Wednesday, February 19, 2025

In Denmark, rural cat owners are neutering their cats and allowing them indoor access

From 1998 to 2022, there were fewer farm and outdoor-only cats, and more neutered, microchipped pets with indoor access

PLOS

Changes in management of owned cats in the countryside – A comparison of results from surveys undertaken in the same rural area of Denmark in 1998 and 2022 — image:
A cat prowling outside. According to the new study, cat owners in the Denmark countryside are increasingly managing their cats in the same way as urban cat owners, resulting in fewer unwanted kittens being born.
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Credit: miezekieze, Pixabay, CC0 (https://creativecommons.org/publicdomain/zero/1.0/)

Cat owners in the Denmark countryside are increasingly managing their cats in the same way as urban cat owners, resulting in fewer unwanted kittens being born, according to a study published February 19, 2025, in the open-access journal PLOS One by Peter Sandøe from the University of Copenhagen, Denmark, and colleagues.

Populations of unowned domestic cats – whether unsocialized feral cats that have never lived with humans, or socialized cats that have strayed or been abandoned – are regarded as problematic in many countries. It is argued that they are a nuisance, that they transmit disease to humans, owned cats and wildlife, that the unowned cats suffer from poor welfare, and that their hunting reduces biodiversity. There is therefore wide agreement that populations of unowned cats should be controlled.

Interestingly, a recent study in Denmark documented a low number of unowned cats, probably due to a drop in their number over recent years. Sandøe and collaborators set out to investigate whether this could be explained by changes in the ways rural cat owners, in Denmark at least, have managed and cared for their cats over time. Households in a 47 km2 countryside area in Western Zealand, and on 23 farms near this area, were presented with the same questionnaire in 1998 and in 2022.

Over this period, there was a major shift away from cats living on full-scale farms, where the number of cats decreased by two-thirds, and on hobby farms, where the number halved. However, the number of cats living in residential homes nearly doubled, and, correspondingly, there was a significant increase in the proportion of cats with indoor access.

In addition, cat owners have increasingly adopted measures to manage their cats, including much higher proportions of cats being spayed and castrated. There was an increase from 61% to 98% among male cats with indoor access and from 13% to 70% among male cats without indoor access. There was also a major increase in cats that have been earmarked or microchipped and registered, rising from 8% to 64%. This change in owner behavior has led to many fewer unwanted kittens being born and subsequently killed.

According to the authors, the findings reflect both a diminishing divide between rural and urban life in a small and highly industrialized country and a growing human attachment to owned cats. The study also helps to explain why the number of unowned cats in Denmark recently has been found to be much lower than previously assumed.

The authors add: “The study provides evidence of changing rural human-cat relationships, with rural cat owners increasingly managing cats in the same way as urban cat owners. This probably reflects both a diminishing divide between rural and urban life in a small and highly industrialized country like Denmark and a growing human attachment to owned cats.”

In your coverage, please use this URL to provide access to the freely available article in PLOS One: https://plos.io/4gA4GH2

Citation: Sandøe P, Gade U, Ujvári ML, Wöhler B, Lund TB, Meilby H, et al. (2025) Changes in management of owned cats in the countryside – A comparison of results from surveys undertaken in the same rural area of Denmark in 1998 and 2022. PLoS ONE 20(2): e0316704. https://doi.org/10.1371/journal.pone.0316704

Author countries: U.S., Denmark

Funding: This study was supported by Animal Welfare Denmark and Aage V. Jensens Fonde in the form of grants awarded to MLU, by Kitty og Viggo Freisleben Jensens Fond by grants awarded to BW and UG, and by Skibsreder Per Henriksen, R. og Hustrus Fond by a grant awarded to PS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Journal

PLOS One

DOI

10.1371/journal.pone.0316704

Method of Research

Survey

Subject of Research

Not applicable

Article Title

Changes in management of owned cats in the countryside – A comparison of results from surveys undertaken in the same rural area of Denmark in 1998 and 2022

Article Publication Date

19-Feb-2025

COI Statement

Marianne Lund Ujvári worked for Animal Protection Denmark while doing the first part of the project in the late 1990s. The remaining authors have declared that no competing interests exist. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

University of Hawai’i researchers discover 10 new sponge species in Kāneʻohe Bay

University of Hawaii at Manoa

Colorful sponges — image:
Colorful organisms collect on autonomous reef monitoring stuctures (ARMS). Stelletta hokuwanawana is among the 10 species of newly discovered marine sponge.
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Credit: Rachel Nunley, Kaloko-Honokōhau National Historical Park.

In a succession of breakthrough studies published this week and last month in the journals PeerJ and Zootaxa, researchers at Hawai’i Institute of Marine Biology (HIMB) Toonen-Bowen (ToBo) Lab, using a technique that explores both genes and structural characteristics, have introduced 10 new species of marine sponge. Despite their distinction as one of Earth’s oldest lifeforms and the key role they play in sustaining coral reef ecosystems, marine sponges are vastly understudied.

Kāne’ohe Bay, where HIMB is located and the research was conducted, is abundant with small, isolated “patch reefs,” which are teeming with undescribed sponge species as well as non-native species introduced from the Caribbean and the Western Indo-Pacific. These findings contribute to a broadening understanding of sponge biodiversity within the Hawaiian archipelago and throughout Oceania.

“We used autonomous reef monitoring structures (ARMS) to collect sponges from within the reef,” explains Rachel Nunley, a Scientists in Parks (SIP) Intern at Kaloko-Honokōhau National Historical Park and lead author of the PeerJ study in which 6 new sponge species were identified. “These structures mimic the reefʻs cryptic environment, allowing us to observe and document the species without causing harm to the surrounding reef. After sponge collection, we used DNA to narrow down what species we were looking at. Then we dug into the literature to see if these sponges existed anywhere else in the world. I created a database and compared characteristics to find the closest relatives. Through this integrative taxonomic approach, we found that these species found in Kāneʻohe Bay were new to science and have not been documented anywhere else in the world.”

Sponges are notoriously difficult to study, for a variety of reasons.

“Sponges are found within the ‘nooks and crannies’ of the reef, making them difficult to collect without destroying the reef,” shares Jan Vicente, a ToBo Lab post-doctoral researcher and lead author on the Zootaxia article, in which four new sponge species were detected. “Sponges are also very small and fragile, with very limited morphological characters which make identification difficult with the unaided eye. The sponge community within these cryptic spaces is also highly dynamic, because sponges have a lifespan of only two months! One month they are present, and they can be gone the next. These are all reasons why we have yet to fully understand the complex diversity of sponges and other metazoans deep within the reef matrix.”

“Taxonomy is tedious!” adds Nunley. “It involves every tiny detail. Missing a detail can change your species entirely. But the challenges make it that much more rewarding, and taxonomy is so much more than just describing species. It involves creating detailed visual representations of species, engaging with and collaborating with local communities, and contributing valuable information to the scientific community.”

The grueling work more than paid off, and detecting so many previously unknown species in the patch reefs that surround their island-based laboratory surprised the research team.

“Previous assessments of sponge diversity in Kāneʻohe Bay have totaled only around 30 sponge species in the bay,” notes Vicente. “But these earlier studies did not target the nooks and crannies of the reef. The coral reef of Moku o Loʻe surprises us daily with how little we know about its biodiversity. After decades of research on this patch reef, we have yet to reach a full understanding of its sponge biodiversity.”

As the ocean changes and coral reefs face unprecedented threats, it is critical to understand coral reef ecosystem dynamics. Sponges play a central role in regulating and sustaining these systems.

“Sponges are widely underappreciated, even though they play an essential role in cycling nutrients that help maintain coral reef biodiversity in remote island archipelagos where nutrients in coral reefs are scarce,” emphasizes Vicente. “Discovering such a remarkable diversity of these ecologically important species sheds light on their role in nutrient cycling.”

When tasked with naming the new sponge species, the research team selected names that honor either the mo'olelo of Moku o Loʻe or the ʻŌlelo Hawaiʻi to depict diagnostic characters for each of the species.

“Many of the species we found are new to science,” explains Principal Investigator of the ToBo lab and co-author on both studies, Robert Toonen. “They were found in Kāneʻohe Bay off the island of Moku o Loʻe, and their names come from Native Hawaiian stories. “Lo‘e,” for example, “was the sister of three brothers who kept honesty within the family.”

Toonen adds that these findings are likely the first of many to come. The research team has sampled over 1000 specimens from the coral reef cryptic fauna using ARMS in Kāneʻohe Bay, and they have also recovered ARMS from five different ecoregions across the Pacific. In time, they hope to understand the complete diversity of Oceania. They want to determine which species are endemic, native, and which have been introduced to the Hawaiian Archipelago, and they want to learn how the species are connected biogeographically.

A closer look at the newly described marine sponge species, stelletta hokuwanawana, whose name is derived from two Hawaiian words: hōkū (star) and wanawana (spiny or thorny), translating to “thorny star.” This name was chosen to reflect the spiky microscleres in this species.

Credit

Jan Vicente, HIMB.