Pandas in zoos still aren’t mating enough – and jet lag could be to blame
Panda bears may be suffering from ‘jet lag’ when kept in zoos – potentially lowering their already sluggish libido, suggests a new study.
Giant pandas living in captivity outside the latitude of their normal range are less active, say scientists, potentially affecting their welfare.
They explained that all animals have an internal clock – called a circadian clock – which is regulated by cues from their environment.
But animals in zoos can be exposed to very different cues compared to animals in the wild.
Since all animals’ circadian clocks are linked to their behaviour and physiology, scientists say it could be ‘significant’ to their welfare – which is crucial to maintaining captive populations of species at high risk of extinction, such as giant pandas.
Researchers set out to understand how the ‘jet lag’ of living in latitudes they did not evolve in, and therefore getting cues for their circadian clocks which they are not adapted to, affects pandas.
‘Animals, including humans, have evolved rhythms to synchronise their internal environment with the external environment,’ said lead author Kristine Gandia, of the University of Stirling.
‘When internal clocks are not synchronised with external cues like light and temperature, animals experience adverse effects.
‘In humans, this can range from jet lag to metabolic issues and seasonal affective disorder.’
She said since giant pandas live highly seasonal lives, they are an ideal study species for understanding how the circadian clock affects well-being and behaviour.
The researchers said pandas prefer to eat certain species of bamboo and love new shoots, which triggers a migration as the shoots emerge in spring.
The migratory season is also the breeding season, likely because finding mates is easier when they are all following the same nutritious shoots.
In addition, pandas are so popular that many zoos that house them maintain public webcams, so behaviour can be monitored 24 hours a day.
Zoos also provide a chance to understand why the circadian clock matters for animal well-being, by moving species to latitudes outside their normal range where important cues such as daylight and temperature ranges will be different.
The researchers say the changed conditions could potentially leave animals ‘jet lagged’ – especially if their circadian rhythms are very dependent on seasonality, like pandas.
They also believe animals in captivity could also be affected by anthropogenic cues, such as keepers’ regular visits.
Ms Gandia, a PhD student, and her colleagues used webcams to monitor 11 giant pandas at six zoos both inside and outside pandas’ natural latitudinal range.
Every month for a year, they conducted a day’s worth of hourly focal sampling to gauge how pandas’ behaviour changed through a day, and how that changed across a year.
The team noted general activity, sexual behaviour, and abnormal behaviour.
Their findings, published in the journal Frontiers in Psychology, showed that daylight and temperature were particularly important cues for pandas, closely associated with general activity in latitudes that matched their natural range in China.
Captive pandas showed three peaks of activity over 24 hours, including one at night, just like their wild counterparts. Adult pandas only displayed sexual behaviors in the daytime, which could make it easier to find mates in the wild.
Pandas outside their home latitude were less active, perhaps because daylight and temperature cues differed at different latitudes.
The research team found that the behaviour of the pandas in mismatched latitudes differed from those in matched latitudes most when the pandas in mismatched latitudes were receiving more divergent daylight and temperature cues.
‘When giant pandas are housed at higher latitudes – meaning they experience more extreme seasons than they evolved with – this changes their levels of general activity and abnormal behaviour,’ said Ms Gandia.
The research team also found that all study pandas reacted to zoo-specific cues, becoming very active in the early morning and showing abnormal behaviours that could represent anticipation of keepers visiting with fresh food.
The researchers also noted the pandas’ abnormal and sexual behaviour fluctuated at similar points.
The team believe it could represent ‘frustration’ that they can’t migrate or mate as normal.
Pandas who lived at mismatched latitudes performed fewer abnormal behaviours, possibly because they weren’t getting the same cues for sexual behaviours.
‘To expand on this research, we would want to incorporate cycles of physiological indicators,’ said Ms Gandia.
‘Importantly, we would want to assess sexual hormones to understand the effects the environment may have on the timing of release.’
She added: ‘This could help us further understand how to promote successful reproduction for a vulnerable species which is notoriously difficult to breed.’
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