This Valentine's weekend some American zoos are offering an adults-only opportunity to discover animals' amorous¹ antics, and perhaps pick up a few tips.

For 75 dollars per person, including champagne² and brunch³, a Philadelphia Zoo is providing a three-hour romantic tour, dubbed⁴ "Lovin' on the Wild Side."

Sadly -- although the tour is for over 21's only -- it is not guaranteed that every visitor will get lucky.

"We don't guarantee that the animals will have intimate moments when we see them," the zoo's Laura Warner cautioned.

But with a bit of luck, Warner said, guests might see an array of unusual overtures⁵.

Tortoises, Warner explained, "like to nibble⁶ their toes to get to know each other."

"Bats, since they sleep upside down, there are other things they do upside down," she added. "The giraffes like to rub each other's neck."

But the most unusual -- and brutal⁷ -- mating rite⁸ may come in the spiders' enclosure.

"After their intimate moment, the female often bites off the male's head," she said.

But for lessons in attentiveness⁹ and trust visitors need look no further than the rhinoceros¹⁰ hornbill.

According to Dean Noble, director of marketing¹¹ at Santa Barbara Zoo in California -- which is also offering tours -- this black-bodied bird is the master of post-coitus care.

"The male of the species seals the female in a hollow tree with mud and then feeds her through the hole and removes the excrement¹² until the chicks are ready to fly," he said.

美国一些动物园将在本周末情人节期间推出一项仅限成年人参加的“观光“活动，游客将有幸看到动物们表达爱情的举动，或许还能从中学到一些经验。

费城动物园推出了三小时的浪漫之旅，号称“狂野之爱”，票价为每人75美元，其中包括香槟酒和一份早午餐。

遗憾的是，尽管该活动仅限21岁以上的成年人参加，但不能确保每位游客都能一饱眼福。

费城动物园的劳拉•华纳提醒说：“我们不能保证游客在参观时动物一定会有亲密的举动。”

但所幸游客们能看到很多不同寻常的“爱情表白”。

华纳解释说，例如乌龟“喜欢通过咬脚趾来认识对方。”

她说：“蝙蝠在睡觉时一般倒挂着身体，所以它们在做其它事情时也采取同样的姿势。而长颈鹿则喜欢相互摩擦颈部来表达爱意。”

而最不同寻常和残忍的交配当属蜘蛛。

她说：“在交配后，雌蜘蛛通常会咬掉雄蜘蛛的头。”

如果游客们想学习情侣间应如何善待和信任对方，千万别错过马来犀鸟。

据同样将推出该活动的加州圣巴巴拉动物园的营销总监迪安•诺布尔介绍，这种黑色的鸟在交配后十分懂得照顾对方。

他说：“雄鸟会将雌鸟安置在一个树洞里，洞口封上泥巴，只留一个小孔供喂食使用，并帮它清除粪便，直到幼雏会飞为止。”