Browsing SDZWA Research Publications by Subject "LIGHT"
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Characterization of progressive keratitis in Otariids: Otariid keratitis... ‘Otariid Keratitis’ occurs in all populations of eared seals evaluated. A large‐scale epidemiological study is ongoing to identify the risk factors that contribute to this disease. Exposure to chronic sunlight appears to be an important risk factor as shade diminishes clinical signs; animals kept out of sunlight the majority of the time have less severe clinical signs....
Metabolic bone disease in juvenile koalas (phascolartcos cinereus)Due to climate restrictions in parts of North America and Europe, koalas (Phascolarctos cinereus) are housed indoors. Koala young (joeys) raised indoors are susceptible to the development of metabolic bone disease (MBD) due to a lack of exposure to natural ultraviolet light to themselves and their female paren....
Provision of ultraviolet basking lights to indoor housed tropical birds and their effect on suspected vitamin D3 deficiencyVitamin D deficiency (measured as 25(OH)D3) can occur if birds are fed a vitamin D deficient diet and do not have access to ultraviolet B light (UVB). This can result in eggs with deficient yolks and consequent metabolic bone disease (MBD) in chicks. In this study, hypovitaminosis D was suspected in 31 adult birds, from five orders, housed indoors long-term without prior access to UVB light. The study aimed to assess the effect of providing UVB basking lights on their vitamin D status and incidence of MBD in chicks. It also aimed to assess whether the birds would access the UVB provided. Breeding and pathology records were analysed, and birds were blood tested for 25(OH)D3 before, and 12 months after, being provided with access to UVB basking lights. The area of perching with UVB irradiance was filmed before and after the UVB basking lights were switched on. There was a significant increase in 25(OH)D3 after 12 months of UVB provision from a mean of 9.3 nmol/L to 14.2 nmol/L (p = 0.001, CI = 2.35 to 9.47). Annual incidence of metabolic bone disease in chicks dropped from an average of 14.4% over the three years prior to UVB provision to 2.8% in the two years afterwards, although this reduction was not statistically significant. Birds appeared to actively seek the basking spots and significantly increased the proportion of time spent in the area of UVB irradiance (p = 0.02). No correlation was found between the total amount, or change in time spent in the UVB area and the final, or change in individual birds circulating 25(OH)D3 levels. These results show that indoor housed birds will bask in UVB light if provided and this radiation can increase vitamin D levels of the birds, which may prevent MBD in their offspring.
Size-related differences in the thermoregulatory habits of free-ranging Komodo dragons.Thermoregulatory processes were compared among three-size groups of free-ranging Komodo dragons (Varanus komodoensis) comprising small (5–20 kg), medium (20–40 gm) and large (40–70 kg) lizards. While all size groups maintained a similar preferred body temperature of 35, they achieved this end point differently. Small dragons appeared to engage in sun shuttling behavior more vigorously than large dragons as represented by their greater frequency of daily ambient temperature and light intensity changes as well as a greater activity and overall exposure to the sun. Large dragons were more sedentary and sun shuttled less. Further, they appear to rely to a greater extent on microhabitat selection and employed mouth gaping evaporative cooling to maintain their preferred operational temperature and prevent overheating. A potential ecological consequence of size-specific thermoregulatory habits for dragons is separation of foraging areas. In part, differences in thermoregulation could contribute to inducing shifts in predatory strategies from active foraging in small dragons to more sedentary sit-and-wait ambush predators in adults.