Invasive Speices on the Rise?

1st, October, 2020 - University College, London -  Research led by an international team in conjunction with the University College, London discussed how they've predicted there to be a 36% increase in invasive alien species by 2050 in comparison to 2005.

There is significant correlation between the level of a nations GDP and the abundance of invasive species due to improvement in transport, infrastructure etc. It's expected that Europe will see the highest invasion in biological invasions with the predicted arrival of 2,500 species which will be a 64% increase. 

The research team led by the German Senckenberg biodiversity and Climate Research Centre believe it's possible to slow down these rapid introductions with more strict biosecurity measures taking place. 

Invasive species have been an issue in Europe for the past 11 decades, however, enhancement in trapping methods have plateaued where kill traps and mark and recapture methods commonly being deployed. There is a large inventory of invasive species data available for island populations, however, this is not the case for mainland populations. Mainland populations are more complicated due to higher potentials of dispersal and information will be vital. 

The best time to put controls into place is during the early stages before these populations expand and disperse. Constant surveillance using meta genomics would be a useful tool where it will help detect early introduction where the intensity of invasion is low and will help understand pathway patterns. 

This study has used a model with great variations between different regions where the largest increase predicted to be in Europe due to their connectivity to many other continent, high GDP, poor border control, strong political relationships with other high GDP nations etc. Australia have been estimated to seeing the lowest increase due to strong border controls and their dis connectivity from other nations. 

 

References

Tim M Blackburn, Céline Bellard and Anthony Ricciardi. Alien versus native species as drivers of recent extinctions. Frontiers in Ecology and the Environment, 2019 DOI: 10.1002/fee.2020

University College London. "Alien species to increase by 36% worldwide by 2050." ScienceDaily. ScienceDaily, 1 October 2020. <www.sciencedaily.com/releases/2020/10/201001090143.htm>.

Bye Bye Birdie

It has been warned that many endangered bird species is predicted to decline by 50% in species by the turn of the century. This primary factors responsible for this decline is the rapid decline is due to the transition from agricultural fields to a more profitable, homogeneous crop cultivation in wine vinyards and olive. 

Low intensive agriculture practices across European lands had created a semi-natural aggro steppes ideal for maintaining populations of these endangered bird species such as great bustards, lesser kestrel rollers etc. 

These aggro steepes had become special areas of conservation in the early 2000's under the EU natura 2000. Researchers for the University of East Anglia (UEA) and the University of Lisbon investigated the effectiveness of these protected areas of the risk of great bustards population in the Iberian peninsula.  

It had been discovered that traditional, less intensive vineyards and olive groves were suitable at maintaining great bustard populations, however, with demands increasing these areas have become more heavily cultivated with permanent crops. If these market pressures are maintained it is estimated that the predicted 50% of endangered species will have gone extinct. Researchers have stated that lack of enforcement and initiatives have led to the demise to the EU Natura 2020 network. 

The co-supervisor of this survey, Dr Aldina Frances of UEA had stressed of the importance of development of new agricultural practices and improving the productivity such as improving efficiency  of photosynthesis of crops which will be looked in another post. The improvement in efficiency will alleviate the pressures and help prevent high intensive farms. 

Great bustard breeding sites are often chosen based on where the mother had been laid and so it is common for many generations of these great bustards to be at the same site and so the transition from aggro steppes to vinyards/ groves. 

It was declared that allocating large intensive aggro areas to less intensive management would greatly improve the endangered bird populations where they deliver a variety of ecosystem services and resilience. Leaving large unkept margins which will encourage larger invertebrate composition and diversity where chicks feed exclusively on invertebrates for numerous invertebrates. The survival of these chicks are significantly dependent on their food availability near their nesting site. Improving invertebrate composition within the area will create a larger bottom heavy age structure which is the main way ecologists predict population growth. 

A serious concern over these protected sites is that it will create small isolated islands only allowing a carrying capacity for small populations. This will reduce the genetic diversity where the genetic alleles have little diversity between individuals in each island population. Inbreeding will then make it difficult for these individuals to adapt to environmental change and offspring will have reduced chances of survival. Analysis of the genetic diversity of these individuals will be vital and once alleles become too similar within the population, translocation of individuals from a different protected area (island) will have to be introduced for genetic rescue. 

 

Chimpanzee

Our closest cousin, the chimpanzee (Pan troglodytes) is currently classed as endangered under the IUCN with it estimated to consist of a population of between 172,700 to 299,700 chimpanzees remaining. Chimpanzees have already gone domestically extinct in 4 countries already and are put under serious pressure in all other countries they reside in. 

This population has displayed an exponential decline with a report coming from the American Journal of Primatology (2017) which had predicted there to be an 80.2% decline within the last 25 years. More recent studies have said that great apes are in less danger than previously thought. Although, chimpanzees are in a better position, they are still seriously vulnerable and this will provide us with greater opportunity to prevent the extinction of this species. The largest  survey of great apes had inferred there to have been a fifth decrease in chimpanzees between 2005-2013.

Great apes are seriously vulnerable to decrease in population as they are classed as a type I in the survivorship curve which means they have very few natural predators and so will have a slow reproductive rate and prolonged maternal care. These species are highly vulnerable to this decline as they aren't capable of replenishing their population. 

This reduced population of chimpanzees are a by-product of habitat loss, degradation, commercialization of bushmeat and being infected by various fatal diseases such as ebola. Logging is a serious factor for this decline.

Morgan and Sanz (2007) had stated logging causes the loss of their food source, habitat and creates disruptions. This is especially evident in clear cutting logging. 

Studies on selective logging has been undertaken on the effects it creates on the great apes. It was discovered that most gorillas displayed positive responses to selective logging, however, the chimpanzee were significant more vulnerable. Positive effects are a result from increased light that can reach the forest floor and there is a strong correlation between the amount of sunlight the forest floor receives and the abundance/ diversity of the floral composition providing a greater food source prior to the logging. Although, chimpanzees more commonly responded negatively to all logging events there was rare occasions they displayed positive responses.

It is hypothesized that this decline response is because of the chimpanzee's territorial behaviour to one another. When logging begins, the chimpanzees will feel unsafe in their territory they will migrate which is likely to force them to enter a different clan's  territory. This will then lead to brutal fighting between the chimpanzee's clans.

References
Gaworecki, M., 2017. Western Chimpanzee Numbers Declined By More Than 80 Percent Over The Past Quarter Century. [online] Mongabay Environmental News. Available at: <https://news.mongabay.com/2017/07/western-chimpanzee-numbers-declined-by-more-than-80-percent-over-the-past-quarter-century/> [Accessed 22 July 2020].

  World Wildlife Fund. 2020. Chimpanzees | Species | WWF. [online] Available at: <https://www.worldwildlife.org/species/chimpanzee> [Accessed 22 July 2020].

World Wildlife Fund. 2020. Largest Ever Study Of Gorillas And Chimpanzees Finds More Than Expected | Stories | WWF. [online] Available at: <https://www.worldwildlife.org/stories/largest-ever-study-of-gorillas-and-chimpanzees-finds-more-than-expected> [Accessed 22 July 2020].

Aardvark daytime activities detrimental to species

Researchers of the University of the Witwatersrand (UW) have examined the reasons for why aardvarks are now active during the day and how this may be detrimental to the population. This daytime wandering is becoming a regular occurrence in dry southern African countries. 

UW had worked in conjunction with the University of Cape Town and the University of Petoria to better understand what the change from nighttime to daytime active periods means for the species. Studies were performed on the aardvark population in Tswalu where body temperatures and activity periods were monitored across a 3 year period. Dr Nora Weyer completed her PhD research on this nocturnal animal using satellites in conjunction with the monitoring of this population's body temperature and activity period. 

After this study, it was confirmed that the hypothesis formed prior to the survey had been accepted. It was confirmed that the drought's that have recently become more frequent are the reason for this shift. Drought's are responsible for the death of many vegetation within this arid region which then remove a major food source for the aardvark (ant & termites). The aardvark changed their active periods from night to day so they can better conserve their energy by not having to increase their body temperature in the colder nights especially during drought periods where they don't obtain a sufficient energy source.

During the study 5 out of 6 aardvarks being monitored had died because of these unhospitable conditions. The aardvark acts as an ecosystem engineer as they provide shelter for many organisms incapable of burrowing which will create detrimental effect onto this vulnerable, unique ecosystem.

Aardvarks have been able to cope in the past with these harsh arid conditions, however, based on previous studies it is predicted that these droughts will be too much for these populations to handle.

• Yirka, B., 2017. Study Suggests Climate Change May Kill Off The Aardvark In Some Areas. [online] Phys.org. Available at: <https://phys.org/news/2017-07-climate-aardvark-areas.html> [Accessed 20 July 2020].
• ScienceDaily. 2020. Daytime Aardvark Sightings Are A Sign Of Troubled Times: Wits Researchers Find That Aardvarks Feeding In The Daytime During Droughts Might Be Starving. [online] Available at: <https://www.sciencedaily.com/releases/2020/07/200709092459.htm> [Accessed 20 July 2020].

Are cukoo's the new dodo bird?

The Bristosh cuckoo population has displayed a 71% decline within the previous 25 years. This decline has been a mystery to many until monitoring was recently taken place. Tracking devices were attached to 42 male cuckoo birds prior to their migration. This survey had discovered that these birds have 2 migratory routes. One route goes from Britain to the African continent via Spain and another where they bypass Italy. Those who flew threw Italy ( a longer route) had a significantly lower mortality rate upon their return to Britain/ Ireland. It was noted that the majority of deaths had occurred prior to reaching the continent of Africa and so it is hypothesized the decline is primarily yet another result of climate change. 

Spain have suffered from severe droughts and fires meaning there will be less water source. More time had been spent in breeding sites for those bypassing Italy with it being expected to be because they're developing a greater deal of pre migratory fattening. Due to this lack of precipitation there is also a decrease in vegetation growth that makes up most of the caterpillar/ moth's diet. This is significant as the caterpillar and moths are the major food source for the cuckoo bird. This lack of food source and water availability will then quite obviously cause death especially during a harsh migratory route. 

Spring migration is commonly associated with energy selected migration and Spring migration is related to time selected migration. There are currently issues on the timing of Spring migration due to the incompatible breeding resources available where the hosts nests are located where the cuckoo wishes to lay leading to an exploitative interaction.

https://en.wikipedia.org/wiki/File:Cacomantis_flabelliformis.jpg

References

•  Briggs, H., 2016. Cuckoo Decline Finally Mapped. [online] BBC News. Available at: <https://www.bbc.com/news/av/science-environment-36837641/cuckoo-decline-finally-mapped> [Accessed 11 July 2020].
•  Hewson, C., Thorup, K., Pearce-Higgins, J. and Atkinson, P., 2016. Population decline is linked to migration route in the Common Cuckoo. Nature Communications, 7(1).

Macaws in Decline

Macaw parrots are the largest parrots and are native to central and south America. These parrots found in the rainforests live in the canopy layer where they nest in the holes formed into the palm trees. Macaws fly inbetween these trees and the fruit they feed on such as arguaje palm fruit and has close association to urban areas near miami due to the high availability of bird feeders and for this reason it's unlikely they'll become an invasive species to the native wild species outside of the macaws natural range. All 18 macaw species are currently in decline with 8 of these species endangered and 2 thought to be extinct in the wild. Their greatest downfall in contributing to their vulnerability is their loud noises emitted for communication, vibrant colours, their lack of fear of humans and their predictability making them vulnerable to poaching.

There is serious reason for concern for the Florida population of macaw species. The decline is responsible due to their spectacular vibrantly coloured coat and their sociability which has created a huge demand for these species  in the pet trade. There is such a high demand that the value of each may cost upwards of $10,000. Although there are laws in Florida inhibiting the capture, trade or possession of birds native to Florida (Federal Migratory Bird Treaty Act), Macaws are not considered native and so this piece of legislation does not aid in the protection of the macaw assemblage. Poaching is widely advertised reaching optimum audience size and with little known by even zoologists, poachers have little information on optimum conditions for the survival of these macaw speices which has led to detrimental effects onto the population. Poachers captures the young individuals to optimize the fecundity of the breeding pairs and turn as much of a profit as possible. It was recorded that there was a mortality rate of 99% of those young upon being captured and being sold. The age structure has direct effects on growth of the population and using life tables is used in determining population growth in animal population. These life tables tabulate the number of individuals in each age class as each class is associated with different birth and death rates. This capturing of these young macaws results in a decrease in the predicted growth. This practice is detrimental as they have low reproductive rates where each individual may not reproduce every year even with optimal conditions. This poaching process of offspring is not capable of sufficiently replenishing their population and the removal of the young decreases the fecundity of the population. Although, in depth surveys have not been performed on the Miami Macaw population it is widely believed that this population belongs to a single flock and so all individuals in this population have similar genetic make ups due to restricted viable mates. Translocation of suitable macaw individuals should be immigrated into these habitats so they can achieve genetic rescue. Genetic rescue aims to diversify the gene pool and to increase the offspring fitness for survival.

Despite not causing negative implications onto the surrounding native species, fears of disturbance by agriculturists have also caused a decline in populations near settlements. The agriculturists would kill the macaws as they feared they'd disturb their livestock with their loud noises and damage the palm trees that they nest in.

Populations residing in the Amazon rain forest  are in decline because of the defforestation. Based on satellite images taken of the rainforest in 2018, 7,900km has been erradicated between August 2017 and July 2018 (11 months) so they convert the rainforest into a more profitable practice (meat production). The deforrestation quite obviously destroys a whole flocks nesting sites and food sources (insect and fruit). Brightsmith who had been underwritten by the Schubot , Earthwatch Institutes and Rainforrest expeditions and was a researcher Texas A&M University had discussed an overlooked factor for this assemblages decline was responsible from the demand for Arguaje palm fruit which had served as the prefferable nesting site and food source of these parrots. He also added that we 'need to learn more about their breeding habitats, their migration routes and many other thing' if we wish to replenish this population.