Biodiversity Corner

Testing the Strength of a Spider Web

Eugenio González, Director-Soltis Center 

Among the bushes of a blue porterweed cluster (Stachytarpheta jamaicensis) in the Soltis Center, a golden silk orb-weaver spider (Nephila clavipes) built a 50+-centimeter diameter spider web. Although it is clear the web was designed for trapping all sort of insects, other visitors of the blue porterweed can also get trapped. That was the case of a violet headed hummingbird (Klais gumeti), which accidentally missed the spider web, getting stuck among the sticky threads. The desperate hummingbird tried to escape by swinging its wings strongly, but the web showed to be stronger. While filming the already exhausted hummingbird, another individual of the same hummingbird species got trapped. Now, there were two individuals trying desperately to escape the web. Although both hummingbirds fiercely tried to break the spider web threads, the spider web showed to be stronger than the joint effort. Finally, we decided to give another life opportunity to the hummingbirds by releasing them from the spider web. Hummingbirds did not know that it could have been their last try, since a single thread of the anchor silk has a tensile strength of 4×109 N/m2, which exceeds that of steel by a factor of eight (ultimate strength of steel 500x106 N/m2). View the short video here.

New record of an unusual mammal: The Bushy tailed Olingo (Bassaricyon gabbii Allen, 1876)

 Francisco Morazán, Soltis Center Research and Academic Programs Assistant 

In July (same date of the observation of the Cope's Brown Treefrog -, by the Soltis Center frog pond, a couple of Bushy tailed Olingos were observed for first time in the canopy of the trees surrounding the frog pond.

In the beginning, we thought they were Kinkajous, which are quite similar to Olingos and had been sighted in this place before; however, after few seconds, we confirmed they were Olingos due their greyish coloration and the faintly banded, not tapered-prehensile tail. Equally, their sounds or calls confirmed we were observing a Bushy tailed Olingo.

The Northern Olingo, as it is also called in the literature, is the largest and most sexually dimorphic olingo species (Helgen et al. 2013). Located in the central portion of Central America, from northern Nicaragua to Costa Rica, and as far south as Western Panama. This species is found from the sea level up to the montane and foothill forests; however, it is most commonly encountered in forests above 1,000 masl and extends, at least as high, as 1,700 m, and probably as high as the upper limit of forest on the highest peaks in Costa Rica (Helgen et al. 2013)

Although not much is known about the Olingo diet, it has been reported feeding on fruit and nectar in trees (Helgen et al. 2013). According to Reid (2009), its diet also includes fruits of Cecropia sp,Quararibea costarricnesis, Inga sp trees. A video recorded in Costa Rica shows this species feeding on fig trees (Ficus spp) and displaying social behavior (González-Maya and Belant 2010). Invertebrates and small vertebrates are probably also taken; as reported by Reid (2009) of a Bushy- tailed Olingo catching and eating a Mexican Deer Mouse (Peromyscus mexicanus).

Although nocturnal, this arboreal Olingo may be seen during the daylight. The Bushy - tailed Olingo is much more active than the Kinkajou and quickly moves away from a spot light, running from branch to branch with great agility. During the day, it dens in tree holes or sleeps on branches. Individuals are usually solitary, but may be seen in pairs or small groups and may feed in the same tree with Kinkajous.

Very little is known of the population size of this species, and its status in the wild is considered of “least concern” by UICN (2017), but it is assumed to be in decline due to loss of forest. Included in CITES Appendix III by Costa Rica.
Gonzalez-Maya, J. and Belant, J. 2010. Range extension and sociality of Bushy-tailed Olingo Bassaricyon gabbii in Costa Rica. Small Carnivore Conservation, Vol. 43: 37–39
Reid, F. 2009. Mammals of Central America and Southeast Mexico. Oxford University Press. Second Edition. 346pp
Bushy tailed Olingo (Bassaricyon gabbii )  The IUCN Red List of Threatened Species 2016: e.T48637946A45196211. Downloaded on 12 September 2017.

Treefrog Ecnomiohyla Miliaria

 New record of the Cope's Brown Treefrog (Ecnomiohyla miliaria Cope 1886) at the Soltis Center for Research and Education.
Francisco Morazán, Soltis Center Research and Academic Programs Assistant

On mid-July 2017, on the trail to the waterfall of the Soltis Center, a juvenile of Cope's Brown Treefrog (Ecnomiohyla miliaria) was found for first time (Figure 1), a very rare frog species in Costa Rica. According to Savage (2002) this canopy treefrog species is rarely seen and collected in Costa Rica.  This species has been reported previously between 600 and 1200 m elevation on both the Caribbean and Pacific highland slopes of western Panama and Costa Rica, and from an unknown locality in Nicaragua and central Colombia (Duellman 1970). This nocturnal treefrog is mostly found in the canopy trees of the primary humid lowland and montane forests.  

Unlike most anurans, the males of this species are larger than females, defending their territory or oroviposition sites, using fiercely their prepollical spines to slash their rivals (Savage 2002). Eggs are deposited in tree holes, which is also where the larvae develop.

Although not much information on this species is available regarding its physiology and ecology, it is believed that the thick, rugose skin and presence of osteoderms may provide some protection against desiccation, perhaps enabling the frogs to live in more arid microhabitats (Duellman 1970). An arboreal lifestyle is indicated by the large discs and dermal fringes, the latter seeming to confer the ability of gliding, although only two observations have provided evidence for this behavior. The arboreal lifestyle and resilience to desiccation has been suggested as evidence for the Fringe-limbed treefrog's home in the forest canopy (Duellman 1970).

According to IUCN 2007 Red List of Threatened Species, Cope's Brown Treefrog is classified as vulnerable, being the major threat the loss of primary forest habitat due to agricultural expansion, logging, and human settlement. There is no information on the population status of this rarely seen, high-canopy species, neither is not enough data available to estimate species abundance.

Figure 1. Juvenile individuals of Cope's Brown Treefrog (Ecnomiohyla miliaria) found at The Soltis Center in 2017.  (Photo F. Morazán).

Duellman, W.E.
(1970). The Hylid Frogs of Middle America. Volume 1. Monograph of the Museum of Natural History, University of Kansas.
Savage, J.M. 2002. The Amphibians and Reptiles of Costa Rica. Chicago: University of Chicago Press.
Ecnomiohyla miliaria. The IUCN Red List of Threatened Species 2010: e.T55561A11319134. Downloaded on 19 July 2017.

The Snowcap Hummingbird (Microchera albocoronata), an emblematic bird species of the Soltis Center’s AviFauna

Most of the vertebrates at the Soltis Center are represented by an exuberant avian diversity with more than 300 species already registered. Among all of those species, standing out by its color, size and rareness, the conspicuous hummingbird species commonly known as the Snowcap (Microchera albocoronata), is a flagship species that represents the Soltis Center fauna.

Being found only from Honduras to western Panama, this is the only species of the genus Microchera in the Trochilidae family. The Snowcap is part of the selected group of over a dozen bird species that have also been reported at the Soltis Center and considered regional endemics due to the narrow natural range of distribution along the Central America region. Additionally to abovementioned attributes, the presence of the Snowcap Hummingbird at the Soltis Center represents an interesting biological fact for the part of the country in which the center is located, since the species is more commonly found at higher elevations.

This species has sexual dimorphism once the individuals reach adulthood, being the males immediately recognizable by the dark blue/purplish overall body color with some bronze tones mostly on upper parts with a striking white cap, while immature males and females look very similar having greenish color on top of their bodies with white color on their breast, which looks duller or grayer in the case of males. This little hummingbird has a body length of approximately 6-8 cm long.


Photo: The extraordinary and rare Snowcap Hummingbird commonly found at the Soltis Center.

Since the beginning of operations of the Soltis Center in 2009, this extraordinary species has been reported year round. However, the second half of the year has typically been the best time to find it locally, having a historic record of sightings during the first week of October 2014, when over a half dozen of individuals were spotted interacting around the purple porterweed plants (Stachytarpheta frantzii) with other hummingbird species such as Rufous-tailed Hummingbird (Amazilia tzacatl), Blue-chested Hummingbird (Amazilia amabilis), Violet-headed Hummingbird (Klais guimeti), Bronze-tailed Plumeleteer (Chalybura urochrysia), Green-thorn Tail (Discosura conversii), Black-crested Coquette (Lophornis helenae) and White-necked Jacobin (Florisuga mellivora), among others.

In order to enhance the role of the Soltis Center as an institution supporting and producing new and relevant scientific information, while preserving the native biodiversity of the Northern part of Costa Rica, the Table below shows the Central American endemic bird species that have been reported at the Soltis Center grounds since 2009.

Table 1. Central American Endemic Bird Species found at the Soltis Center

Family English Common Name Scientific name
Psittacidae Crimson-fronted Parakeet Aratinga finschi
Trochilidae Snowcap Michochera albocoronata
Trochilidae Coppery-headed Emerald Elvira cupreiceps
Trochilidae Purple-throated Mountain gem Lampornis calolaemus
Trogonidae Lattice-tailed Trogon Trogon clathratus
Rhamphastidae Yellow-eared toucanet Selenidera spectabilis *
Picidae Hoffmann’s Woodpecker Melanerpes hoffmannii
Thamnophilidae Streak Crowned Antvireo Dysithamnus striaticeps
Cotingidae Snowy Cotinga Carpodectes nitidus
Cotingidae Three-wattled Bellbird Procnias tricarunculatus
Cotingidae Bare-necked Umbrellabird Cephalopterus glabricollis
Trogloditidae Stripe-breasted Wren Cantorchilus thoracicus
Trogloditidae Black-throated Wren Pheugopedius atrogularis
Turdidae Black-faced Solitaire Myadestes melanops
Thraupidae Blue and gold Tanager Bangsia arcaei
Thraupidae Black and Yellow Tanager Chrysothlypis chrysomelas
Thraupidae White-throated Shrike Tanager Lanio leucothorax
Thraupidae Plain-colored Tanager Tangara inornata *
Emberizidae Sooty-faced Finch Arremon crassirostris *
Cardinalidae Black-thighed Grosbeak Pheucticus tibialis
Fringillidae Tawny-capped Euphonia Euphonia anneae

Species marked with a (*), also reach certain parts of South America, such as Ecuador and Colombia and the northern most location of their records includes Costa Rica.