Review Papers Claim by Claim

• Macaulay Library search: N = 3,360 photos; iNaturalist: N = 511 photos; three confirmed nectar‑robbing events found Paper dataset and events
• Plant species: Brugmansia sanguinea (mean corolla length = 172.6 mm) — flowers long, historically pollinated by E. ensifera Brugmansia trait and pollination
• Geography & elevation: Napo Province, Ecuador; elevations 3,200–3,350 m a.s.l. (three events) Location and elevation

What the evidence supports

• The photos show E. ensifera feeding via holes in B. sanguinea corollas; two of three events were verified by photographers as secondary robbing through holes made by Diglossa humeralis Confirmation of secondary robbing
• Rarity: within the searched photographic sample the behaviour was extremely uncommon (3/3,871 reviewed records) — consistent with authors' claim that robbing is rare for this species Rarity statement

Limitations, biases, and blindspots

1. Small sample & opportunistic sampling: n = 3 events from photographic archives searched opportunistically; this cannot estimate true frequency, nor temporal or spatial variation Small sample and opportunistic data
2. Detection and reporting bias: photos reflect where people photograph (accessible sites, vocal species, birding hotspots) and may under‑represent other areas or times; absence of robbing in databases is not proof of absence Observer/reporting bias
3. No behavioral quantification or experimental tests: there are no measurements of nectar extraction efficiency, time budgets, or predation risk under robbed vs. legitimate feeding; the proposed anti‑predation function is speculative (admitted by authors) No predation/efficiency data
4. Taxonomic/geographic narrowness: all records from a single province/species of plant; cannot generalize across the species' range or other host plants Geographic/host narrowness

Interpretation & alternative explanations

• Secondary robbing plausibly occurs when primary robbers create holes; photographic verification plus photographer confirmation supports this mechanism in two cases Secondary robbing mechanism
• Energetic or handling efficiency hypotheses cannot be evaluated from current data; authors note that bees sometimes obtain energetic benefits from robbing but report no avian analogs — new data would be required Energetic efficiency unknown
• Predation‑risk reduction is a reasonable hypothesis but untested; alternative drivers include local nectar availability, competition avoidance, or opportunistic feeding on pre‑made holes — none are excluded by present evidence Alternative drivers and speculation

Suggested next steps (concise, actionable)

1. Standardized field observations at multiple sites tracking: (a) frequency of robbing vs legitimate feeding, (b) presence/absence of primary robbers, (c) time per flower visit, and (d) predator‑encounter rates during different feeding modes.
2. Experimental manipulations: create artificial robbing holes in matched flowers and compare hummingbird visit duration, nectar extracted, and predator approach rates to intact flowers.
3. Automated camera traps and radio/accelerometer tags on a sample of E. ensifera to quantify behavior, head‑exposure, and escape performance metrics during foraging bouts.

The paper is a short, well‑focused natural‑history note with photographic evidence; it is novel (first documented case), but low sample size and lack of behavioral quantification limit mechanistic inference — the paper's value is to document a credible counterexample to the assumption that only short‑billed hummingbirds rob nectar, and to motivate targeted field experiments.