The flagship species on the Alentejo Plains, and its conservation, (due in large part to SPEA and the LPN), has been the salvation not only of large swathes of wonderful countryside but also of many species that would otherwise find it difficult to survive here. With approximately 2,000 resident individuals in Portugal, and arguably the heaviest flying bird in the world, Great Bustards are listed as Vulnerable by Birdlife International. With a global population just shy of 50,000 individuals, their available habitat is sadly becoming smaller and they are increasingly under threat, even though they have possibly the widest distribution of any threatened species, ranging from the western Atlantic seaboard eastwards all the way to the Pacific coast in China, the largest population density residing in the Iberian Peninsula.
A typical male weighs anywhere between 10 and 18 kilos, (with the heaviest verified record being an individual in Manchuria that tipped the scales at 21 kg, though there have been heavier unverified reports), while the female is much lighter at only 4 to 8 kg. Average life span is 10 years, (max recorded is 28), with females first breeding at around 3 and males at about 5. Chicks are mainly carnivorous for their first year and then switch to a herbivorous diet, though at all times of their life they are essentially omnivorous.
On average 80% of Great Bustards die in the first year of their life, with the greatest causes in Portugal, (apart from human pressure and habitat loss), being predation by foxes and raptors, notably Spanish Imperial Eagles. Apart from this, male mortality is high during their first year or two of breeding due to aggressive fighting during the breeding season. Their is a video of this in the pictures below.
The male's display at this period is known as the "Foam Bath Display"; they lower their head to the base of their neck, raise their whiskers, fluff out their tail, puff out their chest and turn their wings almost upside down. By doing this they become more or less a large white ball and extremely obvious to any passing female. This display typically takes place during the last week in March and the first two in April, though on occasion and depending upon the weather, this three week window can be stretched to six or even eight. The male's mating call is enough to get even the dourest person falling to the floor, but should not be played to Great Aunts.
At most times of the year Great Bustards can be found relatively easily if one knows where to look. They are usually in small droves comprising up to 30 birds, but occasionally they gather in large numbers and the most I've ever seen in one place at the same time was 200+. There is a long-range picture below of 120 or so below, taken in 2013. However their camouflage is particularly good and the only reason I was able to see this number on this day was the two pairs of Spanish Imperials that flew over at the same time and flushed the drove.
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