How many {species kept} are to/by {moose} ?
How many moose species are there?
How many species of moose exist?
SELECT ( COUNT ( ?t ) AS ?l ) { ?t property:species_kept resource:Alces_alces }
SELECT (COUNT(?sub) AS ?subs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?sub .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P1990> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q35517 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P1990 wd:Q35517 }
6