Extreme uncertainty and unquantifiable bias do not inform population sizes

Robinson, Orin J.; Socolar, Jacob B.; Stuber, Erica F.; Auer, Tom; Berryman, Alex J.; Boersch‐Supan, Philipp H.; Brightsmith, Donald J.; Burbidge, Allan H.; Butchart, Stuart H. M.; Davis, Courtney L.; Dokter, Adriaan M.; Giacomo, Adrián S. Di; Farnsworth, Andrew; Fink, Daniel; Hochachka, Wesley M.; Howell, Paige E.; Sorte, Frank A. La; Lees, Alexander Charles; Marsden, Stuart J.; Martin, Robert W.; Martin, Rowan O.; Masello, Juan F.; Miller, Eliot T.; Moodley, Yoshan; Musgrove, Andy J.; Noble, David G.; Ojeda, Valeria; Quillfeldt, Petra; Royle, J. Andrew; Ruiz‐Gutiérrez, Viviana; Tella, José Luis; Yorio, Pablo; Youngflesh, Casey; Johnston, Alison

doi:10.1073/pnas.2113862119

Cited by 18 publications

(13 citation statements)

References 7 publications

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“…While parrots have been traditionally considered as seed predators (Toft and Wright, 2015), recent studies have described multiple examples across the world of parrots legitimately dispersing several plant species through epizoochory, endozoocory, and stomatochory (Tella et al, 2015;Blanco et al, 2018;Hernández-Brito et al, 2021) as well as transferring pollen (i.e., acting as pollinators) after feeding on conifer cones or flowers (Fleming and Muchhala, 2008;Gleiser et al, 2017), thus challenging this paradigm. Parrots are among the richest avian orders (c. 400 extant species) and, although several species have decreasing populations in their native ranges (e.g., Olah et al, 2016;Berkunsky et al, 2017), they are still rather abundant compared with other taxa (Callaghan et al, 2021; but see Robinson et al, 2022 for caution on population estimates). This, in addition to their generalist diets and plastic feeding behaviors (Renton et al, 2015;Toft and Wright, 2015), may explain the pervasiveness of parrotplant interactions, involving not only native but also exotic parrot and plant species.…”

Section: Introductionmentioning

confidence: 99%

Worldwide Distribution of Antagonistic-Mutualistic Relationships Between Parrots and Palms

et al. 2022

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Palms, like all plants, show coevolutionary relationships with animals that have been traditionally categorized as mutualistic (seed dispersers and pollinators) or antagonistic (seed predators). This dual perspective, however, has prevented a full understanding of their true interactions with some animal groups, mainly those that do not ingest entire fruits. One clear example is parrots, which have been described to use palm species as feeding resources, while their role as seed dispersers has been largely neglected. Here, we combined fieldwork data with information from the literature and citizen science (i.e., naturalists and nature photographers) on parrot foraging ecology worldwide to evaluate the spatial and taxonomic extent of parrot-palm interactions and to identify the eco-evolutionary factors involved. We identified 1,189 interactions between 135 parrots and 107 palm species in more than 50 countries across the six realms where palms are present as natives or introduced. Combining this information, we identified 427 unique parrot-palm interacting pairs (i.e., a parrot species interacting with a palm species). Pure antagonistic interactions (i.e., parrots just preying on seeds or eating or destroying their non-reproductive parts) were less common (5%) than mutualistic ones (i.e., parrots benefiting by partially preying on the seed or fruit or consuming the pulp of the fruit or the flower but also contributing to seed dispersal and, potentially, pollination; 89%). After controlling for phylogeny, the size of consumed seeds and parrot body mass were positively related. Seed dispersal distances varied among palm species (range of estimated median dispersal distances: 9–250 m), with larger parrots dispersing seeds at greater distances, especially large fruits commonly categorized as megafauna anachronisms (>4 cm length). Although parrot-palm interactions are widespread, several factors (e.g., social behavior, predation fear, food availability, or seasonality) may affect the actual position of parrots on the antagonism-mutualism continuum for different palm species and regions, deserving further research. Meanwhile, the pervasiveness of parrot-palm mutualistic interactions, mainly involving seed dispersal and pollination, should not be overlooked in studies of palm ecology and evolution.

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Section: Introductionmentioning

confidence: 99%

Worldwide Distribution of Antagonistic-Mutualistic Relationships Between Parrots and Palms

et al. 2022

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“…The standard deviation of the global abundance distribution became grossly exaggerated under the sort-then-sum procedure, with a median of 50 billion, a mean of 431 billion, and a range of 256 trillion ( Fig 5b ). This degree of uncertainty will render the estimates for global abundance useless in many conservation contexts, as was noted by critics [ 40 ].…”

Section: Discussionmentioning

confidence: 99%

“…Earlier concern regarding Callaghan et al’s [ 19 ] methodologies, however, focused on the acutely uncertain and often biased constituent distributions modeling individual species’ abundance [ 40 , 41 ]. Our analysis identifies an important and previously unrecognized driver of uncertainty in their final distribution for global bird abundance (the sort-then-sum procedure), and we have found that alternative approaches result in distributions for global bird abundance with dramatically lower uncertainty.…”

Section: Discussionmentioning

confidence: 99%

Difficulties in summing log-normal distributions for abundance and potential solutions

2023

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The log-normal distribution, often used to model animal abundance and its uncertainty, is central to ecological modeling and conservation but its statistical properties are less intuitive than those of the normal distribution. The right skew of the log-normal distribution can be considerable for highly uncertain estimates and the median is often chosen as a point estimate. However, the use of the median can become complicated when summing across populations since the median of the sum of log-normal distributions is not the sum of the constituent medians. Such estimates become sensitive to the spatial or taxonomic scale over which abundance is being summarized and the naive estimate (the median of the distribution representing the sum across populations) can become grossly inflated. Here we review the statistical issues involved and some alternative formulations that might be considered by ecologists interested in modeling abundance. Using a recent estimate of global avian abundance as a case study (Callaghan et al. 2021), we investigate the properties of several alternative methods of summing across species’ abundance, including the sorted summing used in the original study (Callaghan et al. 2021) and the use of shifted log-normal distributions, truncated normal distributions, and rectified normal distributions. The appropriate method of summing across distributions was intimately tied to the use of the mean or median as the measure of central tendency used as the point estimate. Use of the shifted log-normal distribution, however, generated scale-consistent estimates for global abundance across a spectrum of contexts. Our paper highlights how seemingly inconsequential decisions regarding the estimation of abundance yield radically different estimates of global abundance and its uncertainty, with conservation consequences that are underappreciated and require careful consideration.

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“…Inconsistency in data collection is also possible due to inconsistent searching efforts, where animal owners may not be checking their animals regularly and opportunistically collecting arthropod vectors. A major benefit of working with animal owners in the general public is that there is the potential for a large sample size, but this may also introduce biases if a large percentage of samples comes from one region [ 53 ]. Analyses should therefore account for population size and geographic location when conducting studies on the prevalence of vectors and/or vector-borne pathogens using citizen scientist-collected data.…”

Section: Personal Companion Animal Accessmentioning

confidence: 99%

All for One Health and One Health for All: Considerations for Successful Citizen Science Projects Conducting Vector Surveillance from Animal Hosts

Poh

Evans

Skvarla

et al. 2022

Insects

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Many vector-borne diseases that affect humans are zoonotic, often involving some animal host amplifying the pathogen and infecting an arthropod vector, followed by pathogen spillover into the human population via the bite of the infected vector. As urbanization, globalization, travel, and trade continue to increase, so does the risk posed by vector-borne diseases and spillover events. With the introduction of new vectors and potential pathogens as well as range expansions of native vectors, it is vital to conduct vector and vector-borne disease surveillance. Traditional surveillance methods can be time-consuming and labor-intensive, especially when surveillance involves sampling from animals. In order to monitor for potential vector-borne disease threats, researchers have turned to the public to help with data collection. To address vector-borne disease and animal conservation needs, we conducted a literature review of studies from the United States and Canada utilizing citizen science efforts to collect arthropods of public health and veterinary interest from animals. We identified common stakeholder groups, the types of surveillance that are common with each group, and the literature gaps on understudied vectors and populations. From this review, we synthesized considerations for future research projects involving citizen scientist collection of arthropods that affect humans and animals.

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Extreme uncertainty and unquantifiable bias do not inform population sizes

Cited by 18 publications

References 7 publications

Worldwide Distribution of Antagonistic-Mutualistic Relationships Between Parrots and Palms

Worldwide Distribution of Antagonistic-Mutualistic Relationships Between Parrots and Palms

Difficulties in summing log-normal distributions for abundance and potential solutions

All for One Health and One Health for All: Considerations for Successful Citizen Science Projects Conducting Vector Surveillance from Animal Hosts

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