Frej Gammelgård

Mr. Frej Gammelgård

orcid

Research Focus & Metrics

Academic Career Length

3Years (2024-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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30 September 2024 in Animals
Verified
Journal Article
Open access
PDF file
SLSilje Marquardsen Lund
Silje Marquardsen Lund
JNJonas Nielsen
Jonas Nielsen
FGFrej Gammelgård
Frej Gammelgård
MNMaria Gytkjær Nielsen
Maria Gytkjær Nielsen
TJTrine Hammer Jensen
Trine Hammer Jensen
Cino PertoldiCino Pertoldi
Cino Pertoldi
This study investigates the possibility of using machine learning models created in DeepLabCut and Create ML to automate aspects of behavioral coding and aid in behavioral analysis. Two models with different capabilities and complexities were constructed and compared to a manually observed control period. The accuracy of the models was assessed by comparison with manually scoring, before being applied to seven nights of footage of the nocturnal behavior of two African elephants (Loxodonta africana). The resulting data were used to draw conclusions regarding behavioral differences between the two elephants and between individually observed nights, thus proving that such models can aid researchers in behavioral analysis. The models were capable of tracking simple behaviors with high accuracy, but had certain limitations regarding detection of complex behaviors, such as the stereotyped behavior sway, and displayed confusion when deciding between visually similar behaviors. Further expansion of such models may be desired to create a more capable aid with the possibility of automating behavioral coding.

8 June 2024 in Animals
Verified
Journal Article
Open access
PDF file
FGFrej Gammelgård
Frej Gammelgård
JNJonas Nielsen
Jonas Nielsen
ENEmilia J. Nielsen
Emilia J. Nielsen
MHMalthe G. Hansen
Malthe G. Hansen
AAAage Kristian Olsen Alstrup
Aage Kristian Olsen Alstrup
Cino PertoldiCino Pertoldi
Cino Pertoldi
This article applies object detection to CCTV video material to investigate the potential of using machine learning to automate behavior tracking. This study includes video tapings of two captive Bornean orangutans and their behavior. From a 2 min training video containing the selected behaviors, 334 images were extracted and labeled using Rectlabel. The labeled training material was used to construct an object detection model using Create ML. The use of object detection was shown to have potential for automating tracking, especially of locomotion, whilst filtering out false positives. Potential improvements regarding this tool are addressed, and future implementation should take these into consideration. These improvements include using adequately diverse training material and limiting iterations to avoid overfitting the model.

28 August 2024 in Preprints.org
Verified
Preprint
Open access
PDF file
SLSilje Marquardsen Lund
Silje Marquardsen Lund
JNJonas Nielsen
Jonas Nielsen
FGFrej Gammelgård
Frej Gammelgård
MNMaria Gytkjær Nielsen
Maria Gytkjær Nielsen
TJTrine Hammer Jensen
Trine Hammer Jensen
Cino PertoldiCino Pertoldi
Cino Pertoldi
This study investigates the possibility of using machine learning models created in DeepLabCut and Create ML to automate aspects of behavioral coding and aid in behavioral analysis. Two models with different capabilities and complexities were constructed and compared to a manually observed control period. The accuracy of the models was assessed before being applied to 7 nights of footage of the nocturnal behavior of two African elephants (Loxodonta africana). The resulting data was used to draw conclusions regarding behavioral differences between the two elephants and between individually observed nights, thus proving that such models can aid researchers in be-havioral analysis. The models were capable of tracking simple behaviors with high accuracy, but had certain limitations regarding detection of complex behaviors, such as the stereotyped behavior sway, and displayed confusion when deciding between visually similar behaviors. Further expansion of such models may be desired to create a more capable aid with the possibility of automating behavioral coding.

21 October 2025 in Animals
Verified
Journal Article
Open access
PDF file
SLSilje Marquardsen Lund
Silje Marquardsen Lund
FGFrej Gammelgård
Frej Gammelgård
JNJonas Nielsen
Jonas Nielsen
LLLaura Liv Nørgaard Larsen
Laura Liv Nørgaard Larsen
NCNinette Christensen
Ninette Christensen
Cino PertoldiCino Pertoldi
Cino Pertoldi
Animal welfare assessments increasingly aim to quantify enclosure use and activity to support naturalistic behavior and improve Quality of Life (QoL). Traditionally, this is achieved through manual observations, which are time-consuming, subject to observer bias, and limited in temporal resolution due to short observation periods. Here, we compared manual tracking using ZooMonitor with automated pose estimation (SLEAP) in a mother–son pair of black-headed spider monkeys (Ateles fusciceps) at Aalborg Zoo. We collected manual observations on six non-consecutive days (median daily duration: 62 min, mean: 66 min, range: 52–90 min) and visualized this as spatial heatmaps. We applied pose estimation to the same video footage, tracking four body parts to generate corresponding heatmaps. Across most days, the methods showed strong agreement (overlap 83–99%, Pearson’s r = 0.93–1.00), with both highlighting core activity areas on the floor near the central climbing structures and by the door with feeding gutters. Both methods also produced comparable estimates of time spent being active, with no significant difference across days (p = 0.952). Our results demonstrate that computer vision technology can provide a reliable and scalable tool for monitoring enclosure use and activity, enhancing the efficiency and consistency of zoo-based welfare assessments while reducing reliance on labor-intensive manual observations.

26 January 2026 in Animals
Verified
Journal Article
Open access
PDF file
JNJonas Nielsen
Jonas Nielsen
FGFrej Gammelgård
Frej Gammelgård
SLSilje Marquardsen Lund
Silje Marquardsen Lund
APAnja Sofie Banasik Præstekær
Anja Sofie Banasik Præstekær
AFAstrid Vinterberg Frandsen
Astrid Vinterberg Frandsen
Cino PertoldiCino Pertoldi
Cino Pertoldi
The pygmy hippopotamus (Choeropsis liberiensis, Morton, 1849) is classified as Endangered by the International Union for the Conservation of Nature (IUCN). Compared to other large, threatened mammals, this species remains relatively understudied and new findings indicate potential welfare concerns, emphasizing the need for further research on the species welfare in zoological institutions. One approach to improving welfare in captivity is through environmental enrichment. This study investigated the effects of olfactory enrichment on three individual pygmy hippopotamuses through behavioral analysis and heat-map visualization. Using continuous focal sampling, several behaviors were influenced by the stimuli, with results showing a general decrease in inactivity and an increase in environmental engagement and interaction, particularly through scenting behavior. To further enhance behavioral quantification, machine learning techniques were applied to video data, comparing manual and automated behavior classification using the pose estimation program SLEAP. Four behaviors Standing, Locomotion, Feeding/Foraging, and Lying Down were compared. A confusion matrix, time budgets, and Kendall’s Coefficient of Concordance (W) were used to assess agreement between methods. The results showed a strong and moderate agreement between manual and automated annotations, for the female and calf, respectively. This demonstrates the potential of automation to complement behavioral observations in future welfare monitoring.

18 September 2025 in Preprints.org
Verified
Preprint
Open access
PDF file
SLSilje Marquardsen Lund
Silje Marquardsen Lund
FGFrej Gammelgård
Frej Gammelgård
JNJonas Nielsen
Jonas Nielsen
LLLaura Liv Nørgaard Larsen
Laura Liv Nørgaard Larsen
NCNinette Christensen
Ninette Christensen
Cino PertoldiCino Pertoldi
Cino Pertoldi
Animal welfare assessments increasingly aim to quantify enclosure use and activity to support naturalistic behavior and improve Quality of Life (QoL). Traditionally, this is achieved through manual observations, which are time-consuming, subject to observer bias, and limited in temporal resolution due to short observation periods. Here, we compared manual tracking using ZooMonitor with automated pose estimation (SLEAP) in a mother–son pair of black-headed spider monkeys (Ateles fusciceps) at Aalborg Zoo. Manual observations were collected on six non-consecutive days (median daily duration: 62 min, mean: 66 min, range: 52–90 min) and visualized as spatial heatmaps. Pose estimation was applied to the same video footage, tracking four body parts to generate corresponding heatmaps. Across most days, the methods showed strong agreement (overlap 83–99%, Pearson’s r = 0.93–1.00), with both highlighting core activity areas on the floor near the central climbing structures and by the door with feeding gutters. Both methods also produced comparable estimates of time spent active, with no significant difference across days (p = 0.952). These results demonstrate that computer vision technology can provide a reliable and scalable tool for monitoring enclosure use and activity, enhancing the efficiency and consistency of zoo-based welfare assessments while reducing reliance on labor-intensive manual observations.