Bright artificial light at night is associated with increased body mass, poor reproductive success and compromised disease tolerance in Australian budgerigars (Melopsittacus undulatus)

Abstract

Artificial light at night (ALAN) can cause circadian disruption and result in adverse behavioral and ecological effects in free‐living birds, but studies on captive pet birds as companion animals have been infrequent. We studied the effects of exposure to bright ALAN on body mass, melatonin sulfate levels, reproduction and disease severity in Australian budgerigars (Melopsittacus undulatus) kept in captivity. During the experiment, birds were kept under outdoor temperature, humidity and natural photoperiod from September to December. A total of 48 birds were equally split into 4 groups (6 mating pairs each) and concurrently exposed to ALAN of 200 lux with different duration (0, 30, 60 and 90 min). Monthly observations were recorded for all dependent parameters. ALAN exposure increased mass gain and suppressed melatonin levels in a dose‐dependent manner, especially during December. In addition, ALAN exposure in all duration groups decreased egg production and reduced hatchability from 61% ± 14% in the ALAN‐unexposed control group to 0% in the ALAN‐exposed birds. Disease severity was also found to increase in line with the duration of ALAN exposure. In captive M. undulatus, ALAN exposure was demonstrated to affect photoperiodic regulation with subsequent excess mass gain and reproduction impairment, and increased susceptibility to infections plausibly through duration dose‐dependent suppression of melatonin. To the best of our knowledge, this is the first study to demonstrate a possible association between acute bright ALAN of increasing duration and both natural development of infections as well as reproductive cessation in captive birds. Our findings could be used to improve breeding conditions of captive birds.

Long-term exposure to artificial light at night in the wild decreases survival and growth of a coral reef fish

“…It is therefore unsurprising that there is little consensus as to ALAN's effects on an organism's survival and growth. The studies comparing continuous exposure to light have produced conflicting results, ranging from increased growth [ 22 , 23 ], no difference in growth [ 24 ], variation in growth responses across species [ 25 ], and decreased growth [ 26 , 27 ]. Furthermore, exposure to ALAN has been shown to increase animal mortality in some species [ 13 , 28 ], but not in others [ 15 ].…”

Seasonal associations with light pollution trends for nocturnally migrating bird populations

“…At the individual level, ALAN can disrupt biological rhythm, behavior, and physiology for both migratory and resident species. Examples include adverse effects on body mass and reproductive success (Malek & Haim, 2019), disease tolerance (Kernbach et al, 2021; Malek & Haim, 2019), immunity and parasitism (Becker et al, 2020), intestinal microbiota (Jiang et al, 2020), breeding phenology (Dominoni et al, 2020; Kempenaers et al, 2010), migration phenology (Smith et al, 2021), foraging activity (Amichai & Kronfeld‐Schor, 2019), and sleeping behavior (Aulsebrook et al, 2020; Sun et al, 2017).…”

Comparison of Some Behavioural Responses in Budgerigars (Melopsittacus undulatus) Raised in Cages Enriched with Coloured LED Lights

“…The study was conducted in a controlled setting with a temperature of 25 ± 2 °C, a relative humidity of 55 ± 5%, and a noise level of 35–40 dB. A total of four commercial cages made of easy-to-clean metal, measuring 60 × 40 × 30 cm, one for each group, were utilized in the study [ 30 , 47 , 48 ]. The study was carried out with three birds in each of the four groups, organized homogeneously after the quarantine period had expired (at the end of the 15 days).…”

“…Birds that are bred as pets may be exposed to the possible negative effects of light more than wild birds [ 30 ]. The species of M. undulatus is one of the best examples of this condition.…”

“…The primary issue is that the bird spends the time that it would normally spend in the dark in its natural environment in the light, depending on human activities. Anomalies including stress, obesity, and behavioural disorders develop in birds due to this condition [ 30 , 31 ].…”