Our Customers: The Hummingbirds at Reserva las Tangaras

Hello again everyone! Katie and Nick here, welcoming you to our third Reserva las Tangaras (RLT) blog post. We hope that you pour a cup of something delicious and enjoy this month’s entry!

Many of you faithful RLT blog readers will know, as managers of the reserve we not only care for the property, engage with locals and tourists who visit us, but we also conduct a variety of long-term avian based research projects. One of the most popular of these research projects is a daily hummingbird survey. A photo of a female White-whiskered Hermit (Phaethornis hispidus) visiting one of the RLT feeders is below.

Every day since January 2014 (that’s over 7 years of data at this point!), the managers of RLT have conducted a one-hour long survey of the hummingbirds who visit our feeders. There must be three feeders out during the survey and each feeder must be filled with the exact same sugar solution of 1 part sugar to 4 parts water. If you think this seems silly, that hummingbirds will drink sugar water no matter the solution…tell that to Alaine Camfield, in his 2003 paper “Quality of Food Source Affects Female Visitation and Display Rates of Male Broad-tailed Hummingbirds”. This paper is available in the below references if you are interested, but evidently the 25% sugar solution MATTERS to the hummingbirds. So anyway, data collected includes hummingbird species, number of individuals, the number of individuals of each gender within sexually dimorphic (meaning, species where the male and female can be identified based upon their plumage, size, or other outward characteristics) species, and anything else that may be of note. Other observations that may be noteworthy include behaviors observed (ex. mating, aggression between birds, preening, etc.), if a bird has an identification band on its leg (as seen in the photo below of a female, Green-crowned Brilliant), or if a bird has a key identifying characteristic (ex. Missing a leg, broken wing, abnormal growth, etc.). As you can imagine, this has produced quite the dataset over the years with a plethora of information.

But, we keep asking ourselves the same question day after day…why? Why are we doing this survey? What is the point? What is the collection of this data telling us? Why is it important that we do this? We’ve been here for three months collecting this data Every. Single. Day. And for what purpose? So, we did a little research and decided to look into it a bit further…

Firstly, why are we doing this survey? What is the point?

Well, at its most basic level. We are conducting these daily surveys to obtain a population estimate of the hummingbirds which visit feeders in this area. By noting all the various species, counting the number of individuals, and monitoring banded individuals; we are collecting information on the general hummingbird population local to this area (a neo-tropical, montane cloud-forest with a study area at an altitude of 1350m in secondary forest, boarding riparian and primary forest) during all times of day across the wet and dry seasons (there are technically only two seasons here, not four as in temperate environments). Also, as we are a nature reserve since 2005, our study can be replicated in an unprotected area for better comparison as to the importance of nature preservation and its positive effects on the overall health of the ecosystem, but specifically on hummingbirds. This means that due to observed trends over time, we have a fact-based estimate of what species we will see in this environment during any time of year. This can be important information for presentation to government or political officials in the argument against deforestation, planned destruction of natural habitat, or the excessive growth of “eco-tourism” operations near or in protected areas. For example, don’t clear that 2 hectares of primary forest to build an “eco-lodge” because there is a high local population of the rare, Purple-bibbed Whitetip (Urosticte ruficrissa), which thrives in montane forest undergrowth and may be lost if its habitat is destroyed. Do we have proof of how exactly this habitat loss affects hummingbirds? You bet we do! Check out Hadley et al. 2018 (full citation available below in references) for “Forest fragmentation and loss reduce richness, availability, and specialization in tropical hummingbird communities”. Below is a photo of the Purple-bibbed Whitetip male, as they happen to be one of the more prevalent species to visit our feeders, despite their rare status in Ecuador and globally. They could be one of the more vulnerable species to anthropogenic impacts such as deforestation and habitat loss.

Secondly, what is this data telling us?

Well, when we sit down and truly look at the data…it can tell us a lot! One thing we have learned according to observations over the last 7 years is that we see a lot of mating behavior between February – May, resulting in lots of juvenile or sub-adult hummingbirds being seen at the feeders in July – October. Mating behavior can be described as active male on male aggression, interspecies aggression, or mating attempts made at the feeder (female sitting on feeder and male approaching from behind), or actual copulations seen (rare!). Juvenile or sub-adult hummingbirds are identified due to their plumage, which may still contain all or most of their post-hatching down feathers. They can also be identified due to their overall body size, bill length, tail length, or wing development.

One interesting study published in a 2018 edition of Plos ONE, highlighted the use of Radio Frequency Identification (RFID) technology to characterize hummingbird visitations at feeders to help elucidate behaviors, clarify population dynamics, and define community structure. Essentially, asking very similar questions related to hummingbird species richness and behavior to our own here at RLT, but in an urban setting…pretty much the opposite of our own. Read more on this in the open journal article Bandivadekar et al. 2018.

Another lesson which is easy to learn, is how the overall populations of each species seem to be fairing over time. For example, according to the data over the past 7 years a few species have consistently had the largest number of individuals coming to the feeders, 1) the Green-crowned Woodnymph (Thalurania colombica), followed by 2) the Andean Emerald (Amazilia franciae), and the 3) White-necked Jacobin (Florisuga ellivora); so, we can assume that those species have a healthy local population. Some species have shown extreme variability in their numbers coming to the feeder, sometimes having very high numbers (healthy local population) and sometimes having very low numbers (unhealthy local population), such as: the Fawn-breasted Brilliant (Heliodoxa rubinoides), the White-tailed Hillstar (Urochroa bougueri), the Brown Violetear (Colibri delphinae), and the Brown Inca (Coeligena wilsoni). These are species that scientists could ask several questions over. Why are they rare during some months and abundant during others? Why during some survey days are they present in high numbers, but on other survey days they are not observed at all? What environmental factors are changing their population density at the feeders? Is it an anthropogenic (human-induced) factor changing their population density at the feeders? Then there are those rare beauties, which are always a rare sight no matter the time of day or the season, such as: the Green-fronted Lancebill (Doryfera ludovicae), the Purple-crowned Fairy (Heliothryx barroti), and the Little Woodstar (Chaetocercus bombus). Does this mean that their populations are locally unhealthy? Or are they perhaps a rare or vulnerable species nationwide or even globally? One scientifically acceptable method that RLT uses in answering some of the above questions regarding hummingbird population health, is that of banding and recording recaptured individuals. By hall-trapping (a method of low-stress, hummingbird capture) birds and collecting basic data on them (weight, age, plumage, brood-patch presence, or absence, etc.), then fitting them with a small identification leg band, we can then continue data collection on that individual over time through recapture and data collection techniques. We can learn how long the individual bird lives, if and when they reach sexual maturity, during which season they develop the most fatty tissue, if they are migratory or year-round settlers, if they produce young, etc. Only results from a long-term data set with recapture capability can teach us these lessons. Studies with results like this can be seen across a variety of hummingbird species, one such example being in Calder et al. 1983 highlighting the Broad-tailed Hummingbird (a U.S.A based species) listed below in the references. You can also read a bit more about this in RLT’s Field Reports from the last 5 years of Bird Banding Expeditions organized by Life Net Nature (LNN): https://lifenetnature.org/

Thirdly, why is it important that we do this? Why does it matter if we do or do not conduct these daily surveys?

Well, it matters for several reasons. One being that a healthy population of hummingbirds in this area determines a healthy density of native and endemic flora. We all know that bees are important pollinators, but did you know that hummingbirds are as well? They are proven to be a key vector in direct pollen transfer, with native and endemic hummingbirds preferring (thanks to evolution!) native and endemic species of plants. The more we know and understand our key hummingbird characters, the more likely we are to know and understand the important flora of this area as well. This is something that may seem fairly obvious, but most of us grow up learning about the bees…not necessarily the birds. If this interests you (as it did me), check out these open and free journal articles on the subject, all referenced below: Feinsinger et al. 1986, Jimenez et al. 2012, and Ornelas et al. 2004.

Another important reason for conducting these surveys, is that there is still SO much we still do not know about some of these species from a basic life ecology level. In a paper from Rodriques et al. 2013, they publish the demographic parameters of a previously undescribed hummingbird species in southeastern Brazil. Simply by observing the same species monthly for 2 years, scientists were able to collect and publish data regarding this hummingbird’s population dynamics, survival rates, sex ratios, mating displays, migratory patterns, and recommended conservation efforts. Here at RLT, with managers onsite 365 days per year, a focused study on each individual species could give us an accurate depiction of each species ecology, also known as a biographical sketch. For example, below is a photo of one of RLT’s most historically common hummingbirds, the Andean Emerald (Amazilia franciae). Managers have been recording high numbers of individuals from this species at our feeders since their inception in 2014, that means we have over 7 years of population data, behavior assessments, site fidelity, and banding data (which is technically in a separate database, but we have it and could supplement our surveys with it!). We have ALL of this knowledge at our fingertips, however there are NO publications (that I could find anyway) which draw out a biographical sketch of this species. What if this is a keystone species of hummingbirds in the neotropical region? We should have its ecology listed out and available for conservationists to use if need be in the protection of environmentally sensitive areas. There are some excellent opportunities here for students looking into higher education, just saying 😉

Well, I hope we didn’t bore you with TOO much science talk during this blog…but that you did come away with some new information regarding our “customers”. Also, just for your information the reason we call the hummingbirds at the feeders “customers” is because tourism in Ecuador is still relatively low, so we are only being visited by the occasional hiker…however, we KNOW that we can depend on these hummingbirds showing up Every. Single. Day. within seconds of our appearing outside with the feeders, hence they are our biggest customers, at the moment.

If you want to come visit us at Reserva las Tangaras and learn more about our “customers” or assist with one of our daily hummingbird surveys, call or WhatsApp us to schedule your visit: +593 96-982-4972 or +593 99-058-7084

We hope that you enjoyed this blog post and that we see you at RLT soon!

Best, Katie & Nick

Bandivadekar, R.R., Pandit, P.S., Sollmann, R., Thomas, M. J., Logan, S. M., Brown, J. C., et al. (2018) Use of RFID technology to characterize feeder visitations and contact network of hummingbirds in urban habitats. PLoS ONE, 13(12): e0208057. www.doi.org/10.1371/journal.pone.0208057[c1] 

Calder, W. A. III, Waser, N. M., Hiebert, S. M., Inouye, D. W., and Miller, S. (1983) Site-Fidelity, Longevity, and Population Dynamics of Broad-Tailed Hummingbirds: A Ten Year Study. Oecologia[c2] , 56 (2/3): 359-364. www.jstor.org/stable/4216906[c3] 

Camfield, A. F. (2003) Quality of Food Source Affects Female Visitation and Display Rates of Male Broad-Tailed Hummingbirds. The Condor[c4] , 105(3): 603-606. https://www.jstor.org/stable/1370686[c5] 

Feinsinger, P., Murray, G. K., Kinsman, S., and Busby, W. H. (1986) Floral Neighborhood and Pollination Success in Four Hummingbird-pollinated Cloud Forest Plant Species. Ecology, 67(2): 449-464

Hadley, A. S., Frey, S., Robinson, D. W., and Betts, M. G. (2018) Forest fragmentation and loss reduce richness, availability, and specialization in tropical hummingbird communities. Biotropica 50(1): 74-83 www.doi.org/10.1111/btp.12487[c6] 

Jimenez, L., Negrete-Yankelevich, S., and Maćıas-Ordónez, R. (2012) Spatial association between floral resources and hummingbird activity in a Mexican tropical montane cloud forest. Journal of Tropical Ecology (2012) 28: 497-506. www.doi.org/10.1017/S0266467412000508[c7] 

Ornelas, F. J., Jiménez, L., González, C., and Hernández, A. (2004) Reproductive ecology of Distylous palicourea padifolia (rubiaceae) in a Tropical Montane Cloud Forest: Hummingbirds’ Effectiveness as Pollen Vectors. American Journal of Botany 91(7): 1052–1060.

Rodrigues, L., Ibanez Martins, F., and Rodrigues, M. (2013) Survival of a mountaintop hummingbird, the Hyacinth Visorbearer (Augastes scutatus), in southeastern Brazil. Ornithologica[c8] , 48 (2)

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