Andrew D. Walde

Walde Research & Environmental Consulting

Here, we use records between 1998 and 2024 to document the occurrence of a native population of the turtle Kinosternon leucostomum leucostomum (Duméril & Bribon in Duméril & Duméril, 1851) in the Central Depression of Chiapas, Mexico. Morphological measurements are provided to characterize variation among individuals. We report 22 individuals, whic...

Biological communities are structured by a variety of biotic and abiotic relationships, whose understanding forms the basis for effective conservation. Among the myriad factors influencing community dynamics, resource partitioning stands out, potentially enriching ecosystem complexity but also carrying risks for conservation if disregarded. In this...

The global refugee crisis is above all a human tragedy — but it affects wildlife, too

The Critically Endangered Nubian Flapshell Turtle (Cyclanorbis elegans) is found in the White Nile River system in South Sudan and northern Uganda. Over the past few decades , its populations have sharply declined, primarily due to human-induced threats, leading to its near-extinction across almost its entire range. In this paper, we present the re...

We conducted a comprehensive threat analysis of the Swinhoe’s softshell turtle (Rafetus swinhoei), the most endangered freshwater turtle in the world, historically occurring along river systems in Vietnam and China, but currently almost extinct. Here, our goal was to identify the pressures along two main rivers in Vietnam (Black and Red rivers, bot...

The Critically Endangered Nubian Flapshell Turtle (Cyclanorbis elegans) is found in the White Nile River system in South Sudan and northern Uganda. Over the past few decades , its populations have sharply declined, primarily due to human-induced threats, leading to its near-extinction across almost its entire range. In this paper, we present the re...

We conducted a comprehensive threat analysis of the Swinhoe's softshell turtle (Rafetus swinhoei), the most endangered freshwater turtle in the world, historically occurring along river systems in Vietnam and China, but currently almost extinct. Here, our goal was to identify the pressures along two main rivers in Vietnam (Black and Red rivers, bot...

The Critically Endangered Nubian Flapshell Turtle (Cyclanorbis elegans) is found in the White Nile River system in South Sudan and northern Uganda. Over the past few decades , its populations have sharply declined, primarily due to human-induced threats, leading to its near-extinction across almost its entire range. In this paper, we present the re...

Annual induced fires have caused significant changes in the composition and structure of wildlife globally. These events are particularly critical for species with limited mobility and small clutch sizes, such as small and medium-sized freshwater turtles in the tropics. At the same time, this topic has received little attention and has not been doc...

Species inventories and distributional analyses at local resolutions provide essential data on distribution, species richness, diversity, and abundance that can inform resource conservation and management. The country of Belize has 9 native freshwater and terrestrial turtle species including Claudius angustatus (Narrow-Bridged Musk Turtle), Chelyd...

Annual induced fires have caused significant changes in the composition and structure of wildlife globally. These events are particularly critical for species with limited mobility and small clutch sizes, such as certain small and medium-sized freshwater turtles in the tropics. At the same time, this topic has received limited attention and has not...

Pseudemys is a genus of commonly occurring freshwater turtles with limited growth information across their long lifespans. We used 11,361 mark-recapture events to estimate the somatic growth rates of P. nelsoni, P. peninsularis, P. concinna suwanniensis, and P. texana from freshwater springs and developed a Bayesian growth model to estimate the spe...

Historically believed to harbor unrecognized diversity, the taxonomy of the declining genus Macrochelys (alligator snapping turtles) is debated. The original species, M. temminckii, was recently split into M. temminckii, M. apalachicolae, and M. suwanniensis. However, the status of M. apalachicolae is contested. In this study, we generated thousand...

Understanding population demographics of Macrochelys temminckii (Alligator Snapping Turtle) requires long-term studies. Most previous studies do not provide demographic population data. We conducted a mark-recapture study of M. temminckii inhabiting Buffalo Bayou in Harris County, TX, from October 2016 through August 2021. We captured 110 unique in...

Damage to a turtle’s shell can provide evidence of past events such as vehicle collisions, disease, predator encounters, or even a behavioural interaction between members of the same species. Documenting shell damage as part of long-term mark and recapture studies enables researchers to determine population trends, intraspecific interactions and...

Sulawesi Forest Turtles (Leucocephalon yuwonoi) are critically endangered and endemic to the island of Sulawesi. We conducted radiotelemetry and capturemarkrecapture to study their spatial ecology, habitat selection, activity patterns, and demography in FebruaryApril and JuneJuly, 2019. The average area occupied by 14 turtles using the minimum conv...

In 2015, nearly 4000 critically endangered Palawan forest turtles (Siebenrockiella leytensis) were confiscated on their native island of Palawan in the Philippines after being illegally harvested for the international wildlife trade. Local conservation biologists and an international team of veterinary and husbandry personnel evaluated, treated, an...

This report is a ten-year update of the first set of priority recommendations generated from the workshop “Conservation of Asian Tortoises and Freshwater Turtles: Setting Priorities for the Next Ten Years,” co-organised by Mandai Nature and the Wildlife Conservation Society (WCS) at Singapore Zoo over 21–24 February 2011 (Horne et al. 2012). It bui...

The Peninsula Cooter (Pseudemys peninsularis) and the Florida Red-bellied Cooter (P. nelsoni) are considered common throughout much of their respective ranges. Both species occur in numerous habitats in Florida, USA, including rivers, lakes, ponds, freshwater springs, and spring runs. We sampled Peninsula Cooter and Florida Red-bellied Cooter popul...

Context Camera trapping is increasingly used to collect information on wildlife occurrence and behaviour remotely. Not only does the technique provide insights into habitat use by species of interest, it also gathers information on non-target species. Aims We implemented ground-based camera trapping to investigate the behaviours of ground-dwelling...

Movement patterns of turtles can vary depending on natural and anthropogenic pressures and can correlate with sex, size, food availability, reproduction, territorial behaviour, seasonality, location, and habitat. We analysed the movements of Loggerhead Musk Turtles (Sternotherus minor) based on body size, sex, time between captures, and capture seg...

Abstract. Little is known about many life history traits of the Western Alligator Snapping Turtle, Macrochelys temminckii, including the species’ ecology within urban ecosystems. Our study population inhabits waterways of Houston, Texas, the third-largest city in the United States. We conducted a telemetry study on 19.5 km of the Buffalo Bayou that...

Turtles and tortoises (chelonians) have been integral components of global ecosystems for about 220 million years and have played important roles in human culture for at least 400,000 years. The chelonian shell is a remarkable evolutionary adaptation, facilitating success in terrestrial, freshwater and marine ecosystems. Today, more than half of th...

The loggerhead musk turtle (Sternotherus minor) and eastern musk turtle (Sternotherus odoratus) are widespread species considered common throughout much of their respective ranges. Florida populations of S. minor and S. odoratus inhabit a variety of habitats, including freshwater springs and spring runs. We sampled populations of S. minor and S. od...

Comal Springs in New Braunfels, Texas, is the largest freshwater spring west of the Mississippi. The spring is within the Edwards Plateau Savanna Ecoregion of the Southeastern United States Turtle Priority Area. Comal Springs is an environmentally sensitive spring run situated in an urbanized area visited by >1,000,000 people each year and thus may...

We present a review and analysis of the conservation status and International Union for Conservation of Nature (IUCN) threat categories of all 360 currently recognized species of extant and recently extinct turtles and tortoises (Order Testudines). Our analysis is based on the 2018 IUCN Red List status of 251 listed species, augmented by provisiona...

This book presents a brief summary of the 25th most endangered tortoise and turtle species. The summary includes both common and scientific names, distribution, causes of population decrease, and conservation strategies.

Abstract. During a survey of turtles in Weeki Wachee Springs State Park, Florida, USA, in March 2015, 182 turtles representing ten species were captured, marked, and released, including the Florida Softshell Turtle (Apalone ferox), North American Snapping Turtle (Chelydra serpentina), Florida Chicken Turtle (Deirochelys reticularia chrysea), Stripe...

Translocations are a tool widely used by wildlife managers, yet their impact is often insufficiently evaluated. Most translocation studies only assess the initial establishment phase, and the majority of long-term persistence studies to date have only tracked female fecundity. Male genetic integration for mitigative translocations have as of yet no...

Freshwater-turtle ecologists rely on effective baits to capture target species. We conducted a bait-preference study for Sternotherus odoratus (Eastern Musk Turtle) in 2 phases during the 2014, 2015, and 2016 field seasons at Comal Springs, New Braunfels, TX. During Phase 1, we compared the effectiveness of buffalo chicken to other malodourous or p...

There is little information on predator–prey interactions in wind energy landscapes in North America, especially among terrestrial vertebrates. Here, we evaluated how proximity to roads and wind turbines affect mesocarnivore visitation with desert tortoises (Gopherus agassizii) and their burrows in a wind energy landscape. In 2013, we placed motion...

Since 2007 the Turtle Survival Alliance-North American Freshwater Turtle Research Group (NAFTRG) has surveyed aquatic turtles in Volusia Blue Spring State Park, Orange City, Florida, USA. Here, we provide population parameters for the three most common freshwater turtle species, the Peninsula Cooter (Pseudemys peninsularis), Florida Red-bellied Coo...

We present data on large Chelydra serpentina (Snapping Turtle) from 4 freshwater springs in Florida located in Wekiwa Springs, Volusia Blue Spring, Peacock Springs, and Manatee Springs state parks. Several of the turtles captured at Wekiwa Springs and Volusia Blue Springs are larger than the previous Florida record for this species. In the past, Sn...

The Mojave Desert is home to a surprising diversity of flora and fauna that is well adapted to the desert heat and aridity. A keystone species in the Mojave Desert is the Mojave Desert Tortoise (Gopherus agassizii; Cooper, 1863)), which constructs multiple burrows in the sandy and caliche substrate. The burrows provide well-protected refugia with m...

The Ploughshare Tortoise (Astrochelys yniphora; Vaillant, 1885) is the largest extant endemic tortoise on the island of Madagascar. The species is isolated to a small area of mixed palm-savanna, bamboo-scrub, and dry deciduous forest of less than 160 km2 on the northwest coast (Mandimbihasina and Woolaver, 2014). Due to its rarity and attractive go...

In the Mojave Desert of the southwestern United States, adult Agassiz’s desert tortoises Gopherus agassizii typically experience high survival, but population declines associated with anthropogenic impacts led to their listing as a Threatened Species under the US Endangered Species Act in 1990. Predation of adult tortoises is not often considered a...

The Florida softshell turtle, Apalone ferox (Schneider 1783) is considered common and easily visible in many freshwater habitats throughout its range. However, very little population research has been completed on the species due to difficulties associated with capture and long-term marking. We have conducted a mark–recapture study of this species...

Ecosystem engineers play an important ecological role because they modify habitats which are subsequently used by numerous other organisms (Dale and Beyeler, 2001; Wright and Jones, 2004). Burrowing tortoises are considered ecosystem engineers because they construct burrows that are subsequently used by a multitude of heterospecifics (Jackson and M...

The genus Pseudemys represents some of the largest emydid turtles in North America. Surprisingly, many in this genus are poorly studied and despite their large size little is known about their growth. Using mark-recapture data we examined extreme growth in two Pseudemys species, Pseudemys peninsularis and P. nelsoni in a protected spring system in...

Dinosaur reproductive biology is often inferred from the biology of extant taxa; however, taphonomic studies of modern nest sites have focused exclusively on avian, rather than reptilian species. We documented eight Agassiz's desert tortoise (Gopherus agassizii) nests and ten loggerhead sea turtle (Caretta caretta) nests. Gopherus agassizii excavat...

Wildlife managers may consider translocation as a means of conserving a local population, but if augmentation disrupts existing disease dynamics it may initiate an outbreak that would effectively offset any advantages the translocation may have achieved. Contact networks-the pattern of interaction between individuals in a population-can effectively...

Agassiz’s desert tortoise (Gopherus agassizii) is a long-lived species that requires high annual adult survivorship to maintain stable populations. Over the past few decades unsustainable mortality rates have occasionally been reported and are frequently associated with drought or subsidized predators. During the active seasons of 2012 and 2013 we...

Translocation of threatened or vulnerable species is a tool increasingly used for conservation and management. However, in some species, homing and movement behaviors may undermine the success of translocation efforts. For the federally protected Agassiz's desert tortoise (Gopherus agassizii), translocation is a strategy used to manage declining po...

Wildlife managers consider animal translocation a means of increasing the viabil- ity of a local population. However, augmentation may disrupt existing resident disease dynamics and initiate an outbreak that would effectively offset any advan- tages the translocation may have achieved. This paper examines fundamental concepts of disease ecology and...

Characterizing the effects of landscape features on genetic variation is essential for understanding how landscapes shape patterns of gene flow and spatial genetic structure of populations. Most landscape genetics studies have focused on patterns of gene flow at a regional scale. However, the genetic structure of populations at a local scale may be...