# Hummingbirds proved more effective pollinators than bees in two Costus species in Costa Rica

- Published: 2026-11-10 22:03 UTC
- Section: Life & Health › Biology & biochemistry
- Tags: hummingbird pollination, bee pollination, Costus kuntzei, Costus wilsonii, pollinator effectiveness, pollen transfer efficiency, reciprocal translocation, elevational gradient, montane cloud forest, New Phytologist
- URL: https://realtech.media/news/rt-89759c733795c34b6d90ed7f_hummingbirds_proved_more/

**Per-visit pollen transfer was higher for hummingbirds than for bees, even though bees visited more often. Bee visitation did not decline with elevation, the authors report.**

![Hummingbirds proved more effective pollinators than bees in two Costus species in Costa Rica](https://realtech.media/media/2026/11/75c661ebd27550df.jpg)
*innovanews.ru*

A team from the University of California, Santa Cruz, with a lead author now at Lund University, tested why tropical flowers shift from bee to hummingbird pollination. The results appear in New Phytologist. The work was done in Costa Rica on two sister species of Costus: C. kuntzei, with ancestral bee pollination, and C. wilsonii, with derived hummingbird pollination [1].

The researchers measured how often pollinators visited flowers and how efficiently each visit transferred pollen, and combined these into an estimate of pollinator effectiveness. They also ran reciprocal translocations of both species along an elevational gradient [1].

## Hypothesis and field design

A longstanding but untested hypothesis holds that reduced bee visitation in tropical montane cloud forests repeatedly drove the evolution of hummingbird pollination. The alternative tested here is that higher pollen transfer efficiency drives adaptation to hummingbirds regardless of bee availability [1].

The translocation sites lay within and outside each species' range and at their elevational boundary. Within their own ranges, the species are specialized on bees or on hummingbirds [1].

## Efficiency versus visit frequency

Pollinator effectiveness was higher for hummingbird-pollinated C. wilsonii because of greater per-visit efficiency. This held even though bee-pollinated C. kuntzei received more visits [1].

In the translocations, C. kuntzei showed uniform bee visitation across habitats. For C. wilsonii, hummingbird visitation increased with elevation [1]. The authors conclude that floral adaptation to hummingbirds is likely driven by higher hummingbird visitation in montane environments combined with greater per-visit efficiency, rather than by declining bee visitation with elevation [1].

Senior author Kathleen Kay said bees were still present and visiting flowers in the cloud forest. She noted that bees comb pollen from their bodies to feed offspring, whereas hummingbirds focus on nectar and carry more pollen between flowers.

Lead author Pedro Juárez described the change in flower form: bee-pollinated flowers often have a broad landing platform, nectar guides and scent, while hummingbird-adapted flowers can be smaller, more tubular and less scented. He added that shifts in pollinators can help create new species, because flowers adapted to different pollinators may become reproductively isolated.

The authors say the results point to looking beyond visit frequency and toward how efficiently pollinators move pollen.

## Sources

1. [New Phytologist](https://doi.org/10.1111/nph.71291)
2. [innovanews.ru](https://innovanews.ru/info/news/zoo/kolibri-okazalis-bolee-effektivnymi-opylitelyami-chem-pchely)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-89759c733795c34b6d90ed7f_hummingbirds_proved_more/