A birder who has built up a reputation in birding circles for identifying birds incorrectly, in particular with regard to claims of rarities. Twitchers think twice before chasing rarities that have been recorded by a suspected stringer. A stringer often has a large lifelist which is considered with scepticism by other birders. Difficult to prove that a person is a stringer, and thus birders are sometimes unfairly branded as such.
Stochastic (from the Greek στόχος for aim or guess) refers to systems whose behaviour is intrinsically non-deterministic, sporadic and categorically NOT intermittent. A stochastic process is one whose behaviour is non-deterministic, in that a system's subsequent state is determined both by the process's predictable actions and by a random element. However, according to M. Kac and E. Nelson, any kind of time development (be it deterministic or essentially probabilistic) which is analyzable in terms of probability deserves the name of stochastic process.
Spermatogenesis is the process by which male primary sperm cells undergo meiosis, and produce a number of cells termed spermatogonia, from which the primary spermatocytes are derived. Each primary spermatocyte divides into two secondary spermatocytes, and each secondary spermatocyte into two spermatids or young spermatozoa. These develop into mature spermatozoa, also known as sperm cells. Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa.
Spermatozoa are the mature male gametes in many sexually reproducing organisms. Thus, spermatogenesis is the male version of gametogenesis. In mammals it occurs in the male testes and epididymis in a stepwise fashion, and for humans takes approximately 64 days. Spermatogenesis is highly dependent upon optimal conditions for the process to occur correctly, and is essential for sexual reproduction. DNA methylation and histone modification have been implicated in the regulation of this process. It starts at puberty and usually continues uninterrupted until death, although a slight decrease can be discerned in the quantity of produced sperm with increase in age.
The spotted lion or Mazori is variously claimed by zoologists and cryptozoologists to be a distinct race of lion adapted for a montane rather than savanna-dwelling existence, a rare natural hybrid of a leopard and lion, or an adult lion that retained its childhood spots. It is believed to have been smaller than a lion but slightly larger in size than a leopard and lacking any distinguishable mane. It has been reported in the wild and the skin of a specimen exists, but it has yet to be confirmed as either a separate species or subspecies. Belgian cryptozoologist Dr Bernard Heuvelmans proposed the specific name Leo maculatus in 1955.
In biology, two species or populations are considered sympatric when they exist in the same geographic area and thus regularly encounter one another. An initially interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation. Such speciation may be a product of reproductive isolation — which prevents hybrid offspring from being viable or able to reproduce, thereby reducing gene flow — that results in genetic divergence. Sympatric speciation does not imply secondary contact, which is speciation or divergence in allopatry followed by range expansions leading to an area of sympatry. Sympatric species or taxa in secondary contact may or may not interbreed.
(Amerind term for plains) Savannas, such as the Serengeti in Africa, are grasslands. They may have a few sparsely distributed drought-resistant, fire-resistant or browse-resistant trees. Savannas are also referred to as llanos or cerrado.
(Faimly: Fringillidae) Siskins are seed-eating songbirds in the finch family. They are the size of goldfinches (about 8 centimeters).
A distinct kind of animal. Members of the same species can reproduce with each other.
forest in which some but not all tree species lose their leaves during one season of the year
also: sexual dichromism, sexually dichromatic males and females of the same species having different fur colorations and/or marking patterns
a more environmentally friendly type of farming which avoids clearing areas of trees for farming and instead grows crops under the canopy of trees, thereby maintaining a wildlife habitat for many arboreal species
the tissue surrounding the tail and genitals of female primates that swells with changes in hormones associated with estrus
also: sexually dimorphic males and females of the same species having different external characteristics and features
also: sneak copulation copulation by a male with a female in another male's territory or group
instinctive action, movement, posture, or behavior that does not need to be practiced or learned before it can be done correctly
a plug that a male leaves in a female's vagina after mating as a tactic in reproductive competition
Sexual Selection Theory
individuals are able to attract more mates by being more attractive to individuals of the opposite sex; this attractiveness is based on physical characteristics that may be also linked to social dominance or overall health
prominent point on top of the head where two skull bones meet
the systematic use of signals to refer to objects in the external world; using different signals to represent distinct objects in the environment
Scramble Competition Polygyny
polygyny in which males make no effort to defend individual exclusive mating territories, but instead attempt to outrace their competitors to receptive females