Andrea F. Currylow

Burmese pythons (Python molurus bivittatus) and African rock pythons (Python sebae) have established invasive populations in southern Florida, severely disrupting local ecosystems. We analysed necropsy data from 2,179 pythons captured between 2006 and 2022, revealing nine cases of coelomic foreign bodies, primarily consisting of bird beaks, which presumably entered the coelom following gastrointestinal perforations during prey consumption. Despite the presence of foreign bodies, most examined pythons exhibited no obvious health issues. These findings indicate that the consumption of prey with sharp morphological features, such as wading birds, may not impede the pythons’ survival or health significantly, thereby underscoring their adaptability as apex predators in the Greater Everglades Ecosystem.

¬¬The carbon and nitrogen stable isotope composition of animal tissues provide valuable insights into foraging ecology and trophic interactions. However, dietary isotopic composition varies widely among organisms and tissues. This study established carbon and nitrogen trophic discrimination and tissue-to-tissue conversion factors in Burmese pythons (Python molurus bivittatus) and explored tissue turnover dynamics. Trophic discrimination conversion factors (Δ ¹³ C _diet-tissue and Δ ¹⁵ N _diet-tissue ) were established by analyzing shed skin from captive pythons and comparing to known diet values. Tissue-to-tissue conversion factors between muscle, dermis, and scale and muscle and shed were determined from paired tissue samples from the remains of stored snake tail clips. Tissue turnover time was investigated with opportunistically collected samples: red blood cells from wild snakes held in captivity on a known diet. The Δ ¹³ C _diet-tissue and Δ ¹⁵ N _diet-tissue values between diet and shed were significantly different between adult and subadult snakes. For Δ ¹³ C _diet-tissue , adult shed averaged 0.8‰ higher than diet while subadult shed averaged -1.4‰ lower than diet. Both age groups had higher mean δ ¹⁵ N values than their diet, resulting in positive Δ ¹⁵ N _diet-tissue values (subadults = 2.3 ± 0.4 ‰, adults = 4.3 ± 0.2 ‰). Conversion equations were established between muscle, dermis, scale, and shed skin. Tissue turnover time could not be determined over the duration of available samples. Our results highlight the importance of taking ontogeny into consideration when interpreting Burmese python stable isotope composition. The isotopic metrics measured here can be used in future ecological research on Burmese pythons and expand the limited information on isotopic dynamics of herpetofauna.

RATIONALE The carbon and nitrogen stable isotope composition of animal tissues provide valuable insights into foraging ecology and trophic interactions. However, dietary isotopic composition varies widely among organisms and tissues. This study established carbon and nitrogen trophic discrimination and tissue-to-tissue conversion factors in Burmese pythons ( Python molurus bivittatus ) and explored tissue turnover dynamics. METHODS Trophic discrimination conversion factors ( Δ ¹³ C _diet-tissue and Δ ¹⁵ N _diet-tissue ) were established by analyzing shed skin from captive pythons and comparing to known diet values. Tissue-to-tissue conversion factors between muscle, dermis, and scale (n=25) and muscle and shed (n=10) were determined from paired tissue samples from the remains of stored snake tail clips. Tissue turnover time was investigated with opportunistically collected samples: red blood cells from wild snakes held in captivity on a known diet. RESULTS The Δ ¹³ C _diet-tissue and Δ ¹⁵ N _diet-tissue values between diet and shed were significantly different between adult and subadult snakes. For Δ ¹³ C _diet-tissue , adult shed averaged 0.8‰ higher than diet while subadult shed averaged -1.4‰ lower than diet. Both age groups had higher mean δ ¹⁵ N values than their diet, resulting in positive Δ ¹⁵ N _diet-tissue values (subadults = 2.3 ± 0.4 ‰, adults = 4.3 ± 0.2 ‰). Conversion equations were established between muscle, dermis, scale, and shed skin. Tissue turnover time could not be determined over the duration of available samples. CONCLUSIONS Our results highlight the importance of taking ontogeny into consideration when interpreting Burmese python stable isotope composition. The isotopic metrics measured here can be used in future ecological research on Burmese pythons and expand the limited information on isotopic dynamics of herpetofauna.

Invasive Burmese pythons (Python bivittatus) are extremely cryptic animals. Although their conservation status in their native range is Vulnerable, in the Greater Everglades Ecosystem (Florida, USA) they have become a dominant destructive force and usually are immediately removed whenever found. This poses a paradox where removals are occurring, yet the study and understanding of python ecology is needed to inform removal methods. An important component of life history includes the nesting season, but little is known about python nest site selection, nest brooding, thermogenesis, or hatching success in the wild. Here, we present the first complete and most detailed report of oviposition and brooding for this biologically significant time period of a female Burmese python. We describe anthropogenic nest site selection, document the extent of shivering thermogenesis, describe brooding behaviors, and provide photo‐documentation of complete hatching of the largest python clutch on record.

N ative to southeastern Asia, the Burmese Python (Python bivittatus Kuhl 1820) is an invasive species established in southern Florida (Snow et al. 2007; Krysko et al. 2016; Krysko et al. 2019). Pythons are documented as having negative effects on the Greater Everglades Ecosystem and they have proven to be a complex problem for managers trying to control populations (Guzy et al. 2023). This species can move long distances (

Burmese pythons (Python molurus bivittatus) are native to southeastern Asia, however, there is an established invasive population inhabiting much of southern Florida throughout the Greater Everglades Ecosystem. Pythons have severely impacted native species and ecosystems in Florida and represent one of the most intractable invasive-species management issues across the globe. The difficulty stems from a unique combination of inaccessible habitat and the cryptic and resilient nature of pythons that thrive in the subtropical environment of southern Florida, rendering them extremely challenging to detect. Here we provide a comprehensive review and synthesis of the science relevant to managing invasive Burmese pythons. We describe existing control tools and review challenges to productive research, identifying key knowledge gaps that would improve future research and decision making for python control.

The design of successful invasive species control programs is often hindered by the absence of basic demographic data on the targeted population. Establishment of invasive Burmese pythons (Python molurus bivittatus) in the Greater Everglades Ecosystem, Florida USA has led to local precipitous declines (> 90%) of mesomammal populations and is also a major threat to native populations of reptiles and birds. Efforts to control this species are ongoing but are hampered by the lack of access to and information on the expected biological patterns of pythons in southern Florida. We present data from more than 4,000 wild Burmese pythons that were removed in southern Florida over 26 years (1995–2021), the most robust dataset representing this invasive population to date. We used these data to characterize Burmese python size distribution, size at maturity, clutch size, and seasonal demographic and reproductive trends. We broadened the previously described size ranges by sex and, based on our newly defined size-stage classes, showed that males are smaller than females at sexual maturity, confirmed a positive correlation between maternal body size and potential clutch size, and developed predictive equations to facilitate demographic predictions. We also refined the annual breeding season (approx.100 days December into March), oviposition timing (May), and hatchling emergence and dispersal period (July through October) using correlations of capture morphometrics with observations of seasonal gonadal recrudescence (resurgence) and regression. Determination of reproductive output and timing can inform population models and help managers arrest population growth by targeting key aspects of python life history. These results define characteristics of the species in Florida and provide an enhanced understanding of the ecology and reproductive biology of Burmese pythons in their invasive Everglades range.