We were feeling great!

Then, an astute reader pointed out a bit of data that didn’t make sense to them, and contacted us to ask for clarification. Specifically, the reader found that our reported “cost of transport” values, the energy cost per meter traveled, didn’t seem realistic to them. We checked the data and confirmed that they were correct! What we had reported as cost of transport were, in fact, an erroneously copied set of values that were the calculated oxyjoule equivalent metabolic rates when walking or running at a given speed.

So, we did what every research team should do, we set out to correct that mistake. The correction was published in August 2025 here. In some cases, when honest mistakes are made and erroneous data or findings are published, the resulting fix warrants a full retraction of the article (most obvious in cases where the key findings are undermined or invalidated following investigation). In other cases, such as in this one, we felt that the erroneous data were not central to the main findings of the research. Therefore, a correction seemed sufficient in this case.

It might be easy to assume that all I (or the rest of the team) feel after this process is embarassment, regret, and/or shame. And, I do regret having made the mistake…of course. But, in this day and age, I am choosing to be very proud of the fact that we acted as quickly as we could to correct that mistake and ensure the published data were as accurate as they could be. This ability for ourselves and our fields to find, understand, and correct our mistakes is what makes for “gold standard science”.

If anyone says they NEVER (or even infrequently) make mistakes, they are lying. Humans, even researchers and scientists, are fallable. We can at least choose to learn from these mistakes and, where possible, rectify them.

Sometime on April 24th, 2025, from the Lamanai Outpost Lodge where he is working with an international team to trap and study bats at the moment, Phil Oelbaum uploaded the corrected version of his PhD thesis to the University of Toronto School of Graduate Studies. Upon doing this, and the iminment publication of the thesis in T-Space, he will officially be Dr. Phil Oelbaum, PhD!

Phil’s thesis is titled, “Niche Occupancy, Partitioning, and the Role of Trophic Flexibility in Coexistence of Neotropical Bats.” Here is the abstract (in case you’re curious):

Understanding niche occupancy of an organism is critical to understanding its role in the environment, and how it persists as compared to others. In animal studies, the trophic niche is often used as a simplification of the Hutchinsonian realized niche. Trophic flexibility is a common strategy throughout the natural world to cope with various ecological and physiological challenges. Animals face fluctuations in resource availability, both inter- and intraspecific competition, and periods when nutrition is critical to meet metabolic demand. Bats, typically grouped together within trophic guilds, exhibit an exceptional amount of trophic flexibility and omnivory across faunas, particularly phytophagous species. The goal of my dissertation is to understand how ecological forces shape niche occupancy among diverse communities of bats, and to better understand how trophic flexibility enables niche occupancy, partitioning, and coexistence among these animals. I examined trophic flexibility through an ecological lens using stable isotope analysis. I examined individual specialization within populations, population-level responses to seasonal change, and community-level responses to species richness across sites. I found that individuals with preferences for food items or foraging locations are consistently preserved in isotopic values of their tissues over multiple time points, and this is widespread among Neotropical species. Seasonal comparisons revealed that trophic flexibility enables niche partitioning within season, as well as across seasons as more omnivorous species experience niche expansion, and population overlap decreases substantially from one season to another. More speciose communities demonstrated greater niche packing, while we found limited evidence to suggest that community niche space increases, populations of some species may increase niche breadth when more heterospecifics are present. I also examined how dietary protein impacts the metabolically intensive process of wound healing in the Jamaican fruit bat in an experimental study where I caused mechanical injuries to the flight membranes of captive individuals. Though there was no significant effect of a protein enriched diet on the rate of healing, there was indication that the group fed the experimental diet had improved healing outcomes than those fed a control diet. Trophic flexibility plays a key role in maintaining coexistence among bats.

Congratulations to Phil! We will share a toast upon his return to Toronto!

As an annual tradition, The Royal Society, publishers of such journals as Proceedings B and Biology Letters, names the 10 most popular papers they publish each year. The Welch Lab paper led by Dr. Giulia Rossi is #9 on that list!

From the announcement:

9. Vampire bats get their energy from an unusual source

This Biology Letters paper found that vampire bats are able to burn amino acids as a fuel source, in a similar way to blood-sucking insects. In the study, researchers coaxed vampire bats in their lab to run on a treadmill as a way to measure their metabolism. Sensors monitored oxygen intake and carbon dioxide released in the bat’s breath, while the source of the energy for respiration was determined using isotopically labelled cow blood. The results revealed that the vampire bats were using amino acids for energy, rather than carbohydrates or fats, which derive from the digestion of proteins and are a common component in blood.

In this study, Natalia identified several biomarkers that reliably reflected pesticide exposure in a captive group of bats at McMaster University in Hamilton, ON. She then employed these same biomarkers in several populations of wild bats in the tropics that likely experienced differing levels of pesticide exposure (because they roosted in caves nearer, or farther away, from crops), and was able to show that the same biomarkers were both easy to collect and analyze (e.g. simple blood-smear based assays) and were of diagnostic utility.

Congrats to Natalia and all the co-authors!

Congratulations to Welch lab PhD student Phillip Oelbaum on being named a 2024 Student Scholar by Bat Conservation International for his project, entitled “Foraging and roosting ecology of Phyllonycteris aphylla in Jamaica.”

More about Phil’s project (from the BCI page):

The Jamaican flower bat, Phyllonycteris aphylla, is listed as critically endangered and until now was only known from Stony Hill Cave. In March-April 2023, we surveyed seven caves throughout Jamaica, most known to have historically had colonies of P. aphylla, and at two of these sites (Green Grotto Caves and Rock Spring Caverns), we found both male and pregnant female individuals of this important species. Both new sites are substantially larger systems than Stony Hill, but with little of Green Grotto’s roosting space explored and no previous bat work being conducted at Rock Spring, relatively little is known about these communities as compared to other caves throughout Jamaica (e.g., Windsor, St. Clair Cave).

Based on observations of the Jamaican Caves Organisation, Rock Spring is believed to be one of the largest bat communities on the island, despite temperatures internally being between 23-24⁰C in all documented roosting chambers. We intend to begin a roost temperature monitoring program to better understand areas of importance within these caves to better protect them and also understand possible fluctuations in population between chambers and possible movement between caves. Furthermore, we intend to seek out new caves that P. aphylla may be present in. Collecting patagium and hair from P. aphylla and heterospecifics for stable isotope analysis will provide critical ecological data to alert us to areas of importance outside the caves and critical habitat for this species.

Following a successful first field-trip in early 2023 resulting in a publication on two new breeding populations of the endangered Jamaican flower bat (Phyllonycteris aphylla), Phil Oelbaum and Jerrica Jamison, joined collaborator Damian Whyte and the Jamaica Caves Organization for more censusing of Jamaican “rat bats”!

I anticipate recruiting up to 1 MSc student and 1 or 2 PhD students (i.e. student already has MSc or is a BSc graduate that is especially competitive). In particular, I am looking for students interested in studying a) ecotoxicology and/or ecoimmunology of neotropical bats and birds, b) digestive physiology and ecology, c) comparative animal energetics, and/or d) the interface of diet, natural history, and aging/senescence. Of course, the lab welcomes compelling projects outside of these areas as well, provided it is a mutually-agreed “good fit”.

The positions are fully-funded by a Welch Lab NSERC Discovery Grant and Discovery Accelerator Supplement. Domestic and particularly strong international candidates are invited to apply.

Students are welcomed to apply through either the Cell & Systems Biology or Ecology & Evolutionary Biology graduate programs. More details about graduate school at the University of Toronto, including information on stipends and more on how to apply, can be found here.

In addition to applying through the Graduate School (the official route to apply), interested students should e-mail me the following:

1. A CV/resume
2. An unofficial copy of their undergraduate (and graduate, if applicable) transcript
3. A cover letter summarising their experience and interests
4. A list of 2-3 academic/research mentors (with contact info.) that can provide recommendations, if contacted

The Welch lab embraces EDI principles outlined in UTSC’s Strategic Plan: Inspiring Inclusive Excellence. We are fully committed to a lab community that embraces and welcomes all forms of diversity, strives for excellence in our research and professional interactions, and recognizes and actively supports wellness in our team members.

A newly published paper led by recent MSc graduate Raafay Syed Ali has been featured in “Inside the JEB”

It seems there is no limit to hummingbird superpowers. Blessed with the manoeuvrability of insects and high-speed vision, the nimble birds fuel their whirlwind lifestyle with a diet of sugar-charged nectar. Yet, by night, the animals wind down their metabolism, resorting instead to burning fat. Knowing that the birds must switch their metabolism back in the blink of an eye after their first morning sip of nectar, Ken Welch and Raafay Sayed Ali from the University of Toronto Scarborough, Canada, wondered how the frenetic creatures manage the feat. They explain that mammals depend on a pool of sugar-transporting proteins, known as GLUTs, to maintain the delicate balance between the sugar in their blood and cells. However, hummingbirds lack one essential transporter, GLUT4, which is key for humans and other mammals to regulate their bodies’ sugar use. Intrigued by the birds’ unconventional sugar-charged way of life, Ali, Morag Dick and Welch decided to monitor which GLUTs the birds depend on and where they are produced in the body to learn more about how they manage their sugar levels.

https://jeb.biologists.org/content/223/20/jeb237800