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Deer in the Woods

Conservation & Research

Scientific Papers

Passerine birds in zoos: A global approach on distribution patterns and conservation breeding of threatened birds in zoological institutions (Wahle et al., 2024)

January 2024

A paper in Journal of Zoo Aquarium Research looked into the representation of passerine birds across zoos, using data from the Zoological Information Management System (ZIMS):

44,394 individuals of 408 passerine bird species currently represented in ZIMS institutions.

34 of those species (4.1%) are listed as threatened in the IUCN Red List, with an additional 2.7% Near Threatened.

Over a quarter of threatened species are held by only one zoo.

Under a quarter of all kept passerine species bred between November 2020-2021.

✔Zoos should move towards increased representation of threatened species in their collections and improve collaborations in conservation breeding programmes.

A Review of Two Decades of In Situ Conservation Powered by Public Aquaria (Correia et al., 2024)

February 2024

The 150 members of the European Union of Aquarium Curators (EUAC) have worked together to provide a substantial contribution to in situ conservation over the last two decades:
✔Since 2004: Over €250,000 awarded to conservation projects.
49 projects in over 20 countries were supported. 
✔Nearly 70% of projects secured additional funding and resources to expand.
✔Half of projects produced multiple scientific publications.
Community education was a key aim of many of these projects.

Tagging and location preferences to inform post-release monitoring of the Greater Bermuda land snail Poecilozonites bermudensis (Flewitt et al., 2023)

July 2023

A novel method for Bermuda land snail identification through tagging (Alpha fluorescent tags glued to sanded and non-sanded shells) was tested in a new study in the JZAR:
✔Tag loss and snail survival monitored in 400 captive snails,, over six months.
✔Tag method was successful (0% tag loss).
Sanding of shells was not necessary, and affected survival.
Environmental conditions affected snail behaviour, and should be considered when monitoring them in the wild.
✔Applications to post-release monitoring of reintroduced snails.

First successful head-start program of leatherback sea turtles (Dermochelys coriacea) in Thailand and proposed dietary strategy (Kanghae et al., 2023)

August 2023

A protocol for head-starting programmes of leatherback sea turtles was proposed in a new paper in Zoo Biology:
Fifteen newly hatched turtles randomly harvested from each of two nests from the same female.
✔Group from one nest hatched at the bottom of egg chamber - 13.3% survived by the end of the programme.
✔Group from the other nest hatched at the top of egg chamber - 46.7% survived by end of the programme.
✔Most deaths were caused by accidents and infections.
New diet proposed - an improved diet, modified water supply and pond systems might improve survival in captivity before they are released back into the wild.

Maximizing the potential for living cell banks to contribute to global conservation priorities
 (Mooney et al., 2023)

June 2023

A study in Zoo Biology evaluated the conservation potential of cryobanks, and how to maximise it:
San Diego Zoo Wildlife Alliance Frozen Zoo® living cell collection analysed.
Qualitative framework implemented to prioritise species for future sampling.
965 species in collection - 5% of all listed threatened species in the IUCN Red List.
✔Potential to sample 707 more threatened species from existing zoo & aquarium collections - would increase representation to 16.6%.
✔Challenges & opportunities discussed in paper, as well as species with high priority for sampling.

The fate and movements of aquarium-released giant trevally Caranx ignobilis inferred from acoustic telemetry  (Mann et al., 2023)

April 2023

The movements of four giant trevally, released into the wild after eight years in an aquarium exhibit, were tracked with acoustic telemetry:
Wild-bred individuals that were caught as juveniles, but stayed on display in the aquarium for eight years.
✔Two individuals lived for at least six years post-release, adopted the movements of their wild counterparts & joined them at spawning aggregation sites.
✔The other two individuals were not detected after a few months in the wild.
✔Despite years in ex situ settings, evidence suggests successful adaptation to the natural environment.

By Bits and Pieces: The Contributions of Zoos and Aquariums to Science and Society via Biomaterials (Powell, Meyer & Duncan, 2023)

March 2023

The contributions of zoos and aquariums to science also include the provision of biomaterials to research projects, as highlighted by a paper in JZBG:

✔Data from 10 AZA-accreditted institutions.
✔An average of 138.5 biological samples provided per year.
Feces and blood/serum were the most common type of samples requested.
✔Over half of the institutions had stored samples available for research.

Multi-sensor biologgers and innovative training allow data collection with high conservation and welfare value in zoos
 (English et al., 2023)

January 2023

A paper in Journal of Zoo & Aquarium Research described the potential of animal-attached loggers (i.e. biologgers) for conservation, behaviour and welfare research:
✔Four zoo-housed African wild dogs were fitted with tri-axial accelerometer and magnetometer loggers: two were sedated, two were trained to accept the collars. 
✔Biologger data allowed the detection of individual differences in the recovery from sedation, as well as activity patterns in relation to feeding regimes.
Higher energy expenditure in days with pony carcass feeding than rabbit feeds, but it varied between the days they were fed meat pieces.
✔Biologgers can be used to collect data with welfare and conservation value, and training can help reducing the need for sedation when fitting the devices.

Extinct in the wild: The precarious state of Earth’s most threatened group of species (Smith et al., 2023)

February 2023

A new study published in Science reviewed the fates of the 95 species that, since 1950, remained only in ex situ facilities, zoos and aquariums included, after they have gone extinct in the wild:
12 recovered wild status thanks to collaborative conservation efforts.
11 have been lost while in human care.
41 have not yet been subject to reintroduction efforts.
Ex situ challenges: Low population numbers & genetic diversity.
✔More focus is needed, with collaborative conservation actions, to return the remaining EW species to their natural environment.

The Societal Value of the Modern Zoo: A Commentary on How Zoos Can Positively Impact on Human Populations Locally and Globally (Greenwell et al., 2023)

January 2023

A review now out in JZBG, co-authored by our very own Ricardo, explored the benefits of modern zoos and aquariums to human societies. Evidence is provided on how zoos, with their four main aims - Conservation, Education, Research and Recreation (Engagement) - both directly and indirectly have positive impacts on human health and wellbeing, education, ethics and socio-economics. Areas in need of further work and evaluation are also highlighted!

Why Partner with a Zoo or Garden? Selected Lessons from Seventy Years of Regional Conservation Partnerships at the Arizona-Sonora Desert Museum)  (Colodner et al., 2022)

December 2022

The roles of zoos and botanical gardens in regional conservation partnerships are discussed in a new paper in JZBG, with examples from Arizona-Sonora Desert Museum:
Conservation advocates: ASDM-supported research & advocacy led to increased protection for islands in the Gulf of California;
Field research & long-term databases: establishment of a protected area & nearly 40 years of data on multiple native plants.
Community conservation: participation in the development of a conservation plan for the Sonoran Desert.
Ex situ conservation: ASDM manages insurance populations for several species, although current focus is on habitat restoration.
Conservation coordinators: ASDM plays a leading research & education role in a management programme for invasive grasses.

Bridging conservation across the ex situ-in situ spectrum: Insights into the reproductive ecology of the threatened narrow-headed gartersnake (Thamnophis rufipunctatus) (Blais et al., 2022)

December 2022

Zoo-housed animals can provide important insights into the ecology of their species. A paper in Zoo Biology explains how with examples from the narrow-headed gartersnake population housed at Phoenix Zoo:
✔Data analysed 2009-2018: courtship behavior, parity and litter size, offspring size, and neonatal growth.
✔Courtship & parturition seemed to be associated with North American monsoon season.
✔First records of iteroparity (i.e. multiple reproductive cycles) & entirely ex situ reproductive generations.
Litter sizes varied and related to maternal body mass.
✔Novel data with applications to in situ research and conservation.

A Guide for Successful Research Collaborations between Zoos and Universities (Schulz et al., 2022)

June 2022

Research collaborations between zoos and universities are vital for the advancement of zoo science, but how to ensure such collaborations are succesful? A paper in Integrative & Comparative Biology investigated:
117 staff from 59 US zoos surveyed.
Best practices for the different stages of these collaborations highlighted.
✔Collaborations jeopardised when university's personnel did not appreciate zoo staff's time constraints or the differences between zoo & lab animals.
✔Recommendations provided on how to build long-lasting successful collaborations.

Ex Situ Breeding Program with Wild-Caught Founders Provides the Source for Collaborative Effort to Augment Threatened New England Cottontail Populations 
(Brown & Puccia, 2022)

November 2022

A new paper in Journal of Zoological and Botanical Gardens describes the ex situ breeding programme for the vulnerable cottontail in New England, US:
Roger Williams Park Zoo was first zoo to breed the species.
✔Since 2010: 139 wild (founders) brought to the zoo for breeding, with over 600 kits born & over 250 released into the wild.
✔Several conservation partners involved in in situ efforts such as habitat restoration & protection.
Research conducted ex situ allows to further understand the behaviour of this species, which is difficult to observe in the wild.

Over 25 Years of Partnering to Conserve Chiricahua Leopard Frogs (Rana chiricahuensis) in Arizona, Combining Ex Situ and In Situ Strategies (Harris et al., 2022)

October 2022

A long-term conservation programme for the Chiricahua leopard frog has been described in a paper in JZBG:
✔Over 25-years old conservation programme by U.S. Fish and Wildlife ServicePhoenix Zoo & other partners.
✔Over 26,000 larvae, froglets, and adults, as well as 26 egg masses released into the wild.
Sites occupied by this species increased from 37 (2007) to 155 in last five years, thanks to integrated in situ & ex situ efforts.
Communication among partners has been vital for the success of the programme.
✔Species is still threatened, but collaborative programme has been a success so far.


Teamwork Makes the String Work: A Pilot Test of the Loose String Task with African Crested Porcupines (Hystrix cristata(Truax et al., 2022)

September 2022

The cooperative behaviour of a pair of African crested porcupines was tested in a study published in JZBG:
✔ African crested porcupines are cooperative breeders that mate for life, but can they cooperate in other tasks?
✔ Task: cooperatively pull ropes to reach a platform with rewards.
✔ Porcupines were successful at task but did not coordinate actions or solicited behaviours from partner. 
✔ Further research required to investigate their understanding of their partner's role in the task.

Five psychological principles of codesigning conservation with (not for) communities (Cranston et al., 2022)

August 2022

A paper in Zoo Biology discussed five principles to facilitate the co-designing of conservation programmes with communities:
✔The Five Factors of Sustained Engagement (Five Factors) psychometric instrument was used to assess two (zoo) community engagement projects;
✔The Five Factors can be used to increase community motivation to engage in conservation efforts in the long-term;
✔Psychology-based approach that can help assessing & improving community engagement in conservation projects.

Nursing behaviours of black rhinoceros Diceros bicornis in a zoological park: a case report (Nakamichi & Saito, 2022)

July 2022

A paper in JZAR looked into nursing behaviours of a zoo-housed female black rhino and her fourth and fifth calves:
✔Female accepted over half of the suckling attempts by the calves;
Fewer suckling bouts were terminated by the female than the calves;
✔Duration of suckling bouts increased with age;
✔Female showed considerable tolerance for the calves' nursing needs.

Resurrecting biodiversity: advanced assisted reproductive technologies and biobanking (Bolton et al., 2022)

July 2022

A review in Reproduction & Fertility explored the importance, use and challenges of cryobanking in wildlife conservation:
Cryopreservation of viable cells & tissues, followed by advanced assisted reproductive technology can rescue species from extinction & help ensuring their long-term survival;
✔These methods can increase genetic diversity in the population by bringing back lost genetics;
✔Currently focused on mammals, more taxa need to benefit from this approach;
Approaches and challenges further discussed.

The use of infrared thermography to noninvasively measure the surface temperature of polar bears during bouts of social play (Bissonnette, Waterman & Peterson, 2022)

July 2022

A paper in Zoo Biology measured the surface temperatures of the eyes of zoo-housed polar bears:
Differences between eye surface temperature & internal rectal temperature;

✔Mean eye temperature increased after social play (in comparison to baseline -  immobilised)  - indication of energy expenditure;

✔Thermal imagery may be a useful tool to investigate energy expenditure of captive and wild polar bears.

Primate cognition in zoos: Reviewing the impact of zoo-based research over 15 years (McEwen et al., 2022)

March 2022

A review in the American Journal of Primatology assessed the contributions of zoo-based research to the study of primate cognition, comparing it with other study sites:
 Zoo-based research accounts for 25% of the publications on the topic;
 Cognitive studies in zoos included a relatively high diversity of species;
 Diverse range of primate cognition topics researched in zoos;
 Zoos offer great opportunities for research in this area, and further collaborations between researchers are recommended.

Bridging the Research Gap between Live Collections in Zoos and Preserved Collections in Natural History Museums (Poo et al., 2022)

April 2022

A new paper in BioScience highlighted the need to encourage research collaborations between zoos and museums:

Collaborations between these two types of institutions are currently underdeveloped;
Potential for immediate collaborations: specimen & data transfer postmortem, permanent preservation of zoo animals and data in museums;
Zoo data should be integrated with other databases, and more easily accessible

Does Observer Presence Modify the Behavior and Enclosure Use of Captive Edwards’ Pheasants?
(Hoy & Brereton, 2022)

April 2022

A study in JZBG looked into the impacts of a quiet stationary observer (in comparison to camera observations) on the behaviour of captive Edwards' pheasants:
Resting & clustering increased;
Feeding & locomotion decreased;
Preening & standing not affected by observer (but affected by visitors and keepers);

Small effect on enclosure use also observed;

The "Observer effect" should be taken into consideration when developing behavioural studies.

Airborne environmental DNA for terrestrial vertebrate community monitoring (Lynggaard et al., 2022)

January 2022

A study in Current Biology tested whether enviromental DNA (eDNA) captured from air can be used to identify vertebrate communities:
Air filtered in three locations at Copenhagen Zoo;
Metabarcoding of airborne eDNA resulted in detection of 49 vertebrate species;
26 orders & 37 families: species kept at the zoo, species in the zoo's surroundings & species used as feed for the animals;
Increased chance of detection with higher biomass & if closer to air sampling device.
Applications to in situ research & monitoring of terrestrial communities.

Review of threatened Malagasy freshwater fishes in zoos and aquaria: The necessity of an ex situ conservation network - A call for action (Leiss et al., 2021)

December 2021

A paper in Zoo Biology highlighted the need for improved ex situ conservation efforts for Malagasy freshwater fish species:

79 freshwater species endemic to Madagascar recorded, 50 are threatened;

Zoos keep 21 Malagasy freshwater fish species: 19 of them endemic & threatened (9 successfully bred in year before survey);

No improvement in ex situ activities since early 2000s;

Most of the threatened species not kept ex situ, including 11 Critically Endangered species;

Integrated in situ & ex situ efforts should be developed/improved.

Glow and Behold: Biofluorescence and New Insights on the Tails of Pitvipers (Viperidae: Crotalinae) and Other Snakes (Paul & Mendyk, 2021).

June 2021

A paper in Herpetological Review looked into tail biofluorescence in pitvipers (Crotalinae) & other snakes:
Crotalinae: 10 genera, 28 species, both captive and wild specimens examined;
Biofluorescence detected in 78.6% of crotaline taxa examined, in both wild & captive individuals;
Fluorescence restricted to tail in various pitvipers: potential association with behaviour or function (possible explanations provided);
Study arose from detection of fluorescence in captive snakes - captive animals contribute to "pure" science and to our understanding of the natural world.

Sentinel behavior in captive meerkats (Huels & Stoeger, 2021).

August 2021

A paper in Zoo Biology studied sentinel behaviour in zoo-housed meerkats:

Some individuals spent more time as sentinels than others ("Super Sentinels" as observed in the wild);

Sentinels reacted more strongly to playback calls of predatory species ability to identify predators not lost in captivity;

Sentinel behaviour = innate but further affected by experience

Localize Animal Sound Events Reliably (LASER): A New Software for Sound Localization in Zoos (Schneider & Dierkes, 2021).

April 2021

A paper in JZBG reported the development and testing of a software for sound localisation in zoos:
Tests included both playbacks and real conditions in a zoo enclosure;
High accuracy in identifying correct position of a sound source;
Software offers opportunities for research and animal welfare monitoring.

The effects of a zoo environment on free‐living, native small mammal species (Elwell et al., 2021).

March 2021

A study in Zoo Biology investigated the presence of native, free-living, small mammal species in different enclosures at Dudley Zoo:

Small mammal species diversity was similar across habitats;

Small mammal abundance was higher in woodland areas;

Lowest abundance near enclosures with predatory species;

Urban zoos can benefit native wildlife by providing green spaces, food sources and shelter.

On‐site genetic analysis for species identification using lab‐on‐a‐chip (Wimbles et al., 2021).

January 2021

A microfluidic device for on-site genetic analysis has been developed and presented in a new paper:

Portable & cost-effective system for DNA & species identification;

Tested on zoo-housed white rhinoceros: quickly identified DNA in dung samples;

Applications to field research & conservation (e.g. population monitoring; quick identification & prosecution of illegal wildlife trade).


Photo credit: Knowsley Safari

Evaluation of an odour detection dog for non-invasive pregnancy diagnosis in polar bears (Ursus maritimus): Considerations for training sniffer dogs for biomedical investigations in wildlife species (Curry et al., 2021)

January 2021

Can odour detection dogs identify pregnancy in faecal samples from zoo-housed polar bears? A study in JZAR found the following:

The dog accurately ignored faecal samples from non-pregnant females during testing (high specificity);

However, the dog only accurately identified faecal samples from pregnant females in the training sessions - it failed during testing (low sensitivity);

Potential reasons discussed: perhaps dog was unable to generalise odour to novel pregnancies?

Flamingo 2020: Journal of the IUCN SSC Flamingo Specialist Group

December 2020

Flamingo 2020 - the open access journal of the IUCN SSC Flamingo Specialist Group

- is now available, featuring 14 papers on both in-situ & ex-situ flamingo-focussed research!


Zoo-based papers:

Paper 5: Enclosure alterations for improved lesser flamingo health and welfare at the Oregon Zoo (Suhn, 2020).

Paper 6: Substrate influence on the prevalence of bumblefoot in captive Chilean flamingos: Assessing the use of infrared thermography as a diagnostic screening tool (Illing et al., 2020).

Paper 7Pink birds and baseball stars… renovations of the flamingo enclosure at the Birmingham Zoo, Alabama, USA (Pitchford, 2020).

Paper 8Hand rearing Chilean flamingo chicks at Belfast Zoo (Murphy, 2020).

Paper 11: Behavioural observations to evaluate natural instinct in hand-raised rescued lesser flamingos in South Africa (Bony, 2020)

Paper 13Cross-fostering as a reproductive strategy for lesser flamingos at the San Diego Zoo Safari Park (Ray, 2020).

Bearing fruit: Piloting a novel judgment bias task in an American black bear (Vonk et al., 2020).

December 2020

A study in Zoo Biology evaluated seasonal changes in optimistic/pessimistic responses in a zoo-housed American black bear, using a novel judgment bias task:

The most optimistic responses observed during mulberry season (when the animal had access to mulberries in outdoor enclosure);

Evidence of quantity-based discrimination;

Potential applications to enrichment programmes.


Photo credit: Detroit Zoo

Paw preference in wolves (Canis lupus): A preliminary study using manipulative tasks (Regaiolli et al., 2020)

December 2020

Do wolves show motor lateralization? A case study investigated paw preference of seven zoo-housed wolves when interacting with enrichment:

✔ Most wolves used one paw rather than both during manipulation;

✔ Lateralization seen in all individuals;

✔ All individuals but the alpha male were right-pawed.


Photo credit: Parco Natura Viva

Coconut feeding of the babirusa (Babyrousa spp.) (Ito et al., 2020)

September 2020

A study published this year looked into coconut feeding behaviour in captive babirusas:

✔ Preference for certain parts of the coconut over others;

✔ They crushed open young coconuts but NOT mature ones;

✔ Parts eaten have no economic value to farmers;

✔ Little evidence suggesting babirusas are pests for farmers.

Calibrating tri-axial accelerometers for remote behavioural observations in Bewick’s swans (Nuijten et al., 2020).

October 2020

Zoo Research can be a great tool in the study of wild individuals! New paper out in JZAR described how the calibration of accelerometer sensors was done in captive Bewick's swans and then subsequently used on free-living animals:
Overall accuracy of 91% across five behavioural classes;
Classification used to generate activity budgets of wild individuals, which showed high accuracy.


Photo credit: Burgers' Zoo

Zoo animals as “proxy species” for threatened sister taxa: Defining a novel form of species surrogacy (Kerr, 2020)

October 2020

New paper in Zoo Biology discusses how the large number of non-threatened species housed in zoos can still play a big role in conservation:
They can be used as "proxy species" for threatened sister taxa that are not common or present in zoo collections;
This can be considered a new form of surrogacy, giving conservation value to zoo animals even when they are not threatened in the wild.


Photo credit: Henry Vilas Zoo

Ex situ options for cetacean conservation (IUCN SSC, 2020)

October 2020

The IUCN Species Survival Commission released the "Ex situ options for cetacean conservation" report, based on a workshop that took place in 2018 at Tiergarten Nürnberg. The report is extensive and detailed, but here are some interesting conclusions:
Several cetacean species suffered swift & drastic declines;
Current gaps in knowledge & information need to be urgently filled, in order to better anticipate & avoid extinctions;
Noticeable improvement in the breeding and care of bottlenose dolphins in captivity - knowledge that is potentially transferable to other species;
Zoo & aquariums have skills & resources that are valuable for integrated conservation actions.

How many bird and mammal extinctions has recent conservation action prevented? (Bolam et al., 2020)

September 2020

New study measured the degree of extinction preventions in bird & mammal species, since 1993:
21-32 bird extinctions prevented;
7-16 mammal extinctions prevented;
Extinction rates would have been 2.9–4.2x higher without conservation;
Zoos among organisations behind these conservation actions


Photo credit: Scimitar-horned oryx reintroduction (ZSL)

Artificial eyespots on cattle reduce predation by large carnivores (Radford et al., 2020)

August 2020

Because we love ALL science, in and outside the zoo, here is a fascinating study on livestock predation... It was found that:
Cattle painted with eyespots are safer from predators (lions & leopards) than both cross-marked & unmarked cattle;
Cross-marked cattle showed higher survival from predators than unmarked cattle;
Artificial marks have the potential to reduce livestock predation.

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