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Matthijs Hollanders

@matthollanders.bsky.social

507 followers 271 following 245 posts

Quantitative ecology, statistics, wildlife, field herping. Post-doctoral Research Fellow @ U of Canberra Consultant @ Quantecol, quantecol.com.au Wildlife tour guide @ Australian Wildlife Encounters, www.australianwildlifeencounters.com

Posts Replies Media

Matthijs Hollanders @matthollanders.bsky.social · 29/08/2026

Epic few days finding wildlife in the Top End.

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Matthijs Hollanders @matthollanders.bsky.social · 01/08/2026

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Matthijs Hollanders @matthollanders.bsky.social · 01/08/2026

Anyone ever use the geometric Poisson distribution? If I've implemented it correctly in Stan, it's giving me better fits than negative binomial according to PSIS-LOO-CV with a big count occupancy model.

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Matthijs Hollanders @matthollanders.bsky.social · 02/07/2026

Yes.

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Matthijs Hollanders @matthollanders.bsky.social · 02/07/2026

Wonder if something like this could work. STZ happening on the pre-ordered offsets might be sufficient for identifiability. Then multiply the ordered offsets by the scales.

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Matthijs Hollanders @matthollanders.bsky.social · 01/07/2026

All of this with hierarchical individual-level parameters (with stz vectors), which was the primary motivation. The model will shine with within-chain parallelisation over individuals. See this for ecological diffusion/Rayleigh step lengths, permitting unequal intervals. doi.org/10.1186/s404...

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Matthijs Hollanders @matthollanders.bsky.social · 06/06/2026

Probably something to do with this.

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Matthijs Hollanders @matthollanders.bsky.social · 14/04/2026

occARU accommodates site-level predictors for occupancy and detection and additionally site-by-survey level predictors for detection rates. Continuous, categorical, and ordinal predictors are currently supported. Model complexity is handled via global-local shrinkage priors. 4/n

Figure produced by occARU::plot_partitions(fit). Shows variance partitions or component-level scales produced by simplex decomposing the variance of the detection (and potentially occupancy) linear predictor.

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Matthijs Hollanders @matthollanders.bsky.social · 14/04/2026

occARU takes in standardised CamtrapDB data by default, optionally thins detections with a user-specific value, and aggregates observations to surveys of arbitrary lengths. This balances temporal resolution with computational demands. 3/n

Figure produced by occARU::plot_surveys(fit), showing temporal detection rates for each species.

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Matthijs Hollanders @matthollanders.bsky.social · 14/04/2026

occARU uses hierarchical multispecies Gaussian processes to infer spatial and temporal variation in detection rates, and estimates interspecific correlations in these processes. These effects are orthogonally projected to retain inference on fixed effects. 2/n

Figure produced by occARU::plot_sites(fit), showing a map site locations shaped by occupancy status and sized by detection rates for each species.

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Matthijs Hollanders @matthollanders.bsky.social · 29/05/2025

I can’t stand that online journals can’t format equations properly.

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Matthijs Hollanders @matthollanders.bsky.social · 17/03/2025

Working on a multisite/multistate/robust design Jolly-Seber model in Stan where I need to marginalise (1) the entry occasion of each individual and (2) the sub-area within each site where each individual enters. 😮‍💨

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Matthijs Hollanders @matthollanders.bsky.social · 07/01/2025

I've been looking at different parameterisations of multi-season occupancy models, and it seems that dynamic (with colonisation and emigration) and auto-logistic models aren't all that different. Auto-logistic might be preferred with \alpha being a sort of average log odds. @masonfidino.bsky.social

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Matthijs Hollanders @matthollanders.bsky.social · 01/01/2025

I’ve been enjoying a restful Christmas break, and one of the highlights was this python selecting a carefully placed tin stack to lay her eggs.

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Matthijs Hollanders @matthollanders.bsky.social · 17/11/2024

It’s hard to beat an afternoon of herping our Gondwana rainforests. Big coastal carpet python under tin and a gravid snake-tooth skink on the crawl were amongst the many finds over the weekend.

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