freeze, inundations of yellow jackets and honeybees, some serious competition with other hummingbirds, and being captured to read its band! The only thing that seemed to remain constant was that the feeders never froze (because they were replaced if necessary before dawn) or went empty! At any one time last season, birds present in our yard ranged from 2 to 8 individuals, most of the time averaging about six birds (scattered over 4 acres).
So, how do we keep track of individuals? First, we record the appearance of unmarked birds (e.g., not banded or painted by banders) when the bird is first observed. We use a template (Fig. 1) that DLD designed for this purpose. We have found that a template makes recording details quick and easy. A full-sized blank template is available at the LOS webpage. We fill in plumage details on the template and the picture is modified through time if we obtain better “looks” or the bird’s appearance changes. There is plenty of room for scribbled notes. If you are potentially dealing with multiple birds, it can get confusing. Try to focus on one bird at a time to recognize as many identifiable features as possible. There are two challenging aspects to this exercise: 1) being able to recognize the same individual (potentially over a long period); and 2) being able to differentiate new individuals.Turnover
Birds may come and go from your yard during the course of the winter season, or perhaps leave altogether. We have closely watched known individual hummingbirds day after day now over several winter seasons. During our first few seasons, none of our winter hummingbirds remained in our yard through the winter moving to other yards in the neighborhood or disappearing altogether (more on that later). From this, we were able to document that winter hummingbirds were capable of leaving a "hummingbird haven".2 The last few seasons, we have begun to successfully host some individual birds through the season, but have noticed that while some birds remain, others still disappear. More recently, we have actually attracted birds from nearby yards that stayed part or the balance of the winter, instead of losing them to those same yards. And, finally, there is the phenomenon of the "weekender." These birds are detected infrequently. They may include "residents" from nearby yards (description discussed with neighbor), birds that may be constantly in our yard, but too difficult to detect on the average workday (when only a short time can be devoted to searching for hummingbirds), or making irregular visits from some other unknown site. This does beg the question: How do you know whether a bird is a "new" bird or one that may already be present or was present earlier? Is there turnover? Although there may be more turnover during the season than we realize, certainly every new observation does not represent a new bird. How many birds should you count as different individuals? A conservative approach is best; sometimes it is just not possible to be sure that you have multiple individuals that are superficially similar. Of course, the probability that you have a new bird diminishes somewhat with increasing rarity of the species.
2 Hummingbird haven
. Definition. (Noun.) Any site of variable size that has been equipped with feeders (or flowers) to attract and feed winter hummingbirds. Behavior shiftsIt has been suggested that a "new" bird can be recognized by behavior different from a bird already present or present earlier. We consider specific behaviors to form a bird's “routine." These include whether a bird is relatively tame versus wary, aggressive or dominant versus passive or submissive, secretive, or conspicuous. It also can include the bird's choice of a specific area in the yard, using specific perches, feeders, or flowers. Most birds do develop some sort of “routine” if they linger for more than a few days. A change of routine might suggest a "new" bird. An interesting observation from our yard is that recognizable individuals can change their routine. A behavior shift alone, then, is not adequate to document the presence of a new bird. Of course, the most dramatic change in routine is that the bird departs! Why a particular bird that seems so “comfortable” in its own spot in a hummingbird haven with ample flowers or feeders, would choose to leave after an extended stay is unclear. Three obvious potential explanations are: 1) the bird left because it was still “in migration;” or, 2) if left because its niche became unsuitable; or 3) it died. It is difficult to know which of the three options best explain the disappearance of any particular bird. Certainly, niche quality is something that could potentially be quantified. A preferred niche may deteriorate rapidly following a severe environmental event, such as sustained freezing temperatures, loss of flowers (after a freeze), or frozen feeders. Last winter, three of our birds disappeared within 3 days following a flower-killing freeze, which also included six nights 32o or below. This season, Accipiter hawks foraging through preferred thickets appear to have a negative effect on the territory holder. Less dramatic environmental events, such as a decline of habitat lushness (as leaves fall through the winter and thickets become more exposed) or too many honeybees on feeders during warm weather may render a niche unsuitable. Some birds change their routine following the trauma of capture and banding. These situations may affect some birds, but certainly not all birds.
Many routine changes do catch your attention. Probably the most obvious, is when a bird moves away from a preferred location. We have observed birds move (after a week or more and without any obvious provocation) from one area of our yard (and preferred feeders or flowers) to a distant area or relocate to a nearby yard in our neighborhood. We have noted that competition with other hummingbirds often results in this sort of movement. Following fights, we have observed a new bird assume the original bird’s favorite haunt and feeders! This is when it can become confusing, especially if the “new” bird is the same species (and age and sex) as the original. This is also where it becomes very interesting. If you are not carefully monitoring your bird’s appearance, you might miss such an "exchange" of birds.
Individual features to note
In the absence of a color-marked banded bird, a bird's overall appearance is the best way to keep track of individual birds. It is important to note that a bird's appearance is not static. Keeping track of the changes is as interesting as keeping track of the individual birds themselves. There is little published data with regard to timing of molt, and birds wintering in our area may not show the same pattern of birds wintering in traditional sites. As discussed to some degree already in our LOS hummingbird articles, there are several variable features that may help identify individual birds. Two birds are rarely identical, so if you record features listed below, you should be able to distinguish individuals in many, if not most cases. Obviously, one should begin by sorting birds by species, age, and sex. If you have multiple birds of the same species, age, and sex, the real fun begins!
GorgetThe exact pattern and location of spots on the gorget is the fastest way to sort out individuals. The pattern usually varies at least somewhat between birds—often it is very dramatic and a particular individual is easy to recognize based on gorget pattern alone. See LOS News 189, Fig. 4 for example of a gorget pattern. When a bird is observed, imagine the gorget in 4 quadrants (see Fig. 1). Record this pattern as soon as possible following the observation. Refine your description as you acquire better looks.
Immature males and adult females of some species (especially Selasphorus) can have a combination of iridescent colored adult-colored feathers and iridescent green discs forming a pattern on the white throat. The adult-colored feathers have a distinct pattern, which is easy to see when the sun reflects off the feathers, but in poor light it may be difficult to distinguish what portion of the gorget is made up of which feather type (green discs or adult-colored feathers). For example, if the sun reflects off the gorget of a Rufous Hummingbird with two separate spots of orange-red surrounded by a patch of green discs, two distinct spots are obvious. But in poor light, the same gorget appears to have only one larger dark blob (example see "Spot II", Fig. 2). A bird’s gorget can appear fairly different based on lighting, so keep this in mind. The gorget pattern can also appear slightly different based on how the bird is holding the throat feathers or the viewing angle.
Depending on the date and the stage of molt, an individual's gorget pattern may look the same for weeks or months or it may be in a constant state of change. A recognizable feature is missing or molting feathers. As a result, the gorget may have black “holes” or stubby white pinfeathers. The appearance of the gorget will change as molt progresses. In late February and March the appearance of the gorget of immature males changes almost on a day to day basis.
Head, back, sides, and underparts
The location, amount and intensity, or absence of rufous or buff on the plumage is helpful to recognize individuals, in addition to helping distinguish between males and females. Also helpful is whether there is excess wear, especially on the underparts. The usually “white” feathers will appear gray if the tips are completely worn off. Birds usually retain a “general” appearance for some time. Most of the conspicuous body molt occurs during the late winter.
Primaries
Next, concentrate on the primary feathers. Primary shape can help distinguish between species, or help determine the individual’s sex. Then look carefully for the presence of primary molt. The stage of molt can further resolve individual identification. You can get a pretty good idea of the stage of primary molt with a decent look through binoculars in good light. New feathers appear black in contrast to brown older feathers (See Fig. 5, LOS News 188). Unlike other birds, primary molt is difficult to spot when the wing is stretched (e.g., while preening), because the replacement of feathers is more gradual and “gaps” are much less apparent. The best way to view primary molt is to see the folded wing when observing the bird from the side. Note: birds observed in full bright sun may appear to lack wing molt (even when present) because the contrast between dark and lighter feathers can be washed out by glare.
Early in the season, primary molt may seem unimportant, because early arrivals usually have all old primaries. As the season progresses, however, it can be a very helpful character. While a "resident" bird may exhibit active primary molt, a "new" bird often shows no molt or is just beginning molt. In general, adults begin primary molt earlier than immatures. What causes initiation of molt is still not clear. Certainly, some birds begin molt once when they arrive at the wintering site. Onset of molt could also be age-dependent so that immature birds hatched relatively early in the breeding season molt sooner than birds from "later" broods. Again, this may be tied to arrival at the "wintering" site. From our observations of our winter birds, the timing of primary molt can differ dramatically between birds of the same "age" class. Primary molt progresses at a uniform rate, but in at least in some cases (personal observations of our known birds) suspends at primary 8-10, at which point the tail is replaced. Primary molt then proceeds to completion when the tail has been replaced. There is little in the literature with regard to actual timing of wing and tail molt in North American hummingbirds. If you are trying to reconcile whether you have one or two birds, wing molt can be important. For example, a bird observed with no wing and a similar-looking bird with 50% completed wing molt just a few days later are almost certainly different birds. Based on our observations, replacement averages about 1 new primary per week.
Don't forget the tail
The appearance of the tail can also be helpful. Males and females often have somewhat different patterns or rectrix shape. Males have two distinct sets of tail feathers, the first (or immature) set is replaced late the first winter by the adult (definitive) set. The absence of feathers due to active molt is easy to spot in the field. For example, the tail of a bird missing its central rectrices (R1s) will look completely white-tipped because the all-dark R1s are not obscuring the white-tipped outer pairs. Some birds also have damaged or aberrant tails, which can messy or asymetrical. Again, an important point is to remember that birds will likely change their appearance through time.
Bands and defects
And, finally, don’t forget to look for a band. Thanks to the efforts of our hummingbird banders, substantial numbers of hummingbirds are being banded each winter. The presence of a band can help you determine continued presence of an individual during the remainder of its stay, and can confirm that the same bird has returned the next fall. Banded birds become especially valuable when additional information is obtained regarding their arrival, movements, molt, and departure dates. Birds are being confirmed moving from one hummingbird haven to another! Bands can be difficult to see. Hummingbirds have really short legs, the bands are tiny, and fluffed feathers or the perch itself usually obscures the legs. Patience is required, but the band will eventually be revealed, especially if the bird can be viewed from the front or side at eye-level with a telescope. A band is also easier to spot when a bird is preening. It may take several "sessions" with an individual bird to be sure whether it is banded or not.. The band may be on the right or left leg, depending on the bander. Some experts even claim to be able to actually read the number on the band through a telescope by "manipulating" a bird to land in just the right orientation on a feeder perch!
If a bird has been recently banded (within days or weeks), it may have a more obvious clue--a painted forehead. If a bird has tried to remove its paint, the crown can take on some unusual shapes from the "Mohawk" to "horns", sometimes the crown feathers are worn to gray nubs or completely worn off. Our banders in the SE use a variety of paint colors and color combinations, so try to get a good look at the pattern of the crown, if you suspect a marked bird. Though painted crowns are an excellent way to recognize an individual bird, these markings only last so long. Most birds work to preen away the paint, rather than tolerating the patch until the next molt. We have had a female Broad-tailed Hummingbird completely clean off the crown paint in a 24 hr. period--and when we saw the bird the following day, we were initially tempted to call it a different bird (but we confirmed the band). Beware, pollen accumulations on the forehead can look like paint.
Another potential means to identify individual birds is by a wound, or bill defect or plumage abnormality. Just as plumage may change over time, so can wounds, which may heal or further deteriorate. Usually plumage defects (such as albinism) and defective bills (e.g., crossed bill) are more static. Many lingering Ruby-throated Hummingbirds, for example, have problems, such as bill injuries or defects. Over the years, two of our yard Calliopes have arrived with wounds.
New birds - examples from our yard
Figure 2 illustrates six of our immature male Rufous Hummingbirds from last season. It demonstrates how we use the template to record information. The first date of observation is noted along with a “name,” which we found is an easy way to remember individuals. Compare the illustrations. Note that “Menace“ and “Not Menace“ are virtually identical except for stage of primary molt, which separate these two individuals. In almost all cases, there is at least one feature that is unique. A bird is therefore considered “new” if it possesses one or more characters that cannot be assigned to another individual. This can get difficult at times, so we err on the conservative side. For example, two “identical” birds would be considered “one bird” if the two birds were not seen at the same time. Just because a bird is observed on one end of our yard going to a feeder, and an "identical" bird is located in a different place a few moments later, does not indicate that there are two birds. We have observed marked individuals move large distances within moments! (Sometimes we think that they follow us to see what we are up to.) It is possible that multiple “identical” individuals can be present, but the only way to be sure is to see multiple birds at the same time. During the fall of 1998, three virtually identical female Calliope Hummingbirds were present in our yard. We were only able to confirm our suspicions when all three birds were observed at the same time (multiple observers help here). Banders have also discovered additional birds at havens, not detected by the homeowner because multiple birds were assumed to be “one.”
Spot newcomers – keep track of regulars
As mentioned earlier, you may first be alerted to the presence of a “new” bird when a resident bird becomes agitated, calls more frequently ("battle cries" of “ekkadah, ekkadah” ring through the yard), or display flights are observed. Although the new intruder turn out to be only an Orange-crowned Warbler or Ruby-crowned Kinglet, it is worth checking out a change in routine. Did you know that a hummingbird can utter the "battle cry" when perched? The battle may not be aerial, just vocal! Another way to potentially spot a newcomer is that these "naïve" birds check out flower-like objects such as bows or flagging.
New birds can arrive (or depart) in “waves.” If one new bird is present, perhaps there are others. It is important to keep day to day track of the presence of “regulars.” Unfortunately, many hummingbirders have only weekends and holidays to spend adequate time studying individuals as the winter days are short. Though more difficult than the day-to-day approach, it can be done with careful observation. It is important to note on which days birds are not seen. We have found that the best way to keep track of our birds is with a calendar. Table 1 is our completed December 2000 spreadsheet. Birds are checked off on days that they are seen. On this calendar, we also keep track of when we are gone, low temperatures or other yard events, such as the death of the flowers. A blank calendar is on the LOS webpage; we used the program Excel to create ours.
If you build it, they will come, and perhaps even stay
Each year we try to “improve” our yard for winter hummingbirds. During the winter of 2000-2001, we had our best year ever and (for us) a virtual parade of Rufous Hummingbirds. We attribute much of our success drawing birds to the yard by our ornaments (many red bows on the perimeter of the yard), which initially attract birds (especially in the colorless flowerless late winter). We have seen a dramatic upswing in the number of individual winter hummingbirds since we adopted the red welcome bows about five years ago. A red-blooming Camellia or a fully laden Burford Holly would certainly have the same effect, but those natural ornaments are lacking in our yard. Little bows of pink flagging appeared to be especially attractive last season to Black-chinned Hummingbirds (though our yard was apparently not “appropriate habitat” to hold any of these birds).
“Keeping” birds is another story, as alluded to above for Black-chinned Hummingbirds. Probably the best way to “hold” winter birds is to mimic their winter habitat. But that’s difficult for a variety of reasons, so we continue to experiment to come up with the next best thing. Seemingly, the two most important necessities are food and cover. Insects are an important food resource, which never seem to be in short supply in south Louisiana. Last season we watched hummingbirds successfully flycatching insects on sunny tree trunks on mornings in the low to mid-20s! The hummingbirds would also probe directly into lichens or bark.
Late fall- and winter-blooming hummingbird plants are important and from our yard perspective, our recommendations would include the following ornamental perennials: Winter Shrimp Plant and various Salvia species (notably: S. mexicana Compton's, S. iodantha Louis Sasso, S. involucrata var. puberula, S. elegans, and S. karwinskii. But those plants are only as good as the winter is mild (we had none of those remaining for hummingbirds last winter after the freeze on Dec. 19). So, feeders have to make up the difference in the absence of flowers. Hummingbirds ignored many of our feeders last winter. Grouping several feeders in a hummingbird’s preferred thicket may or may not help "hold" a bird. In our experience when we have done this, as often as not the bird leaves or relocates elsewhere in the yard, especially just after arrival when the bird is still "scouting" the best niches. It is usually obvious which feeders are preferred and which are not used. But how many feeders? That’s a good question. We continue to experiment in excess, with large numbers of feeders placed for "advertising" visibility earlier in the fall, and then gradually "customized" to individual birds and thickets as the fall and winter progresses.
Our yard’s ability to “hold” birds seems to be correlated more to the amount of under-story and mid-story evergreen shrubbery. Most important appear to be thickets comprised of azaleas, camellias, Russian and Sweet olives, Ligustrum spp., and bamboo, especially those associated with vine tangles, brush piles, or clumps of Rubus spp. The best thickets are adjacent to open air space and sheltered by large Live Oaks. As we improve our evergreen cover (we initially started with a mowed 3-acre lot under predominately deciduous trees), we are able to hold more birds longer through the winter. When we first moved in no birds would winter, then some would linger (departures seemed to coincide with loss of cover), and finally a few birds have stayed with us through the “mild” winters. But many birds still leave. Cover appears to be a key component.
Donna L. Dittmann & Steven W. Cardiff
435 Pecan Drive
St. Gabriel, LA 70776