Tag: Deforestation

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Urban parakeet by Dr Matt Geary

Urban parakeet
Feeds in small parks and gardens
Missing from forests

By Matt Geary

As with many islands around the world, the island of Hispaniola in the Caribbean is home to a number of bird species found only there. Hispaniola is divided between two countries, Haiti and the Dominican Republic. Both countries have experienced severe environmental change since European colonisation, including considerable forest loss and agricultural expansion. Hispaniolan parakeet (Psittacara chloropterus) is hard to find across the Dominican Republic but a considerable population lives in the capital city, Santo Domingo. Our work explores how these vulnerable island endemics use the urban environment.

In 2019, our research team spent three months walking through parts of the city where parakeets are found, counting birds as well as measuring the natural environment around them. They covered 60 1 km2 squares of Santo Domingo, visiting each square three times. As well as looking for parakeets, they recorded sightings of another endemic, Hispaniolan woodpecker, a species which makes cavities in trees where parakeets are potentially able to nest. The team were also on the lookout for parakeet nest sites in trees and buildings.

Hispaniolan parakeet (Psittacara chloropterus). Image credit: Martingloor.

The population in the city is certainly large. We counted around 1500 birds at a communal roost site in the city centre and saw lots of birds on our surveys. We found that parakeet distribution within the city was related to the number of different tree species within the square and saw more parakeet groups where there were more small greenspace patches. This suggests Hispaniolan parakeets are using street level green spaces like small parks and gardens for foraging rather than relying on large areas of vegetation. We only found three locations where parakeets were nesting, all of which were previously know – one palm tree and two communal roosts in buildings.

This species certainly needs some support across the island of Hispaniola and we hope that by improving our knowledge about this population, which may be the largest remaining, we can help to improve the outlook for the species as a whole. Our work continues on this species and other Hispaniolan endemics. @AndreaThomen is putting the miles in with survey work across the island for her PhD research so we hope to have much more to report in the near future.

Further reading: Geary, M., Brailsford, C.J., Hough, L.I., Baker, F., Guerrero, S., Leon, Y.M., Collar, N.J. and Marsden, S.J., 2021. Street-level green spaces support a key urban population of the threatened Hispaniolan parakeet Psittacara chloropterus. Urban Ecosystems, pp.1-8. https://link.springer.com/article/10.1007/s11252-021-01119-1

Dr Matt Geary (https://mattgeary.github.io/) is a Conservation Ecologist working in the Conservation Biology Research Group at the University of Chester. Twitter: @MattGeary

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Holdfast

Marine forests sway,
sheltering, pristine, unchanged.
For how much longer?

Giant kelp forests are some of the most diverse, productive and dynamic ecosystems on the planet. A marine algae (not a plant), giant kelp anchors itself to the seabed and grows up towards the surface, with some species growing up to 30-60 centimetres vertically a day to reach heights of 45 meters. Whilst typically found in temperate and polar coastal oceans, deep water kelp forests have been discovered in clear tropical waters where the sunlight can penetrate far enough below the water surface for the kelp to grow, potentially as far down as 200 meters.

Kelp forests are home to a vast number of species, from those living in the surface canopy to those on the seafloor. This makes them key areas to protect for species richness, much like rainforests and coral reefs. Yet many kelp forests are under threat due to marine pollution, water quality, kelp harvesting, overfishing, invasive species and climate change.

This makes the recent survey of kelp forests in southern South America heartening. Friedlander et al. (2020) re-surveyed 11 locations at the easternmost extent of Tierra del Fuego and compared their findings to surveys originally conducted in 1973. They found no differences in kelp densities or anchor diameter. Sea urchins, if not kept in check, can decimate kelp forests but the researchers also found no difference in sea urchin numbers. Additionally, comparisons of satellite imagery showed no long-term trends over the past 20 years.

It’s thought that the remoteness of the location has meant these kelp forests have been relatively unaffected by human disturbance, although increases in sea temperature as a result of climate change are likely to have an impact in the future.

A note about ‘Holdfast’ – The title refers to both the wish that kelp forests such as the one surveyed in this study persist and survive, and to the root-like mass that anchors kelp to the seafloor which is known as the kelp’s holdfast.

Original research: http://dx.doi.org/10.1371/journal.pone.0229259

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Chestnut menace

Invading clonal

wasps. Chestnut menace spreading

yet no males required.

 

The Chestnut gall wasp arrived in Europe in 2006, imported accidentally from China. Since then it has begun to spread and devastate European Chestnut trees.

Bonal et al (2018) have now revealed that the European population has very low genetic diversity due to 1) the founding of the population by a small number of individuals, 2) an endosymbiont bacterial infection present within the population that is known to have male-killing tendencies and 3) it’s parthenogenetic reproduction strategy. This is where females are able to reproduce and produce female offspring without the need to be fertilised by males. No males have been observed in the European population and the females and their offspring are effectively clones of one another.

Original research: https://doi.org/10.1038/s41598-018-23754-z

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Declining monarchs

Declining monarchs:

Habitat not climate is

your Achilles’ heel.

 

Understanding why a species is declining is a large part of establishing a suitable conservation approach. In North America the monarch butterfly population has sharply declined in recent decades, yet the reasons for this were unclear until now.

Thogmartin et al (2017) investigated monarch butterfly populations and found that the decline is largely down to habitat loss from herbicide use and the loss of overwinter forest, as well as insecticides. Whilst climate impacts on yearly population size, this is not enough to explain the decreases in monarch butterfly population recorded over recent decades.

Original Research : https://doi.org/10.1098/rsos.170760