Arxiu d'etiquetes: habitat loss

Cetaceans have a negative response to summer maritime traffic in Westeran Mediterranean Sea

A team of researchers of several Italian organizations has published on May 2015 its findings about the responses of cetaceans in high sea waters to summer maritime traffic in the Western Mediterranean Sea. This post is a summary of this study. 

INTRODUCTION

Nowadays, cetaceans have to face several threats, like the loss of their habitat, depletion of resources, interaction with fisheries and chemical and acoustic pollution, among others. In the case of ship transport, it can cause long-term changes in distribution, short-term changes in behaviour or direct physical injuries (e. g. collisions).

The Mediterranean Sea is one of the world’s busiest waterways. Moreover, shipping traffic is growing together with the concern of its impacts on fauna. In addition, we have to have in consideration that summer month are the busiest in naval traffic, especially due to the increase on cruise ships and passenger ferries.

The goal of this study was to outcome if the intensity of traffic in high sea waters was statistically different between presence and absence of cetacean sightings.

STUDY AREA AND DATA COLLECTION

Because of most of the Mediterranean cetaceans are mainly pelagic and there is a lack of information in these areas, the research had been conducted along six transects within shipping routes that connects Italy, France and Spain in high sea waters (placed in Ligurian-Provençal basin, the northern and central Tyrrhenian Sea and the Sardinian and Balearic Seas).

Mediterranean Sea basin (Picture from Encylopaedia Britannica)
Mediterranean Sea basin (Picture from Encylopaedia Britannica)

The transects were surveyed from June to September between 2009 and 2013 using ferries as observation platforms. During this period, more than 95,000 km were surveyed and the presence of eight cetacean species was recorded.

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CETACEANS AND MARITIME TRAFFIC

In locations with cetacean sightings, the number of vessels was 20% lower than the number of vessels in the absence of sightings. In the case of the three most frequently sighted species; fin whale (Balaenoptera physalus), striped dolphin (Stenella coeruleoalba) and sperm whale (Physeter macrocephalus); this difference was, respectively, 18%, 20% and 2%. Concerning other species, in the case of Cuvier’s beaked whale (Ziphius cavirostris) the difference was 29% and in the Risso’s dolphin (Grampus griseus) was 43%. It was found that for bottlenose dolphins (Tursiops truncatus) the difference was insignificant. Finally, for common dolphin (Delphinus delphis) and for pilot whale (Globicephala melas) any conclusion can be given.

Nevertheless, despite the number of ships recorded during cetacean sightings was lower in all areas, the percentage difference range from 11 to 49% among areas.

So, in high sea areas during summer, where cetaceans were seen, there were a significantly lower abundance of ships. Some explanations can be given: animals could tend to avoid more impacted zones with small displacements by seeking areas with fewer vessels, could change their distribution to occupy low traffic areas or could increase diving activity where intense traffic occurs. The intensity of the response of cetaceans to the intensity of traffic has important differences among areas and species. So, there are several factors that affects this percentage difference, like specific ecological needs and local environmental conditions. 

In the case of fin whale, where marine traffic is intense, the presence of fin whales is generally lower, with the exception occurring in the central part of the Ligurian Sea. The explanation could be that this region is ecologically favourable in summer since it is a feeding ground for this species and these whales are present for feeding reasons. Therefore, there is a coexistence between traffic and fin whales.

Fin whale (Balaenoptera physalus) (Picture from Circe)
Fin whale (Balaenoptera physalus) (Picture from Circe)

Another example is striped dolphin. Due to its high mobility, this dolphin can avoid the presence of vessels and this could be the reason why there is a negative response between this species and ship presence.

Striped dolphin (Stenella coeruleoalba) (Picture from Marc Arenas Camps)
Striped dolphin (Stenella coeruleoalba) (Picture from Marc Arenas Camps)

About sperm whale and Cuvier’s beaked whale, there were no difference in both species in the Ligurian Sea and the reason probably is that sperm and Cuvier’s beaked whale have their feeding grounds in this basin and, moreover, the slopes and submarine canyons are confined in specific areas. However, differences are observed in other areas.

Sperm whale (Physeter macrocephalus) (Picture from Gabriel Barathieu).
Sperm whale (Physeter macrocephalus) (Picture: Gabriel Barathieu, Creative Commons).

Cuvier's beaked whale (Ziphius cavirostris) (Picture: Todd Pusser, Arkive).
Cuvier’s beaked whale (Ziphius cavirostris) (Picture: Todd Pusser, Arkive).

Finally, bottlenose dolphin did not show any response to traffic. Probably, because it is a coastal species, it is more used to sharing its typical habitat with maritime traffic.

Bottlenose dolphin (Tursiops truncatus) (Picture: Brandon Cole).
Bottlenose dolphin (Tursiops truncatus) (Picture: Brandon Cole).

REFERENCES

This post has been based on this paper:

  • Campana, I; Crosti, R; Angeletti, D; Carosso, L, David, L; Di-Méglio, N; Moulins, A; Rosso, M; Tepsich, P & Arcangeli, A (2015). Cetacean response to summer maritime traffic in the Western Mediterranean Sea. Marine Environmental Research, 109, 1-8

Difusió-anglès

Bearded vulture: conservation of a unique bird

Last month a bearded vulture was born for the first time in Spain of parents bred in captivity and reintroduced into the wild. The bearded vulture is the only bird in the world that feeds almost exclusively on bones. Like the Iberian lynx, it is one of the emblematic animals of the Iberian Peninsula and it is endangered, so it is subject to various conservation and reintroduction programs. In this article, we encourage you to find out more about the bearded vulture and the spanish conservation projects.

DESCRIPTION

The bearded vulture (Gypaetus barbatus) is a diurnal bird of prey popularly included in what is called vultures, scavenger and ghoul birds (they feed on dead animals). However, the bearded vulture is quite different from other vultures:

Quebrantahuesos (Gypaetus barbatus) adulto. )Foto de Jose Luis Ojeda)
Adult bearded vulture (Gypaetus barbatus). (Photo by Jose Luis Ojeda)

 

  • It is so highly specialized that 85% of their diet are bones (osteophague) of dead mammals such as wild ungulates (chamois) and domestic cattle (goats, sheep). It can swallow bones up to 25 cm, and if they are too large catches them, rises them to 20-40 m and crashes bones against the rocks into smaller pieces that can swallowIt also uses the same technique to break tortoise shells.
  • It is very large, with a wingspan up to 2.8 meters and a weitgh up to 7 kg.
  • In general it isn’t noisy: it just whistles if it is excited or during the mating season.
  • It hasn’t the typical plucked vulture head. Vultures have a few or no feathers on their heads to maintain an optimum hygiene after putting their head in dead animals. Due to its peculiar diet, the bearded vulture has more feathers on head and neck, with its characteristic beard” below the peak.
  • The plumage is the same for both sexes but changes with age. The typical reddish and yellowish adults plumage is due to their habit of bathing in mud rich in iron oxides, otherwise they will had a white breast.

Fases del plomatge del trencalòs, segons Adam i Llopis (2003). (Imatge de © X. Parellada.)
Plumage phases of the bearded vulture, Adam and Llopis (2003). (Image by © X. Parellada.)

In this video (5 minutes, catalan) you can see bearded vultures in flight, breaking bones, engulfing them, raising a chick in the nest and bathing in mud.

REPRODUCTION

Bearded vultures nests on ledges and natural rock caves in the mountainous and rugged areas where they live. They have stable partner for life from age 7 and the reproductive cycle has different stages:

  • Pre-laying (September to November): nest building (covering it with branches, wool, feathers, bones ), defense of territory and sexual activity.
  • Incubation (December-February): they lay one or two eggs with a time difference of 6 days. Both sexes participate in the incubation for 53 days.
  • Nurturing (March-August): the largest chick kills his brother (fraticidal violence) to ensure survival. Parents provide food and when the chick leaves the nest (June-July), learn from them to find and prepare food until their emancipation.
  • Emancipation (January): displacement (thousands of kilometers) and dating back to the land where it was born to breed (philopatric instinct).

Seguimiento de nidos naturales mediante cámaras. (Foto: FCQ)
Tracking of natural nests with cameras. (Photo: Foundation for the Conservation of the Bearded Vulture)

DISTRIBUTION

Subspecies Gypaetus barbatus meridonalis is distributed by the South and East Africa, while Gypaetus barbatus barbatus by North Africa and parts of Eurasia (see map).

In the Iberian Peninsula is found naturally only in the Pyrenees (Catalonia, Aragon and Navarra). Spain is the European country with more breeding couples registered (about 130, 2014 data).

gypaetus barbatus, quebrantahuesos, trencalòs, berded vulture distribution, distribución
Bearded vulture distribution. In red, areas in which has been reintroduced . (Image by Mario, Wikimedia).

THREATS

Bearded vulture populations are declining. It is ranked globally asnear threatened” in the IUCN Red List and “endangered” in the Spanish Catalogue of Endangered Species. Current threats they face are:

  • Death by poisoning (illegal baits, poisoned animal consumption, consumption of remains of lead hunting ammunition plumbism).
  • Death by electrocution or collisions with power lines and wind turbines of wind farms.
  • Poaching
  • Habitat loss and decreasing of reproductive efficiency because of the humanization of the medium (urbanisation, adventure sports )
  • Reduction of food (cattle in stables, obligation to bury the corpses )

Quebrantahuesos muerto por envenenamiento. (Foto: DARPAMN)
Bearded vulture dead by poisoning. (Photo: DARPAMN)

CONSERVATION IN SPAIN

Due to the limited distribution of populations, their low number and difficulty to colonize new territories, in 2014 thirteen autonomous communities signed a protocol for the recovery of vultures in Spain. The most prominent action of this protocol is to strengthen the National Strategy for the Conservation of the Bearded Vulture in Spain (started in 2000) and the Programme Captive Breeding (2001), with actions such as the revaluation of rural areas, supplementary feeding and support for traditional farming practices. This strategy also involves the reintroduction in historic areas where the bearded vulture has been extinguished:

WHAT IS HACKING?

Hacking or rural upbringing is a technique that involves the release of captive-bred animals in an area that the bird assimilates as its birthplace. If successful, the bearded vulture returns to settle and breed. This technique did not has a conservationist origin, since it was developed by falconers in the Medieval Age. Falconry (hunting with birds of prey) are also currently used for wildlife control at airports or cities.

In falconry hacking consists in lefting in an elevated cage chicks that can feed by themselves. Falconer feeds them without being seen. After a few days they open the cage, using it as a basis for learning to fly. They are still feeding them until they learn to hunt by themselves and leave the cage. The young ones connect the cage as its birthplace so it will always return.

Alimentación de un pollo con un señuelo para evitar el contacto humano. Foto: Fundación para la Conservación del Quebrantahuesos
Feeding a chick with a decoy to avoid human contact and make its life possible in the wild. (Photo: Foundation for the Conservation of the Bearded Vulture)

The center managed by the Gypaetus Foundation is based on the natural breeding, with minimal human intervention. Parents raise and feed their young from the second week of hatching. To monitor the nests a video surveillance system is used.

Since 2006, 31 bearded vultures have been released from captive breeding and each one is tracked by GPS transmitters. Currently 15 individuals are still sending signals (9 were killed and 7 stopped working). As said in the introduction, the good news is that last month was born the first chick result of released individuals (Tono and Blimunda) by hacking technique.

For more information, check out this documentary (in spanish) about the bearded vulture and its conservation (El bosque protector. Fauna amenazada, El Quebrantahuesos, 29 minutes).

REFERENCES

MIREIA QUEROL ALL YOU NEED IS BIOLOGY